Category: Transportation

Anything related to transportation, including cars, traffic, other modes of transport, and so on.

Post #1932: The death of my electric vehicle has been greatly exaggerated.

 

I bought a 2020 Chevy Bolt about two weeks back. It’s an electric vehicle with a roughly 250-mile range.  I did my research. Waited for prices to drop.  Got a pretty good deal on a low-mileage car. I think.  Post #1924 summarizes that.

Post #1924: I bought a Chevy Bolt.

And wouldn’t you know it, the very next week the news was full of horror stories about what a bad idea EVs are, owing to poor performance in the cold.  Long lines at public chargers, people being stranded, people getting towed.  The whole nine yards.  This, accompanied by the usual sneering comments from John Q Public.

OMG, did I just make a huge mistake? Continue reading Post #1932: The death of my electric vehicle has been greatly exaggerated.

Post #1926: A Prius driver takes a pass on Chevy Bolt “one-pedal driving”.

 

Do electric vehicles (EVs) get rear-ended more often than conventional cars do?

They certainly should.

That’s my conclusion after trying out the “one-pedal driving” mode on my new (used) 2020 Chevy Bolt.   And working through the logical consequences of it.

The practical bottom line of this post is that you should think twice before you tailgate an EV in traffic.  Because the chances are good that they can stop a whole lot faster than you can.   And may give you less warning when they do.

Not convinced?  Keep reading the parts in red, below.

Words do not do it justice: An accurate description of one-pedal driving mode.

Source:  Yeah, I know it’s a front-wheel-drive car.  The Gencraft AI doesn’t, though.  Almost all pictures here are courtesy of Gencraft.

Here’s your typical bland one-sentence description of one-pedal driving mode:  “With one-pedal driving, the car has enhanced regenerative braking, and will begin to slow as soon as you ease up on the gas (accelerator).”

Before I bought a Bolt, my reaction to that was, big deal.  Almost all modern cars do that, to a degree.  Anything with an automatic transmission slows when you take your foot off the gas.  All hybrids use regenerative braking, that is, they slow down by generating and storing electricity, reserving the friction brakes (pads pressing on rotors) as a last resort.

Some EVs can now do it more?  Whoop-te-doo.

Now that I own a Bolt, I know that description is missing a key word:  Abruptly.  Or, rapidly. Or, with great force.  Take your pick.

Taking your foot off the gas in “one-pedal” mode is nothing like taking your foot off the gas in a normal or hybrid car.  You don’t coast, at all.  You stop, pronto.  Not quite a wheels-locked panic stop.  But far faster than I normally stop, and far faster than anyone would reasonably expect me to stop in traffic.  In the Bolt, in one-pedal model, take your foot off the accelerator and you pull a few tenths of a G worth of deceleration.  Enough to pull you forward in your seat.  Enough that there’s no way I would engage that mode in snowy or icy roads.  Enough that I’d think hard about it before I turned one-pedal driving on in a driving rain.

Enough, already.  You get the point.  Here’s a more accurate description of one-pedal driving mode:

The act of lifting up on the accelerator, in one-pedal driving mode, is equivalent to pushing the brake pedal.  Hard.  Your (lack of) accelerator pedal is your brake pedal.  It’s not 100% as much force as you can get, if you actually do mash down the brakes.  But it’s an appreciable fraction of it.

You may again think, so what?  So you can, in effect, actuate the brakes, without hitting the brake pedal.  What’s the big deal?

Keep reading.

Brake lights?  We don’t need no stinkin’ brake lights.

But wait, it gets better.

Prior to mid-2023, some EVs would do that — stop fairly abruptly, in one-pedal mode — without turning on the brake lights.  And no, I’m not kidding about that.  (Reference).

The worst of those were fixed via software update, so now, all EVs on U.S. roads will now show brake lights, at some point, during some level of deceleration, in one-pedal driving mode.

As an afterthought.  Does that make you feel better about it?

But even now, an EV manufacturer’s decision on when, exactly, to show brake lights, during rapid braking in one-pedal driving mode, is entirely voluntary, and entirely up to the manufacturer, here in the U.S.A.  And for all of them, those lights turn on after the car has started slowing down.

Oddly enough, if you see this brought up on-line, you’ll see nothing but apologists for it.  Ah, cars have always had ways of slowing down without showing brake lights.  Let off the gas, in an automatic-transmission car.  Downshift in a manual.  Or, if you’re a jerk, hit the parking brake to stop, to fake out the folks behind you.

But those events were either mild in nature (automatic transmission), or rare and mild (nobody in the U.S. drives a manual these days, and nobody in the last 50 years has been dumb enough to wear out their clutch rather than brake pads by routinely slowing the car by downshifting).  Or required outright malice, like using a hand brake to stop.

Now, by contrast, you’re putting out a whole fleet of cars, for Joe and Jane Driver, all of which are designed to be driven without touching the brakes.  Designed to allow for substantial rates of deceleration without using the actual brake pedal.  And for which the decision about whether, or when, to turn on the brake lights at some point during that one-pedal deceleration, is an option for the manufacturer to decide. 

Let me offer a clear contrast to what you are used to, in a traditional gas car.  There, the brake lights are designed to light the instant you rest your foot on the brake pedal.  Brake lights are actuated by a switch that typically sits directly above the metal bar holding the brake pedal.  That switch has a fine adjustment on it.  You literally fine-tune-it so that the tiniest movement of the brake pedal closes the switch.  Even the lightest possible braking pressure will turn on your brake lights.  Properly adjusted, you literally turn on the brake lights before the brake pads make contact with the rotors.

So we now have a mixed fleet of cars on the road.  For 99% of them, the brake lights illuminate as soon as the driver puts on the brakes.  For the remaining 1%, the lights may come on at some point, after the driver has “put on the brakes”, assuming the rate of deceleration exceeds the manufacturer-specified threshold.

Yeah, what could possibly go wrong with that?

Braking distance versus stopping distance.

Definitions:  Both terms apply to panic stops.  Braking distance is how far your car travels, from the moment that you’ve firmly stomped on the brakes, until you reach a complete stop.  Stopping distance, by contrast, is that, plus the distance you travel during your “reaction time”, that is, the time it takes to say “oh shit”, move your foot off the gas, and hit the brakes.

Honking the horn is optional, but highly recommended here in Northern Virginia.

Now for just a bit of math.

1:  It takes about three-quarters of a second to lift your foot off the gas, and put it on the brake, in a panic stop.  That’s in addition to the initial reaction time — the time it takes you to realize you need to stop quickly.  (Estimates vary, that’s my reading of the literature on the subject.)

2:  At 30 miles per hour, in that amount of time, a car moves about two car lengths.  (Calculated as (30 MPH *5280 FT/MI *(0.75/(60*60) HOURS) = ) 33 feet.

3:  EVs in one-pedal driving mode can initiate an abrupt stop without moving their foot to the brake pedal.

My takeaway from all that is that EVs in one-pedal driving mode should be able to panic-stop somewhere around a couple of car lengths shorter than traditional cars.  That’s not due to better brakes, or better drivers.  That occurs because they begin to brake rapidly before they even move their foot to the brake pedal.

Yeah, what could possibly go wrong with that?

Summary

Shorter stopping distance is just dandy if you’re driving an EV in one-pedal mode.  But maybe isn’t such a plus for the person in a standard vehicle, tailgating an EV in one-pedal mode.

If you are in traffic, behind an EV in one-pedal mode, and the EV in front of you makes a panic stop, you need to be aware that, compared to a conventional car or hybrid:

1: That EV is inherently capable of stopping faster.

2: That EV will give you less time to realize it is stopping.

And nothing about that car will give you the faintest hint that those two factors are in play.

You’ve been warned.

Background:  Regenerative braking the Toyota way, or why Bolt one-pedal mode does me more harm than good.

We changed the brake pads on my wife’s 2005 Toyota Prius sometime around 140,000 miles.  Up to that point, the brakes hadn’t needed any attention.

The crazy thing is, that’s not even brag-worthy.  Going 100K miles between brake jobs is normal for any car with regenerative braking.

The Prius has regenerative braking.  To the greatest extent possible, the car slows down by turning itself into an electric generator.  It converts the forward momentum of the car to electricity, which then charges the traction battery.  Cars with regenerative braking routinely go 100,000 miles between brake jobs.  So says the U.S. DOE.

No material efficiency gains — for me.

The reason for the low brake wear in a Prius is that almost all the braking energy is done electrically.  In an ideal gentle stop, the friction brakes only kick in below about 5 MPH.  (If your rotors have surface rust, and your windows are open, you can hear that happen until you knock the rust off the rotors.)

In an idealized stop from 30 MPH to zero, you can easily calculate the fraction of braking “power dissipation” accounted for by electrical generation versus friction brakes.  Kinetic energy goes as the square of the speed, so, in a hypothetical gentle stop from 30 MPH to 0 MPH, where the friction brakes only handle the part below 5 MPH, the fraction of braking energy is:

Friction fraction of braking energy = 5-squared/30-squared = 25/900 = ~3%

Electrical Fraction of braking energy = 1 – friction fraction = 97%.

In other words, with a reasonably gentle stop, in typical suburban traffic, regenerative braking (Toyota-style) converts about 97% of the car’s forward momentum to electricity.  You don’t get to keep all of that, because there are losses in the electric motor/generators, the wires and charging electronics, and in charging the battery.  Maybe you keep 80% of that, or so.

One rationale offered for EV one-pedal driving is that it improves efficiency by recapturing more of the potentially available energy from braking the car.  That’s because you can literally bring the car to a full stop, and so, in theory, capture 100% of the car’s forward momentum and convert it to electricity.  Of which, again, you might be able to keep and use maybe 80%, after all the relevant losses are factored in.

And that’s the main reason that Bolt one-pedal driving does more-or-less nothing for my driving efficiency.  Because, despite what you may read, the Bolt’s regenerative braking does more-or-less the exact same thing as the Prius, during moderate stops.  In normal (not one-pedal) driving, when I take my foot off the gas, the car begins to recapture energy through regeneration.  And when I push gently on the brake, it begins to capture even more energy through regeneration.  Just like a Prius.  (All you have to do is look at the dashboard, as you brake, to see that this is true.)  And in a normal, gentle stop, with rusty rotors, you can hear the Bolt friction brakes engage at about the same speed as the Prius — about 5 MPH.

I guess if you drive like a bat out of hell, regenerative braking can improve your efficiency somewhat.  Plausibly, those who routinely make quick stops can benefit from converting more of the stop to electricity, before the friction brakes kick in.

But my driving habits were formed during the Arab Oil Embargoes/energy crises of the 1970s.  And I’m cheap, to boot.  So I try to avoid rapid stops.

My gut reaction, from reading about this, is that the real fan-boys for one-pedal driving are, in fact, those who want to drive like a bat out of hell.  They like it for the “sporty” feel, and how it lets them zip around all that much faster.  Which, to me, makes the whole “efficiency” argument kind of silly.  If you drive that way, clearly efficiency isn’t your goal.  You’d get more miles per KWH by not trying to drive the Bolt like a sports car.

So, from my perspective, as far as efficiency goes, one-pedal driving provides a marginal improvement in efficiency, for those with habitually inefficient driving styles.  Turning that around, if you’re a laid-back driver by nature, you ain’t going to get much additional efficiency out of one-pedal driving, beyond what you get from regenerative braking in “normal” driving mode.

Extras for experts, 1:  There is one weird final twist on this, in that, in a hybrid, regenerative braking doesn’t much matter.  It might typically add just 2% to the vehicle’s overall efficiency.  That’s from a combination of factors.  First, even with the efficient Atkinson-cycle engine of a Prius, you start off by wasting 60% of the energy in the gasoline.  Second, with relatively small electric motor/generators, and most importantly a relatively small battery, the amount of regenerative braking force — the amount of current you can safely generate and squeeze into the battery, without damaging anything — is highly limited.   So for the U.S. EPA drive cycle, with its extended periods of fast stop-and-go driving, you tend to show only a modest amount of energy recapture, as a fraction of the total energy used by the vehicle.

In an EV, by contrast, regenerative braking is a much higher contributor to overall vehicle efficiency, as the Federal government measures it.  First, unlike a hybrid, all the inefficiency in converting fossil fuels to electricity is “off the books”, so to speak.  That occurs at your local utility, not in your car.  The calculation of overall car efficiency starts with charging it, so as a whole the vehicle appears to have vastly less total wasted energy, than a hybrid does.  Second, with large motors and much larger battery, you can safely put more current into the battery.  Thus, in a hard stop, an EV can likely capture more of the energy than an hybrid can, prior to applying the friction brakes.

Old dog, new trick — look ma, no brakes!

The first thing about Toyota-style regenerative braking is that it’s absolutely seamless.  In the best case, you wouldn’t even guess that the car had this feature.  Only if you listen very closely, and brake very slowly, can you discern the point at which the friction brakes are engaged.

The second thing about Toyota-style regenerative braking is that hybrids with regenerative braking behave exactly the same as any non-hybrid car with automatic transmission.  Take your foot off the gas, and the car begins to slow just a little bit, just like any other automatic-transmission car (then) on the road.  The harder you push on the brake pedal, the more braking force you get.

Regeneration in the Bolt, by contrast, feels nothing like a normal car in this regard.  It is far more aggressive, even in normal (not one-pedal) mode.  Take your foot off the gas in a Bolt, and you slow much faster than you would in a standard car with automatic transmission, or in a typical hybrid.  I have already had to break myself of the long-learned habit of lifting my foot from the gas when I see a red light ahead.  On the roads around here, If I were to do that in a Bolt, I’d come to a dead stop long before I make it to the light.

But I can live with that.  I lift my foot, eyeball the dash, and look for the something close to zero KW going into or out the battery.  It’s hardly a life-changing difference in driving technique.  Not after I had to re-learn driving for the Prius Prime, and its preference for constant-power (instead of constant-force) acceleration (Post #1618:  There ain’t no disputin’ Sir Isaac Newton).

But switching to one-pedal driving has one potentially life-changing difference:  You may lose the instinct to put your foot on the brake.  If you never need to panic stop, you can literally drive the car in one-pedal mode and never touch the brake.   (Some one-pedal fans brag about doing exactly that.)

So do I, as a 65-year-old guy, now want to train myself to drive in one-pedal mode?  This, when the approach to driving is so different from our other car (a Prius).  And this, where driving in this new style means basically to ignore the brake pedal.

Short answer, no.  Sooner or later, in NoVA traffic, I’m going to have to do a panic stop.  And when that happens, that panic stop happens on instinct.  It took me close to 20 years to get used to ABS, and to lose the instinct to release the brakes in response to a skid, and just keep my foot mashed to the floor.  I really, really don’t want to lose the instinct that tells me to hit the brakes in an emergency-stop situation.

So, it’s not that I couldn’t learn this new trick.  It’s that I probably shouldn’t.  Not with driving two different cars.  And not with my recent entry into geezerhood.  Better to leave sleeping dogs lie.

The Prius Gene

This is a true story.  We bought our first Prius in 2005.  The same week that we bought ours, hundreds of miles away, with no communication between us, one of my brothers also bought his first Prius.

We’re now a two-Prius family.  I think my brother and his wife have been a three-Prius family, with one going off to Prius heaven as a result of a freak highway accident.

My brother says the exact same thing about his Prius, as I say about ours:  It pushes all my buttons, in just the right way.  From the super-smooth acceleration with no gear shifts, to the dashboard feedback on mileage, pretty much everything about the car says “relax, chill, enjoy the drive”.

Maybe we both like that because that’s pretty much the way my dad drove.  Maybe we inherited the genes that give us that bent.  In any case, it seems to run in the family.

It takes some work to drive a Bolt as if you were puttering along in a Prius.  But for whatever reason, by golly, that’s how I choose to drive it.

So, no one-pedal mode for me.  It’s insufficiently Prius-like.

Post #1925: Bolt EV, party like it’s 1999.

 

The last car that I bought, before buying a used Bolt a) had a manual transmission, b) had a CD player, c) had no USB ports, not even for charging, and d) could only communicate with the outside world via the OBD-II port, as God and the U.S. EPA intended.

And, needless to say, ran on gasoline.

Continue reading Post #1925: Bolt EV, party like it’s 1999.

Post #1924: I bought a Chevy Bolt.

This morning I bought a three-year-old used car with just over 5,000 miles on the odometer.

Net cost, all in, just under $15K.  That’s ~$19K, out the door, at the dealer (including taxes, tags, and fees).  Less a $4K Federal tax credit.  For which I am depending on the dealer to file the critical paperwork with the IRS.

That’s a pretty good deal for any used car, these days.

The fact that it runs on electricity is a bonus.

The only thing missing is new car smell.  And for that, if I really want it, I can just buy some.

Note:  On that tax credit, you have to have sufficiently low income ($150K for married filing jointly).  Not every used EV qualifies.   Not every sale qualifies. Read the details before you even think of factoring that into your purchase decision. 

Continue reading Post #1924: I bought a Chevy Bolt.

Post #1922: Venn Diagram of Used Chevrolet Bolt Search.

A:   Not a salt-belt car.  Turns out, the majority of used Bolts for sale here in the DC area were sold new in the Northern U.S.  The cold isn’t the issue.  Multiple winters of driving on heavily-salted roads is the issue.  I don’t want a salt-belt car.

B:  No accidents, no obvious damage, no ludicrously excessive mileage.  I think the rationale there goes without saying.

C:  Dealer is not obviously a shithead.  And here, I’m not talking about the comments on Yelp (because those are always negative).  I’m just looking for a dealer where the majority of comments, on some mainstream site (e.g., cars.com), do not start off with some variation on “If I could give them negative stars … “.

As I sift through what’s listed within 25 miles of me, on Edmunds.com, this is how it shakes out.  This is what mathematicians call an over-determined system of equations.  Nothing satisfies all the constraints.  Or, the intersection of the areas is a null set.  Say it any way you like.

If I continue to pursue this, something’s going to have to give. At this point, I’m leaning toward buying a salt-belt refugee, from a seemingly decent dealer.  I mean, seriously, how much damage could three winters on salted roads cause?  Guess I may find out.

To be continued.

For the literal-minded of you, no, that’s not a proper Venn diagram of the situation. Some circles should overlap others, somewhere.  But it doesn’t look like a surprised face then, does it?  With the choice between literal mathematical correctness on a throw-away diagram, and some possible humor value, I went with attempted humor.  So sue me.  This is really more an expression of frustration over what ought to be a straightforward search for a commodity product.  But isn’t.

Post #1919: Salted Leafs and Bolts, an unexpected twist in my search for a used EV.

 

I’m in the process of narrowing down the used EVs I want to look at.

I just got a rude, but entirely logical, surprise.  It turns out that a lot of the late-model used EVs for sale in this area are salt-belt refugees.  That is, they were sold new in northern states, where they salt the roads heavily all winter long.  But were shipped south for re-sale as used vehicles.

The story.

Based on the ratings of car dealers on-line, I’ve focused on a couple of independent used car dealers in my area.  (FWIW, Kingstowne and Eastern’s Sterling).  I think maybe the phrase in italics is key, because these aren’t new-car dealers accepting trade-ins.  These are used-car dealers.

As I was doing my on-line due diligence, seeing what I can see about these cars by VIN, I happened to notice that one car I’m interested in — a 2021 low-mileage Bolt — was originally sold in Michigan.

Hmm.  Funny that this car ended up in Virginia.  But people move, and so on.  And yet …

I tracked down the original state of sale for the other two I’m focused on — 2020 and later, relatively low mileage.  Those were originally sold in Upstate New York, and Vermont.

One salt-belt car might be by chance.  But every car I’m looking at?  Highly unlikely that’s a coincidence.

I can guess what’s driving this.

EVs lose a lot of range in cold weather.  That’s a fact.  None of these cars has an efficient (heat-pump) heating system.   Also a fact.

I have to guess that:

  1. You have a lot more dissatisfied owners in cold-climate states.
  2. You get a much better resale price on these vehicles, in warm-climate states.
  3. So there’s a steady trade in shipping used EVs south for resale.

The issue isn’t that these were driven in the cold.  The battery management systems on these cars will all prevent the owners from damaging the batteries permanently by (e.g.) charging when the batteries are below 32F.

The issue is that all of these cars are salt-belt refugees.  That is, they were driven in the states where roads are heavily salted, for a significant fraction of the year.

After a few months of watching YouTube auto mechanics in salt-belt states (Watch Wes Work, from Illinois, and South Main Auto Channel, from upstate New York), one thing that comes through loud and clear is that salt is incredibly destructive.  Among the things I learned from those videos is the term “rust jacking”, which is when the accumulation of rust literally bends and breaks metal parts of the car.  Never seen that around here, and I’ve owned a lot of crappy old cars.

And so, once again, I need to stop and cool my jets, as I give this a re-think.  And look at what’s available as a used vehicle, from local new-car dealers.

Post #1918: Falling Leafs, fallen Bolts: The trend in used EV prices in my area.

 

I don’t drive much.  I haven’t had a car for a couple of years now, and have gotten along  by borrowing my wife’s car, when convenient.

I’d like to get my hands on a nice, used EV.   That’s a good choice, given that I’m going to use this for a grocery-getter and little else.

Depending on the price, of course.  And I’m clearly in no hurry to buy one.

Back in July I looked at my local market for used EVs and narrowed my best option down to a 2018 or later Nissan Leaf.  That’s laid out in a series of posts around Post #1837, and the posts just prior to that.  The year cutoff was due to a change in the Leaf battery chemistry that year, to a much more stable (long-lived) battery.

I have been checking back occasionally ever since.

And I’ve been reading articles suggesting a steep decline in the price of used EVs.  I see talk about price declines on order of 30% per year.   This is almost always attributed to the fact that most used EVs are Teslas, and Tesla made some steep price cuts to their models this past year.

In other words, a falling tide sinks all boats.  Those Tesla price cuts are rippling through the entire used EV market.

But in addition, Chevy cut the price on the Bolt last year.  Both to spur sales, and maybe because the Bolt was plagued by a significant recall due to battery fire issues in a handful of vehicles.  Chevy claims that’s taken care of, but they ended up replacing the batteries in tens of thousands of cars.

In any case, when I went back to re-assess my local market for used EVs, it sure did seem like prices were down.  So I did my best apples-to-apples comparison between what I looked at back in August, and now.  As shown above.

By my estimate, asking prices for a used late-model Nissan Leaf fell 14% in the last five months of 2023.  Or … on-order-of a 30%/year rate of decline. 

More interestingly, I can now get a used Chevy Bolt for about the same price as a used Nissan Leaf.  This is a change from the prior analysis, where my back-of-the-envelope on a Bolt of this vintage, five months ago, put the average asking price at $21,000.

But now, consistent with the decline in the Leaf price, there’s been an even steeper decline in the Bolt price.

Objectively, the Bolt looks like a lot more utility for the money.

  • The Bolt has about 90 more miles of range than the leaf (about 250, versus about 160 for the base Leaf)
  • It uses a standard (J1772) plug, instead of the soon-to-be-obsolete CHADMO plug on the Leaf.
  • It has active battery temperature management, compared to the Leaf’s passively air-cooled battery.

The sole drawback from my perspective is that the Bolt looks like a tiny little car, where the Leaf does not.  To me.  They have roughly the same interior volume, and the Bolt actually has a higher curb weight than the base Leaf.  But the Bolt is shorter by about a foot-and-a-half.  Just enough that I notice how small it is, compared to (say) the 2021 Prius that my wife drives.

For either car, if you had little enough income in the year of purchase, Uncle Sugar will give you a $4K tax rebate for purchasing that used US-made EV.  (Yep, for purchasing a used US-made EV.  Part of the Biden Administration’s buy-American industrial policy intersecting with its global warming initiatives. So, thanks, Joe Biden. I guess.)

Rumor has it that the big drop in the Bolt price is due to Chevy rehabbing and re-selling a lot of those recalled vehicles.  I’m not sure how much that is true.  What I am sure is that the Bolt looks like a pretty good option, if you trust Chevy to have fixed that rare battery issue.  If you pick and choose, you can plausibly pick up a three- or four-year-old car, with about 10K miles on it, for a net $13K or so.

This, where the only expensive component — the battery — comes with a mandatory eight-year/100,000 mile manufacturer’s warranty. Which should, in theory, take a whole lot of the risk out of this used-car transaction.  Roughly speaking, you pretty much have to get at least five years of driving out of the car, or the manufacturer (not the seller!) has to replace your battery.

As used cars go, that seems like a pretty decent deal, regardless of the fuel source.  The fact that this is the low-carbon alternative is almost gravy, at this point.   To me, based on what I’ve been looking at, this now looks like it’s just a pretty good deal on a used car.  Period.

I have to confess that the first and last Chevrolet product that I ever bought was a Chevy Vega.  It was a traumatizing experience in many regards, as those of you familiar with the history of the Chevy Vega will understand.

I guess, going on 40 years later, maybe I can find it in my heart to forgive, and give Chevy another try.

Post #1914: Pneumatic tires for wheelchair use, no good solution to the problem of flat tires.

 

This is a brief followup to the just prior post, on the use of non-pneumatic (e.g., solid rubber) tires on wheelchairs.

I’m trying to work out what I should recommend if asked to replace more wheelchair tires.  Traditional tires with air-filled inner tubes are much easier from the standpoint of the installer.  The question is dealing with the drawbacks of those from the wheelchair user’s perspective.

The only way to guarantee that a wheelchair tire won’t go flat is to use a non-pneumatic tire.  That includes solid rubber tires, and solid rubber inserts taking the place of an inner tube inside regular tires.

What I discovered in this post is that many anti-flat products available for bicyclists will not work for most wheelchairs, owing to the wheelchair’s use of narrow, high-pressure tires.

When all is said and done, between the past post and this post, I think I now have a fairly firm set of recommendations.

If you cannot tolerate a flat tire on-the-go, then opt for solid rubber tires (and not solid inserts in regular bike tires).  But mount them using the $35 steel bolt-to-the-workbench device sold specifically for mounting such tires on wheelchair rims.  Mounting them with simple hand tools is just too hard and too iffy.

If you can tolerate the occasional flat, the best option seems to be puncture-resistant tires and tubes.  All the rest of the anti-flat products available for bicycle use — chemical sealants, anti-puncture tire liners, tire “wipers, and the like — either won’t work with typical wheelchair tires, or are not available off-the-shelf in the right size or configuration for that use.

Background

Solid rubber tires and solid rubber tire inserts definitely will not go flat.  There’s no air in them in the first place.

But those tires have some drawbacks.  Per the just-prior post, both of those non-pneumatic options are difficult to install using ordinary hand tools.  In addition, solid inserts are difficult to purchase as they must match the tire fairly exactly.

Both types of non-pneumatic tires offer a harsher ride and higher rolling resistance than high-pressure pneumatic (air-filled) tires.  And there are relatively few options available in the correct size for typical wheelchair rims.

By contrast, traditional pneumatic bike tires (tire plus inner tube) are easier to purchase and install, but they have two big drawbacks.  They require frequent, routine re-inflation to maintain the correct pressure.  Otherwise they go soft, and that raises rolling resistance.  And they can go flat, unexpectedly, while you are out-and-about.

The latter is not just a problem for the high rolling resistance you get with a flat.  It’s all too easy to roll a flat bike tire right off the rim, or to damage both the rim and the tire if you keep going on a flat tire.

This post is my research into minimizing the hassle from both of those drawbacks:  routine periodic inflation, and flat tires.

Caveat 1:  In the particular case I’m looking at, my options are  24″ x 1″ or 24″ x 1-3/8″ tires.  This puts a lot of limits on the types of bike-tire solutions that can be adopted for wheelchair use.  You might have other options available if your rims can accept wider tires.

Caveat 2:  My only qualification for writing about this topic is that I’ve changed a lot of bike tires in my life.  And I happen to be friends with someone who uses a manual wheelchair.

Routine inflation:  An electric air pump can solve this problem.

Source:  https://www.homedepot.com/p/Husky-120-Volt-Inflator-H120N/325096203

Best guess, $20 and a trip to Home Depot gives an adequate way to maintain tire air pressure up to 100 PSI.

I don’t think it’s worth belaboring this.  All pneumatic bike tires lose air over time.  It’s not a leak, per se.  It’s that air diffuses through the rubber.  (The same thing happens to rubber balloons and car tires, just much faster and much slower, respectively).  The higher the tire pressure, and the thinner the tire/inner tube, the faster the tire goes soft.  There’s no way to stop it that I have ever heard of.

This means that pneumatic tires have to be topped up on a routine basis.  And in the modern world, the obvious solution for routine tire inflation is an electric air pump.

A standard full-sized manual bike tire pump doesn’t do the average wheelchair user much good for routine use.  Not only are they designed to be used while standing up, they are designed to be fast, that is, to move a lot of air with each stroke.  They do that by using a piston with a relatively large surface area.  But wheelchair users often prefer high-pressure (e.g., 140 PSI) tires, for the low rolling resistance such tires provide.  Even if a full-sized manual pump can achieve pressures like that, it takes a lot of force, owing to the large piston area.

The typical manual mini-bike-pump — the kind you take with you on a bike ride — is both slow and awkward to use.  They are slow because they have tiny little pistons, suitable for pumping tires to high pressures using only your arm muscles.  And they are awkward because they either clamp directly to the valve stem, or have just a short attaching hose, either of which essentially dictates exactly where the pump must be held, relative to the tire.  In essence, those pumps are made for emergency on-the-road use.  You can use them for routine tire maintenance, but I sure don’t.   

Compressed C02 cartridge pumps are expensive for use in keeping tires routinely inflated.  The poorly-designed ones appear hard to use, based on Amazon comments.  But even for the well-designed ones, depending on the pump and the tire, you’d be spending $1.50 and tossing away a metal C02 cartridge every time you topped off your tires.  Plus, based on what I read, C02-filled tires deflate more rapidly than air-filled tires, owing to something-something-something about the ability of C02 to diffuse through butyl rubber.  You’d turn your routine tire maintenance into a $100-a-year habit, for no particular reason.

The efficient solution is an electric tire pump. 

These days, you have your choice of 120 volt plug-in, 12 volt plug in, and rechargeable battery-operated pumps.  You only have to check a few things:

  • How loud are they?
  • Can they do high pressures?
  • How awkward are they to use?
  • How long will they last in routine use?
  • Is the battery replaceable?

And, of course, how much do they cost?  Because, near as I can tell from reading Amazon comments, the cheaper pumps tend to fail several of the checks outlined above.

I have no specific recommendation to make, other than the Home Depot offering shown above.  All I can suggest is (e.g.) reading the comments on pumps offered on Amazon.  In particular, a lot of cheaper battery-operated pumps cannot produce high pressures despite what the Amazon listing might say.  When in doubt, get one that plugs into the wall.

Avoiding flats:  Nothing is bulletproof

If you absolutely, positively must not have a flat tire, the only real option is solid, non-pneumatic tires.  In this section, I’m shooting for two things:

  1. A tire and tube setup that minimizes the risk of catastrophic flats.
  2. A simple, no-maintenance pump that can be kept on the wheelchair for emergency use as needed.

The pump is easy.  Any C02-cartridge inflator that fits comfortably in the hand should be adequate, as would a standard bicycle mini-pump with the addition of an extension hose.  Either would be small enough to be stored long-term on the wheelchair itself.

But finding a combination to minimize the chance of a wheelchair flat is hard, owing in part to the small size and high pressure of the typical wheelchair pneumatic tire.  Puncture sealants (e.g., Slime (r)) do not appear to work at high pressure.  Puncture proof tire liners do not appear to be available in the narrow widths required for wheelchair tires.  The only options that work for typical wheelchair rims combine relatively expensive “puncture-resistant” tires with relatively expensive “thorn-resistant” inner tubes.  Even with that, neither of those is likely to stand up to an ill-placed tack, nail, or screw.

So the bottom line is that there is no good anti-flat solution for pneumatic wheelchair tires. The best you can hope for is that any puncture is small enough that you can inflate the tire, on the go, enough to get you someplace where you can swap out the wheel.

Tire and tube setup.

An important restriction is that the only tires that I know will fit the rims I’ve been working with are 24″ x 1″, and 24″ x 1-3/8″ tires, designed for use with inner tubes.  These are narrow by bicycle standards, and that limits choices quite a bit.

Puncture-resistant tire liner:  No off-the-shelf option in this size. 

Source:  Amazon.com

These are (typically) just a tough piece of flexible plastic, designed to turn aside (e.g.) thorns.  Note what the original Mr. Tuffy tire liners don’t say:  Nails, tacks, screws, staples, and similar.  Given that I’ve had nails go right through the tread of a steel-belted radial car tire, I’m pretty sure a piece of plastic isn’t going to stop them in a bike tire.

But it’s moot anyway.  Near as I can tell, all the ones made for bicycles are too large for 1-3/8″ tires, and are certainly too large for 1″ tires.  For the Mr. Tuffy brand, 24″ wheel sizing starts at 1.95″ and goes up from there.

At best, I could cut them down and use them.  But I’d have to sand down the edges to be sure that the tire liners themselves didn’t cut the tube.

Tire sealants:  Dubious in higher-pressure tires.

Slime (r) does not make ready-made self-sealing inner tubes sized for a 1-3/8 tire.  That said, the original Slime (r) sealant was sold in bottles, to be squeezed into a bike inner tube after removing the valve core.  So it’s easy enough to make self-sealing 1″ or 1-3/8″ tubes from standard tubes and a bottle of Slime (r).  By reputation, this will stop (or greatly slow) leaks from small punctures for about two years.  After which, I think you have to remove and replace the old tubes.

So that’s an option.  Based on what I read on the internet, Slime works, somewhat.  Won’t stop a rip or tear in the tire.  May not seal fully.  But gives you enough sealant to get home on a tire with a small puncture.

This seemingly-knowledgeable user provides a major caveat:

Tire pressures above 45 psi are less effective at sealing, and above 60 psi, don’t expect any effectiveness at all.

Oddly, Slime (r) itself does not mention this limitation.  But now that I Google Slime (r) and tire pressure, I see warnings in multiple locations that Slime (r) and similar sealants will not work well in high-pressure tube tires.  I’m not entirely sure how accurate that is, but until proven otherwise, that’s a caveat for tires in the 100 to 140 PSI range.

FWIW, a competing product in this segment — Flat Out — specifically says “fat tire bikes” (reference).  The implication there is that this sealant would not work in (e.g.) road bikes with high-pressure tires.

Beyond that, Slime has a reputation for sometimes causing problems such as blocked valve stems.  All things considered, Slime (r) may be reasonable for low-pressure (“fat”) bike tires, but whether or not it will work well and without issues for thin, high-pressure wheelchair tires is an open question.

A final issue is the use of Slime (r) in mounted tires that might be stored, unused, for a considerable length of time.  Rumor has it that Slime (r) can “pile up” in the low section of the tire.  If you’re getting close to the point where the Slime loses its ability to flow, you may end up picking up a replacement wheelchair tire only to find that the low section of the tire (as stored) is now solidified Slime.

Puncture-resistant tire:  Expensive and somewhat effective.

As with tire liners, these aren’t a bulletproof solution.  It’s puncture-resistant, not puncture proof.  Near as I can tell, the only puncture-resistant tire marketed in the 24″ x 1-3/8″ size in the U.S. is marketed as a wheelchair tire.  Hence it costs two or three times as much as a regular tire.

Puncture-resistant tube:  Expensive, effectiveness unknown.

There are a handful of “thorn-resistant” (that is, extra-thick) inner tubes marketed in the 24″ x 1-3/8″ size.  These appear to cost about two to four times as much as a regular inner tube.  As with puncture-resistant tires, these are unlikely to stop a tack, nail, or screw.  Whether they provide any additional resistance to punctures from man-made objects, I don’t know.

Run flat tire:  No option in this size.

There are now foam inserts for bike tires that provide some degree of run-flat capability.  These are oriented toward tubeless tires typically used by (e.g.) bike racers.  Near as I can tell, there is no run-flat tire option available for something as small as 24″ x 1-3/8.

Tire wipers:  Maybe, but requires D-I-Y mounting.

A final offering for minimizing punctures goes by various names, but probably “tire wipers” is sufficiently descriptive.  These are typically wires that ride lightly on the tire, and knock off any solid debris that has stuck to the tire, including tacks, nails, and thorns.  The idea is that it typically takes several tire revolutions for such debris to penetrate the tire, and if you can knock it away, it won’t puncture the tire.  These typically mount (e.g.) the same place as the brake calipers on a bike, which means that you’d have to device a custom mounting for use in a wheelchair.

Emergency pump:  C02 inflator or Standard bike mini-pump plus long adapter hose.

Based on what I read on the internet, plenty of wheelchair users adopt standard bike mini-pumps for tire inflation.  These pumps are capable of reaching the (e.g.) 140 PSI required for high-pressure tires, but tend to be slow to inflate a tire, because of that.

The main drawback that I see, for on-the-go use, is that most of these pumps require direct attachment to the valve stem. That means that the user would have to hold the pump to the side, stabilize it on the wheel, and pump up the tire in that awkward position.

I think it’s far easier just to add a two-foot air hose, readily available from Amazon.  That would allow a person seated in a wheelchair to inflate the wheel by holding the pump comfortably in the lap, rather than leaning over to manipulate a pump directly attached to a valve stem.

But by far the most obvious solution is a C02 inflator.  These are compact enough to be held in one hand, and so should be readily usable by a seated wheelchair user to inflate a low tire on-the-go.  A single small (16 gram) C02 cartridge should be adequate to bring a 24″ x 1-3/8 tire up to a reasonable working pressure.

A battery-operated rechargeable tire pump is a distant runner-up.  Most of these are relatively bulky.  Many of the less expensive ones cannot generate high pressures.  And even with that, the batteries would slowly self-discharge, meaning that the user would have to remember to charge the pump periodically.  That’s just begging to find that the battery is dead, just when you need it the most.

Conclusion

For pneumatic wheelchair tires, periodic maintenance of tire pressure isn’t much of an issue.  Reliable plug-in electric inflator pumps capable of 100 PSI are readily available.  These can be had with reasonably long air hoses, allowing the user considerable leeway in hooking the pump up to the valve stem.  All that is required is remembering to use it on a regular basis.

The big problem is flat tires while out-and-about.  There, many of the off-the-shelf solutions available to bicyclists — in-tire sealants, puncture-resistant liners, run-flat tires, and “tire wipers” — are not available (off-the-shelf) for narrow, high-pressure pneumatic tires typically used on wheelchairs.

That only leaves puncture-resistant tires and tubes.  Those may slow down the rate at which flats occur, but neither of those will stop sharp metal objects such as tacks, nails, or screws.

I guess my bottom line is this.  If you can tolerate the occasional flat tire, then go with high-end “puncture resistant” tires and tubes.  Forget Slime (r), tire liners, tire wipers, and similar makeshift solutions.  If not, I’d go with solid-rubber tires (not inserts), along with the steel bench-mounted tool used to install those tires safely on wheel rims.

Post #1908: I returned a broken jar of jam to Amazon today …

 

… and I’m still not quite sure how I feel about that.

I packed it in something leak-proof and put a Post-It on it saying “broken glass”.  But I didn’t even need a box, as I dropped it off at the Amazon returns counter at my local Whole Foods.

But …

Shipping a broken jar of jam is clearly fundamentally stupid.

And yet …

Shipping a broken jar of jam was the right thing to do.

I will now outline the whole series of events, so that I may justify to myself what I just did.  But it boils down to “there’s no way to tell Amazon that I should just toss this in the trash”.

So … you want your money back, you want to play by the rules?

Then you ship them back their broken jar of jam.

Do be do be do

Amazon gives you the option of having a week’s packages all delivered on one given day.  Friday, for me.  That’s instead of having different orders arriving throughout the week.

Trying to be a good do-bee, I take them up on that option. Particularly at this time of year, when I’m ordering Christmas presents.  I do it because I think it’s (ever-so-slightly) more environmentally friendly, but mostly because it cuts down (for Amazon) the total work involved in delivering my packages.

I’d guess that means a greater likelihood of getting a large carton packed with multiple unrelated items.  (Compared to having items arriving on different days.)  But I’m not sure about that.

At any rate, today’s shipment had a $10 jar of fancy jam, broken, inside a multi-item carton.  The carton had a lot of empty space with no filler material.  Not a good plan when you’re shipping glass jars.  The only thing that prevented that jar from painting the inside of the carton with jam was a single layer of bubble wrap taped around the jar.  As it was, I had to sponge smears of jam off the rest of the items in the box.

Despite this, I still think having all your Amazon packages delivered one day a week is the do-bee way.  When feasible.  But I might reconsider that after this event.

What to do about the broken jar of jam?

Amazon returns

So I go on-line, to get Amazon to send a replacement or refund for that $10 jar of fancy Christmas-present jam that got smashed.

Amazon says, sure old buddy, no problem.  When are you going to return the first one to us?

And I’m like, return it?  God no.  That’s just plain stupid.  It’s a mess.  Its a smashed jam jar, held together by leaking bubble wrap.  It needs to go straight into the trash.

On the Amazon on-line form, there’s no check box for that.  Or anything like that.  No option for “trust me, you don’t want this back”.  If I want a replacement or a refund, I need to return it.

I know that, in theory, I can somehow get in touch with somebody at Amazon and they may OK a refund without the stupidity of returning the jar of jam.    But I didn’t want to go to that effort of working my way through their customer service process trying to find somebody to do that for me.

(I once had an empty package delivered from Amazon.  You think it’s tough returning a broken jar of jam, try returning the contents of an empty package.  That’s how I know that if you can find a human, you can at least sometimes get an exception to what’s shown on the return form.)

And as an economist, I can see that’s its an open invitation to criminal abuse if you let people easily claim a refund without returning the items refunded.  So I have no problem at all if Amazon wants you to have to jump through hoops to do that, as a matter of course.  I just wasn’t up to hoop-jumping today.

What to do?  To get my money back,  I have to ship a broken, oozing jar of jam as if it were merchandise.

Either that, or cut my way through Amazon customer service.

Shipping it is, then.

Nesco to the rescue

One uses the gizmo pictured above, plus special plastic bags, to produce vacuum-sealed food.  Or, in this case, vacuum-sealed garbage.  The bags are heat-sealed (i.e., melted shut), and so are leak-proof as long as the seal doesn’t fail.

I duly sealed the broken jar (bubble wrap, oozing jam, and all) inside a seal-a-meal bag, along with two big sticky notes saying “Broken Glass”.  This, to prepare it for its journey back to Amazon.

I then drove to my nearby Whole Foods, and handed that over the Amazon return counter there.  If you return it that way, you don’t have to pack it in a box.  Whole Foods staff handle that in some fashion.

The guy at the counter was, I think, the biggest person I had ever seen working a counter at Whole Foods.  Big and tall, like a college linebacker.  Neither here nor there, merely unexpected.  The Whole Foods clerks in this area tend to be fit 20-somethings.  This was like seeing a bear onstage among the ballerinas.

I let the clerk at the return counter know I was returning a broken jar of jam, with my apology for shipping back something that stupid.

He didn’t bat an eye.  Took the package, scanned the QR code Amazon had given me (displayed on my phone), and said I was done.  As far as Amazon was concerned, it has been returned.  They’ll send an email shortly.

The entire return transaction took about ten seconds.  He practically had to shoo me away, as I stood there in disbelief.  I thanked him profusely, and walked off to pick up a few grocery items while I was at a grocery store.

In any case, when I decided to return it, I was betting that this ridiculous return has relatively modest environmental impact, relative to just tossing it in the trash.  The fact that you don’t have to box your item probably means that they fill a bin with returns, at Whole Foods, then everything gets trucked to some Amazon return center.

I probably used no more than one KWH for the in-town round trip to the store, which would equate to about 0.65 lbs C02 emissions here in Virginia.  Full trucks, by contrast, are vastly more efficient than empty autos, for moving freight, on order of 100 ton-miles per gallon of fuel.  Pro-rated to my 12 ounce jam jar, the fuel cost from Whole Foods back to Amazon was nugatory.  So I’m hope-guessing that the entire return trip “to Amazon” resulted in release of less than a pound of C02.  If I’d decided to toss that $10 item in the trash and take the loss, for environmental reasons, that would have worked out to a ludicrous $20,000 per ton C02 avoided.

That in no way suggests that it’s smart to return a broken jar of jam to Amazon.  It remains fundamentally stupid.  It’s just that if I’m going to burn up $10 to save the environment, there are for more effective ways to burn it.

This takes no account of the effort and energy expended after this broken jar of jam gets back to Amazon.  I have no firm idea of what happens after I hand my return over the counter at Whole Foods.  Presumably, between my reason for return, the big yellow stickies inside the package saying “Broken Glass”, and the purple goop encapsulated in the vacuum-seal bag, oozing around the bubble wrap, somebody along the line will have the good sense to throw this away.  It’s just a question of how much effort it takes to do that.

The upshot is that, no matter how stupid it seems, returning the smashed jar of  jam to Amazon was not a particularly bad thing to do.  (Assuming my sanitary packing holds up.)  It turned out to be almost no hassle, given that I owned a vacuum sealer (though a zip-lock might have been acceptable too, for all I know.)  Tossing it in the trash, solely to avoid C02 emissions, would have been ludicrously inefficient.

Plus, damnit, they owed me a new one.

Will I ever see this jam again?

It got me to wondering.  In Amazon comments, you will frequently (enough) read of somebody who claims to have gotten an obviously used item sent to them as a new item.  The presumption is that the vendor got a return, and sent them a returned item instead of a brand-new item.

I now wonder about the extent to which this is an urban legend.  Or not.  I see it enough, from a wide enough variety of people, that I’m thinking it’s true, and not an urban legend.

And sure enough, here’s what a CNBC article says about those returns.  Amazon will return the merchandise to the seller, at the seller’s option.

When an item can’t be sold as new, Amazon gives the seller up to four options for what to do with returns: each with a fee: Return to Seller, Disposal, Liquidation, or (by invitation only for now) Fulfillment by Amazon Grade and Resell.

Presumably, the original vendor can tell Amazon (for a fee) just to dump this particular return.  And this whole sad episode will come to a close.

Closure

Is it any wonder that I am increasingly baffled by the modern world.

Shipping a broken jar of jam is clearly fundamentally stupid.

Shipping a broken jar of jam was the right thing to do.

In any case, it’s Amazon’s problem now.