Sy Reene

Yeah.. I'd guess 90%+ of road cyclists use a gauge as most presta pumps have one built in, or put another way, the $10 upcharge for a pump that has one vs one that doesn't, is probably a somewhat decent investment.

ThermionicScott 

autonomy

https://www.topeak.com/global/de/products/floor-pumps/221-joeblow--sport-ii which I got on sale. The gauge isn't very accurate but good enough for me.

My travel pump, road morph, also has a gauge, again, not very accurate but good enough.

I notice quite a bit of difference in speed and comfort between 90 and 100 PSI, and I bet very few people would be able to tell 90 vs. 100 "by pinch"

I mean, if you care enough about stats and 28 vs. 21 mm, why wouldn't you use a gauge? Kind of like running a medical study and not normalizing for things like age, race, etc.

wphamilton

To me it's not all that simple, but even if we think of the entire difference in wear, front tire and back, as being a result of abrasive wear then it boils down largely to the back tire sliding. Even if you think of localized areas sliding rather than the entire contact patch, still sliding. In this case the weight distribution is a large factor (one tire slides, the other does not). As well as riding style, road surface, speed, amount of braking etc etc. I'm not so certain as you that weight distribution doesn't impact these factors to that degree of 2x to 3x faster wear.

ThermionicScott 

A tire doesn't have to be wildly skidding to generate the abrasion we're talking about here. Simply working the bike up to speed from a stop, over and over again, causes wear that the front tire doesn't ever see. If you think weight distribution is the major factor, how would you explain tandems like Carbonfiberboy's (and many others) which wear out the rear tire much faster than the front despite equal loading? I can't believe we're even discussing this.

Oh wait, I can. This is the 41.

Kontact

A factor that this argument is ignoring is the way the front and rear wheels interact with the road. I've never seen the front tire wear flat like the rear always does, because the constant steering distributes wear more.

I also agree with wphamilton that weight vs wear is unlikely to be a linear relationship. It is probably a lot more like wind resistance, and wear increases geometrically to weight.

big chainring

How a tire wears...thats an exiting debate.

wphamilton

I don't know that it's unlikely to be linear, since at first gasp you'd assume that abrasive wear is proportional to normal force. I just think that there's reason that it might not be, and I'm not certain how large a part the rubber wear (hysteresis etc) plays and whether that's linear with load. It might be. He seems to believe that weight distribution plays no part at all, and that his opinion is so self-evident that it need not be challenged.

He also transformed "a large factor" into "the major factor", ignored that I proposed a function of "As well as riding style, road surface, speed, amount of braking" and then mocked that anyone would discuss what he came up with for me to say. Looking at some of the published models of tire wear, I don't think that *I* can fully understand them without some study, much less explain it to someone that would be resisting it. I asked him "why not" because I thought that he might know something specific about it.

big chainring

This is like watching paint dry. Go start your own thread.

ThermionicScott 

ThermionicScott 

Sorry to offend @wphamilton. I honestly thought you were making a serious-sounding joke, what with that "tires wearing the road" bit at the end. I'm sure weight has some effect in the whole thing, but that will be confounded by inflation pressure and tire width for the load, too.

wphamilton

NP. It WAS a half-joke since pavement compression is obviously different from pressure on rubber, but half because it's hard to ignore that fourth power exponent of weight. I was just asking.

wphamilton

Far be it for me to derail "21's are faster than 28's", sorry.

RChung

I used to be on the bicycle subcommittee of our local public works commission, so I've had discussions with our civil engineers about road conditions and road wear. They use the 4th power of axle weight * the volume of traffic to estimate road wear. A loaded bus or 15-ton trailer puts about 100x as much load per axle as a cyclist. (10^2)^4 = 10^8, or around 100 million. This came up in a discussion about how much cyclists should pay for wear and tear on roads. A 3000 lb. car puts around 50,000x as much wear on the road as a cyclist.

WhyFi

And few 'Mericans would would suffer the indignity of such a toy.

rm -rf

Yes, the back tire wear is just about all due to pedaling force. I can even hear the tire when I'm standing up and accelerating hard. Powerful riders will wear out their back tire sooner, too.

Other factors: leaning over, more weight on the rear tire, are a tiny fraction of the pedaling wear. And braking would wear the front tire faster, not the back.

Kontact

Your distribution is 45/55 only when you're seated on a level road. Every hill shifts your weight, riding out of the saddle scrubs the tires more.

It would be interesting to look at Triathlete tires in flat states - weight distribution is closer to 50/50 and there's no climbing.

big chainring

I'm totally amped. I am achieving a new level of performance. I think its the 177.5 crank length along with my 531 Wolverhampton Wonder. Skinny tires juiced to a higher pitch psi. I'm trimming seconds from my Strava personal bests and banking KOMs. My watts are amping up and becoming volts. Crushing it. Twice I cat 6ed it on the MUP against the local carbon fiber boys. Their bikes literally 'sploded as my Viking ship sailed by them. Just ordered some vintage Clement no. 1 silks from a monk in Rocamadour, France. Aged 40 years in a cave like fine wine, stored on Padauk wood rims that lend a reddish hue to the Egyptian silk threads. Most likely will cut more time from my TT runs.

noodle soup

f4rrest

...lost them at "fourth power" I'm afraid.

merlinextraligh

did you recalibrate your computer? the circumference of a 21mm tire is less than 28mm. So without recalibrating a traditional cyclocomputer will read too fast and too long with the smaller tires.

Abe_Froman

That would be really funny if that's what actually happened lol. Instead of switching to the right circumference, he should just to to KPH and pick up another 50% speed.

anon`

Now just wait until your watts starting volting up to amps! Also, good call on that Wolverhampton over the Bolton.