aboylikedave

Hi there

I'm commuting on a Trek 7.5 and was using Bontrager Racelite Hardcase 700 x 28, 105 psi. I'm about 75kg and it's a very hilly ride. When these needed replacing I changed to Conti Gator Hardshell Folding 700 x 25 115 psi.

They are (according to specs) lighter and are narrower. When I put on the rear it felt great but as soon as I put on the new front, the weird thing is it really does feel harder to pedal!!! And I mean noticeably.

Is there any possible explanation other than being purely psychological? Apart from me ageing rapidly!

Cheers

Dave

unterhausen

Bike Quarterly has done studies of this issue, and found that thinner tires often have higher rolling resistance.

tjspiel

Tires are complicated. A lot of the energy lost through the tires comes from flexing the sidewalls. That's one reason why higher pressures make for easier rolling, - less sidewall flex.

Wider/bigger tires tend to lose more energy in sidewall flex than narrower ones. Narrow tires also have less frontal area which makes them more aerodynamic. This matters more at higher speeds.

Tread patterns and tire construction also make a difference so it's very possible to make a wider tire that performs better than a narrower one especially when we're only talking about a few millimeters difference.

sggoodri

Higher pressure and less rotational inertia usually ease pedaling significantly. Road vibration may be increased, which could increase hand/arm fatigue.

groovestew

It probably shouldn't feel noticeably harder to pedal. Probably a stupid question, but did you install your front wheel properly? Check for a rubbing brake pad.

tjspiel

Probably a good thing to check. Unless you're going from a skinny slick to a fat knobby tire I doubt the difference would be that noticeable.

somedood

2nd agreement here. Make sure the wheel is all the way in the fork's dropout and that there isn't any brake rub. There was a study showing that identical tires at 23mm and 25mm (at the same pressure), the 25mm had slightly less rolling resistance than the 23 - I'm not sure if it would be discernable by a human, though. The hardshell's may be a tiny bit stiffer tires than the hardcases, but if you're noticing resistance at 10psi higher pressure than the old tires something else has to be wrong.

aboylikedave

No rubbing or wheel restriction. I appreciate you asking the 'stupid' question

10 Wheels

Lift the bike up and spin the front wheel.

waynesworld

Yes, do this. And, just for fun, do the back too. From what you've said, it really doesn't make sense that it would be the tires.

Seattle Forrest

I never really liked my Gatorskins, but they weren't terrible. I'd pick the bike up and spin the front wheel, too...

wolfchild

I feel it's much easier to ride on 700x32's, then it is on 26x2.00. I have pretty much given up on 26 inch wheels and fat tires. I prefer 700cc with narrower tires, when I say narrower I mean anything from 28mm to 40mm. Bigger wheels with narrower tires are less work on pavement then smaller wheels with fat tires.

aboylikedave

Yes, no restrictions. I even spun it with the brakes off to check.

waynesworld

Beats me then. I think the Bontrager Hardcases are very hard, uncomfortable tires, but they do roll well. I've never ridden the Gatorskins, but I cannot imagine why you are experiencing what you say.

aboylikedave

For the record they are Gator Hardshell, not Gatorskins. Newer tougher tyre.

imi

In a couple of weeks or so I'll be A/B testing Gatorskins against GatorHardshells. Two virtually identical wheelsets (commuting/touring) changed on the same bike. I'm interested to see if I'll be able to feel any difference. Both tires look and feel identical. The Hardshells weigh slightly more due to the added sidewall protection.

I'm expecting them to perform very similarly but will test with open mind. I would be very surprised if the Hardshells feel like tanks... I'll post my subjective findings.

somedood

The weird part is the front should have less weight on it, so less rolling resistance. If you put the tire on the back and it felt great, but put on the front and it felt sluggish still makes it seem like it could be something else. If you put the old tire back on does it feel a lot better? Are you feeling slowness while climbing, accelerating, or just trying to maintain speed?

I went from some vittoria rubino pro's to continental gatorskins in 23mm (the conti's are heavier) and barely notice a difference. Is the front inflated to 100+ psi?

BarracksSi

OP, you aren't binding the hub bearings via some other misadjustment, right?

old's'cool

Can you please explain how less rotational inertia eases pedaling?

fietsbob

Accellerating , changing rates of speed and climbing. JRA with no changes much less..

unterhausen

I am not sure I can tell the difference between tires, but the Gatorskin hardshell do feel little slower than the regular Gatorskin to me. I don't have them on the same rims though, the rims the hardshells are on are considerably narrower.

old's'cool

agreed,... "changing rates of speed" = accelerating; in the upward direction, more rotational inertia makes pedaling harder; in the downward direction, presumbably you aren't pedaling anyway.


Please explain how less rotational inertia eases pedalling while climbing.

2manybikes

It makes perfect sense. You are feeling what is happening correctly. As you get going faster the thin tires will do better.

Wider tires have less rolling resistance than narrow tires. It is because of the way the sidewall flexes. If I could draw a picture here I could explain it better.

Better rolling resistance is noticable at slower speeds. As the speed increases the rolling resistance does not change, but the weight of the tire you are spinnning becomes more important (thiner tire will do better) When you go even faster, the rolling resistance and the weight does not change, but the aerodynamics of the tire and rim becomes more important (thiner tire does better). Wider tires ( if everyting else is the same) willl roll better from a dead stop down a hill.

waynesworld

I'm looking forward to your findings.

somedood

I don't know that a person would be able to detect the change in resistance, though. My bike with 28mm gatorskins does not feel at all like it rolls any easier than my bike with 23mm gatorskins, even at the same tire pressure. Generally a narrower tire will be able to run at a higher pressure which means less surface area to deflect anyway.