cyccommute 

The gains in rolling resistance are also lost in the noise for commuters, especially when commuters go to very wide, very heavy tires. For a racer, going from a 23mm to a 28mm result in a 5% reduction in rolling resistance. At 15 mph, that's 5% of approximately 5 watts or 0.25W. That's enough if you are trying to be faster than someone else by a few hundredths of a second but at the same speed, you are exerting nearly 100W against the wind on a racing bike and probably closer to 120W on a "typical" commuter. 0.25W is 0.25% reduction in the overall energy you have to use to push the bike down the road. You need a 5% reduction to notice the difference. And you've upped the weight of the bicycle so the energy requirements are higher.

My load is attached to the bike when I commute and when I tour. My touring weight is significantly higher than most people would use for a commute...although I've seen commuters carrying an awful lot of stuff. Even with that heavier weight, I can not only unload the rear wheel while riding, I can loft it up a curb with a commuting and touring load. As I said I even off-road on my commute at times and I still carry stuff on the rear rack.

It is not impossible. It's harder with platforms...which is one of the reasons I don't ride platforms...but even there if you know the tricks you can bunny hop a bike with platform pedals...with a load.

cobrabyte

and what a load, indeed

Bike Gremlin

Fat tyres let me not need to bunny hop at all.


Do you know any videos, or links on how to? I have problems bunny hopping with platforms when bicycle is loaded and the seat is not placed lower than it should be for riding. If it's possible, I'd like to learn and practice it.

Andy_K 

OK. Here it is:
[/LIST]

That's my point. So when you "simply pointed out that skinny tires aren't faster than wide tires" you were failing to take into account the actual tires available. If speed isn't a priority that' fine. I commute on 700x35 tires because I agree. If I wanted something faster, I'd need something skinnier.

Leebo

I like fat tires and I can not lie.... I value traction and comfort over speed. My slicks are 700 x 35 on the Crosscheck. The big tires are on my Karate Monkey. 29x2.3's on 35 mm rims. BIG. The ability to pedal dirt on the ride home trumps all.

PaulRivers

Yes, you're accusing me of doing what you're doing in your post.

Like I said, the experiment you're referring to proves that when going downhill heavier bikes are faster, and fatter tires are heavier, both of which are not disputed.

cyccommute 

Back it up. Show me where I'm wrong.

cobrabyte

Or I could live in reality and not do that...

cyccommute 

You only think that fat tires allow you to plow through anything. Some day you are going to come across a hole that will either break a rim, break a frame, cause you to crash or all 3. Here's a link that has text and video. You only have to get the rear wheel off the ground a couple of inches to clear most anything on a smooth(isn) road. It's easier with toe clips or clipless but it can be done with flat platform pedals as well.

cyccommute 

All hat. No cattle.

cobrabyte

You have no argument for me to debate against. It's all conjecture, no evidence. What studies can you provide links to that support your claims?

Jaywalk3r

Agreed. I was just disputing the false claim that skinny tires are faster.

Only for the acceleration. Weight doesn't affect the energy required to maintain the speed. More energy is needed for climbing, but more potential energy gets stored.

Bikes well-suited for commuting are often ill-suited for bunny hopping, clipless or not.

Jaywalk3r

Yes, because it has zero to do with how tire width affects tire speed. If you want to argue that some tire models are faster than others, I would agree, but it isn't relevant to the discussion. One simply cannot change multiple variables and then attribute all of the effects to only one of those variables. (Technically one can, but any resulting conclusion is without merit.)

Jaywalk3r

Incorrect. The differences observed are far too large to be attributed to a tiny percentage weight increase.

Bike Gremlin

I stand corrected: I can get over MOST (99%) of the obstacles, holes, bumps, kerbs that are in my path where I usually ride. The ones that would damage even a 40mm tyre wheel are usually more visible (not always - I avoid puddles like a plague, never know what's beneath).

As far as video goes: those seats are WAY lower than I ever ride when commuting. That's a MTB, off road setup bike. But on a seat that is at the correct height for road riding, it would be impossbile to do a bunny hop with platform pedals. And a backpack packed at the rear rack. So when I need to go up a 5 cm tall kerb, I highly prefer a 40 mm to a 23, or even a 28 mm fat tyre. The 40mm ones don't even need any slowing down for the kerb. Same goes for most smaller pot holes, bumps etc.


With all the extra weight I already carry when commuting, a 100 gram difference per tyre is really irrelevant. Even though it is a rolling weight and hence multiplied a bit. Same goes for rolling resistance. My commuting times don't change much. What affects me most is the riding position - strong wind is the biggest problem in the flat lands I commute.

Andy_K 

If you're only interested in the theoretical aspects of the discussion, it has zero to do with it. If you're actually trying to choose a tire, the actual tires available are kind of important to the decision making process.

Jaywalk3r

Agreed. And this discussion has been about how tire width affects tire speed, not about the effects of threads per inch or flat protection.

If someone wants a wide, fast tire, those are certainly available. Avery quick search revealed the Schwalbe Kojak and Super Moto. There are undoubtedly others from other manufacturers.

spare_wheel

I think just about everyone agrees that larger tires have better rolling resistance under ideal conditions and at the same PSI. However, I run 25 mm tires at ~110 psi and my 37 mm at ~60 psi. And since I have relatively smooth pavement for most of my commute the higher psi translates into a significant decrease in rolling resistance. I also personally find the 25 mm tires to be just as comfortable as the 37 mm.

Jaywalk3r

And in real world conditions at lower PSI.

Andy_K 

I haven't tried either one, but I'd be shocked if they rolled as well as a typical skinny race/training tire. Schwalbe gives them a very high rating for speed, but they use a different scale for rating their city/touring tires than they do for their road tires. That is to say, Schwalbe's claim is that they are fast for a city tire.

I'd really love to see something comparing a 700x35 Kojak to a 700x25 Ultremo or even a Durano. Having used Ultremos, I can tell you that they roll like butter. They also resist flats like butter. Schwalbe rates my 700x35 Marathon Supremes at 5 blocks for speed (just a step down from the Kojak). They roll great for a city/touring tire, but they're nowhere near the Ultremos in that regard. On the other hand, they're way more durable and puncture resistant.

bobbyl1966

It is okay put the max pressure on the tires? Example when one tire say max pressure is 120psi is okay use 120psi? The innertube is can hold that pressure? Or is the tire have pressure limit. And the innertube can hold much more pressure than 120psi?

spare_wheel

Nah...in the real world of the average commuter tire choice is more of a personal preference than a performance issue.

Jaywalk3r

True, but that doesn't change the fact that wider tires still have lower resistance in real world conditions. There's really no downside to wide tires for commuters.

trailmix

Monthly train wreck, all aboard!!!!!

spare_wheel

It's OK to use max pressure and it's the seal of the tire with the wheel that matters -- not the tube. (Higher pressures are not always more efficient and can feel harsh to some.)