Wednesday, February 2, 2011

Go fat...

For years, I rode with 23 tires on my road bike. Always inflated to 100 psi front and rear. At about 170-175 lbs., I felt that pressure was perfect for me. And Bernard Hinault told me. About 5 or 6 years ago, I designed one of my favorite all time bikes for Masi - the Speciale Carbon. It was made in Italy and featured Dedacciai steel tubes with Dedacciai carbon seat and chain stays. It's no longer available and that's a shame. On that bike, I installed a set of WTB road tires they gave to me way back when. The tires were labeled 25, but actually measured 26mm. And they rode great.

Fast forward to today and I'm running Continental 4-Season 28's on my road bike inflated to 78psi in front and 80psi in back. I don't lose any speed (that I have) and they are uber-comfortable on the road. I'm using a rim that's a bit wider than the standard skinny road rim. The wider rim gives the tires a nice profile and contact patch and helps to brace the structure of the tire so it doesn't fold over under cornering forces.

However, riders and bike companies still seem to think the 23 inflated to max pressure is the way to go. Maybe that will change. In the mean time, there is a lot of information coming out that refutes the skinny/super high pressure thinking. Think what you want about Bicycle Quarterly and their seemingly narrow focus, but they have some pretty good tech articles and this one on tire pressure is pretty good.

And now, I've been reading some good stuff by Nick Legan, a former pro mechanic (well, once a pro mechanic, always a pro mechanic) at This one on tire pressure is good. And the link he posted to the Sheldon Brown's All About Bicycle Tires And Tubes is excellent as well. And then today on, there's a piece on the work of Wheel Energy that claims during testing, wider tires roll faster than narrow ones.

With all this out there, why do riders still insist on running their 23 tires at 120psi? You've tailored your bike to fit you by spending upwards of a couple hundred bucks for a pro bike fit. Why not get tires that fit you and run them at the proper pressure? You bought a stem to get a better fit. Get tires that give you a better ride. One of my analogies is to compare the air pressure in your bike tires to the air pressure in your car tires. Your car tires have a max pressure of around 50psi, yet you run them at around 32psi. Try inflating your car tires to max and then take it for a drive. The ride quality will be horrible on the road. The same holds true for a bike tire.

A lot of the crop of carbon road bikes are made with minimal tire clearance. Some can't physically fit a 28 between the stays or under the brake caliper. Run a 25 in that instance. I guarantee if you run a bigger tire on the road at the proper pressure, you will be more comfortable and in being more comfortable, you will be fresher feeling during your ride. And fresher means faster.

(What's playing: Led Zeppelin Good Times, Bad Times)


Anonymous said...

Great informative piece (as so often!). Can you make the link to the article on tire pressure work, please? It's always fun trying new larger tires, Ultremo's ZX 28's are out now.

Head Honcho said...

Nice post Mike. I've been trying to get folks around here to run larger/lower as well, and have had some success, but there's a few hold outs that just can't get over the high pressure = high speed component.

Gary J Boulanger said...

I run Continental/Hutchinson 25s inflated to just under 100 psi (as per the Badger) on my zippy steel racerboy bike, and Rivendell Jack Brown 33s inflated to 85 psi or so on my steel country bike. I weight between 183 - 190, so this is the formula that works for me.

Guitar Ted said...

That type of information was also put out by Schwalbe a few years back, and even further back, Continental also was espousing the use of wider road tires.

We've been telling folks pretty much what you have said here for years at the shop I work at, but the folk-lore behind the narrow/high pressure school of thought doesn't go away easily.

blackmountaincycles said...

Frank, the link is to a pdf that may take time to open. Here's the direct link:

My hope is that with more and more pieces about fatter/lower pressure being written on race sites like velonews and cyclingnews that the folks who need to hear it will pay attention.

Ben said...

I agree whole heartedly with everything you said. As GT said though, try telling that to roadies around here and they just dismiss you as a mountain biker. It's like pulling teeth. As you said, with so many bikes coming designed with 25c tires as a max size, it's not surprising that this is the case.

I give a lot of credit to modern road bikes like the Trek Fisher collection line that will fit 25c tires and fenders, or 28c plus tire sizes while featuring true road geometry still. However, I am not really hopeful that they will become popular soon.

Anonymous said...

There are so many variables in rolling resistance - surface conditions, tire pressure, rider weight, tire width, etc. Notice that on the CyclingNews article it says "all things being equal, the wider tire exhibits lower rolling resistance", well, sure a wider tire, pressure for pressure will deform less and have less rolling resistance, but pump up the narrower tire and you can achieve that same deformation level and the same rolling resistance, albeit with a rougher ride.

The key piece of information here is not that fat tires are faster, but for the same pressure they will be faster (and wider tires always get less pressure). So, wider tires offer more comfort for the same speed, it's not that they are faster overall, just faster for the same pressure.

Also, rolling resistance is a very small factor in overall resistance. Wind resistance is the big one, of course.

So, if you don't mind the rotating weight (the farther away from the hub the worse) and additional wind resistance (yes, wider tires will create more wind resistance) and want comfort then go for the fatties for sure.

Now, one more thing, on a really rough asphalt, the fat tire would win regardless since now it's not just deformation that matters. For smooth asphalt, the narrow wins.

blackmountaincycles said...

"There are so many variables in rolling resistance..." - So true. I do think that the majority of the weekend riders would enjoy the ride more if they had an appropriate tire size/tire pressure for their body weight. Doesn't make sense for both a 200lb rider and a 120 pound rider to run 120psi in a 23.

To me, ride quality and comfort trump any gain I would have by running skinnier higher pressure. I also love descending fast and find that for my weight, the 28's with 80psi are ideal.

I also think that a fatter tire at a bit lower pressure can change the ride quality of a harsh riding bike into a smooth riding machine. Thanks for reading and commenting.


TJC said...

Thanks Mike. Why do they call it common sense when it is so rare?

Anonymous said...

Great post. I personally run 25s and 28s on my road bikes, and love them, especially on the new 'wider' rims out there.

It seems that the bike industry is finally starting to take notice that skinny is not necessarily better, which is fantastic! Now if only we can get more of these frames designed to fit larger than 25s!