MikeEckhaus

Looking for a new ride. I like the new endurance oriented machines. I just test rode both of the mentioned bikes. 35 miles on the BMC and 65 on the Trek, many of the same roads. What I noticed was that the BMC seemed to absorb small bumps and vibrations much better than the Trek, but the seat tube pivot helped the Trek on bigger hits. I am wondering if the small bump absorption of the BMC was due more to it having 28 mm Contis on it than it was due to the frame kinks. The Trek had 25 mm Bontrager R3s. The BMC had Easton EA90 wheels vs Racelites on the Trek. Unfortunately I do not know the inflation pressures of the tires. Neither was tubeless.

I also noticed the Trek was snappier on acceleration, but again, I am wondering if this was due to lighter wheels vs a stiffer chassis.

Both bikes were great rides. Hoping the experts can shed a little light on my observations. And please, no Trek hater comments, I am just interested in opinions of tires vs frames on my ride observations. Thanks.

fa63

In my experience larger volume tires do make a big difference, especially with smoothing the small bumps and vibrations. However, there are many variable between tires (construction, quality, etc.), not to mention the frames and wheels, so the only way to really know if the Domane will handle the small bumps and vibrations as well as the GF01 would be to take it out on another test ride with the 28 mm tires. Can the bike shop just swap out the wheels for you and let you go on another test ride?

MikeEckhaus

Fair question but the bikes were from different shops and had whatever was stock on them. In a perfect world, I could have put my wheels and tires on both, but one was an 11 sp, which would mean cassette swaps etc. plus I wasn't smart enough to think of that at the time ;-)

hueyhoolihan

IME, it's all about the tires. mostly the width and PSI.

with seven road bikes, and with frames from 1979 to 2013 and from lugged steel to TI, to AL, to carbon, i can easily, turn any one of them into a riding nightmare.

warpdrive

yes, the tires are everything when it comes to ride comfort over jittery bumps...tire PSI, width and RIM width affect the way the tire deforms over bumps. The tires will affect the buzziness of the frame over bumps far more than any differences due to carbon layout or frame construction. I had two sets of the same wheels on my previous bike and just a tire change alone completely changed the feel of the bike. One was buzzy and one was so supple, it felt like it was low on air even though the tires were cosmetically similar (both 120psi tires with minimal tread) and nearly the same weight.

Having said that, the isospeed does seem to be effective especially in the 5 and 6 series....I test drove a few endurance bikes and the difference was noticeable right off the bat. I really wasn't in the market for a Trek this time around but for an endurance bike, I think they are really onto something with this design

rm -rf

That's interesting that the BMC comes with 28c tires. That's usually a size used on touring bikes. And they are using expensive Continental GP4000 tires, a very flexible tire, instead of the usual cheaper, stiffer tires that often come with new bikes. The air volume and the tire flex combine to really soak up the bumps in the road.

A few years ago, a BF poster had some good ideas on how to test ride bikes. One important idea was to always fill the tires to the same psi before each test ride. It's harder to do when the tires are different sizes. I would try 105 front, 110 rear on 23c; 95 front, 100 rear on 25c, and maybe 85-90 front and 95 rear on 28c. Add 5 psi to these if you are over 200 lbs.

It's all about the volume of air within the tire. Years ago, even 25c tires were only on the more upright, comfort oriented road bikes. Now, many riders are finding that 25c tires are just as fast as their old 23c tires. The other trend is to wider rims, to increase the air volume on 23c tires to make them ride more like 25c.

KantoBoy

the GF01 was developed for the Cobbled races and for touring where comfort is the #1 priority.

Thor used it during last year's Paris-Roubaix.