On Wednesday, January 11, 2017 at 8:41:13 AM UTC-8, wrote:
On Tuesday, January 10, 2017 at 8:04:57 PM UTC-8, jbeattie wrote:
On Tuesday, January 10, 2017 at 7:28:41 PM UTC-8, Frank Krygowski wrote:
On 1/10/2017 4:11 PM, wrote:
But light bikes do NOT make hard climbs much easier. In fact they add a lot of problems. Once the grade gets up to 18% you can't use low gears because on the light bikes it will lift the front wheel off of the ground.. The bike will then pivot around the rear wheel and if you're ready for that you can lay the bike over before it turns down hill.

The way professional climbers get away with this is that they use LARGE gears. Then you don't have the leverage to lift the front wheel.

I think you need to draw a free body diagram of the forces involved.

Sure, you can pop a wheelie on a steep grade if you put too much weight over the rear wheel on a short wheelbase bike in a super-low gear -- but you can do that with a steel bike, too. That's why you move your weight forward a little -- but not so much that you lose rear traction.

Professional climbers do not use LARGE gears. Post-Lance, they spin. My son was on the crew for the Tour of Utah and was surprised that a lot of domestic and Euro pros were using low gears. Here's a photo that he took: http://tinyurl.com/hpztj3o That ride has some staggering climbs with 20% grades.

Jay, take out a CX bike with super low gears on a mountain bike course with extremely steep sections just one time and you'll see what I'm talking about. Then use this same bike on steep asphalt sections and it is so plain that you can't miss it.

You have to shift your weight to avoid the wheelie effect. I commute on a CX bike and ride steep hills every day on asphalt and dirt -- including a dirt trail that goes straight up next to a set of steps. It is over 30%. I ride that on a 34/26 -- which is my low gear on that bike, but I do it out of the saddle, fairly centered until I bog down and lose traction (I also encounter a barrier). I ride steep asphalt in the same gears on the CX bike, but usually out of the saddle for the steepest parts. I have a Roubaix that has a 34/28, and it will wheelie if I don't move forward a little. I'm not disputing that you can get the "light front end" wobble or wheelie. You just have to change your riding position. BTW, I sometimes ride the steepest street in America and perhaps the world -- which is not too far from my house. http://offbeatoregon.com/H1010b_oreg...st-street.html These dudes are preparing for the epic climb: https://www.flickr..com/photos/gabri...995/?ytcheck=1

-- Jay Beattie.