Tuesday, June 24, 2008

It just feels right

Building a responsive bike for the urban criterium calls for a careful balance of factors.

Riding traffic, a rider wants to sit up enough to look ahead and keep track of a complex situation without straining. An explosive sprint can come in handy, but the position for a good sprint requires low handlebars and a grip nearly even with the steering axis of the bike. Frame geometry helps make a bike stable under hard acceleration as well, but even a good tight frame will feel waggly if your bars are too high, your hands too widely set and your grip too far forward.

Drop bars have the drop position back by the head tube. That way, sprint force goes straight down the steering axis behind the contact patch. Sprinting from a high forward position sends your force back down the stem to get to the steering axis. While the bars hang just as far forward of the stem no matter where you grab them, your weight stays more centered between the wheels when you're on the drops. You're also able to pull up against the stem with more leverage and more centering counter-force than when you sit up or pull on bar extensions that are high and forward.

I left the fork on Blue long enough to set the bars higher than on any of my other road-oriented bikes. It feels really mellow when I'm sitting down sitting up. If I stand to sprint I have to remember to keep myself back and only stand for a couple of pedal strokes. The bike is light and accelerates readily, so I can spin it up pretty quickly. But it robs me of the fight-or-flight burst I can use on the other bikes.

Trying different options, I dropped the bars a centimeter. Suddenly it felt more capable. When I compared, I found that this exactly matched the bar height on my other bikes. I'm so accustomed to it that I could feel the difference without knowing what it was.

Different doesn't mean wrong. I wanted to be able to sit up more, even if I didn't have the bike set that way all the time. I left the bars in the lower position for now, but left the steerer long enough to move them up again when I want that.

Maybe I'll ride to town with no brakes tomorrow and scrounge some brake levers that fit my bars. Blue is very fun to ride.

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