The Truth About Track Bike Geometry

Continued

most difference in the handling of the bike.  Now, I feel that the increased wheelbase in this frame doesn’t affect the bike in a negative way, but enhances the comfort in a long event, or even a road ride.

Lately I’ve noticed the trend for some framebuilders to utilize the 75° parallel geometry. This geometry isn’t really suited to everyone’s body and the events they might ride, nor for road riding. The wheelbase on this bike is now at a short 949mm, the equivalent of a bit more than 37 inches! (See the 75 Parallel illustration.) If you don’t ride your track bike on the track, this is probably why your body is sore after a long ride. The combination of added rake and a slightly slackened headtube would make all the difference in the world, increasing the wheelbase therefore creating a more forgiving ride. Something we all seem to forget is that riding a bike is supposed to be fun, not painful.

One thing that sprint and mass start frames have in common is a higher bottom bracket height. The typical road bike has a BB height of 265mm or the English equivalent of 10.45 inches. Due to the track having a steep banking in the turns, if you rode a regular road bike on the track you have a much higher possibility of scraping a pedal in a turn at low speed. Therefore on both mass start and sprint bikes, the BB is raised to 11 inches or a bit higher to eliminate the threat of a scraped pedal, although it still happens on occasion. This raising of the BB contributes to a bit of instability in the bicycle, which can be corrected with proper geometry. Pursuit bikes are kind of the exception to the rule, since they are rarely going slow during competition. They can have a lower bottom bracket, which also lowers the center of gravity making the bike more stable when using aero bars.

In closing, I would like to say that not all track bikes are created equal. I hope this handling lesson helps you understand modern track bike geometries and the differences between them.

Don Walker would like to thank Brent Curry at Bikeforest.com for the ability to use his program to illustrate this article.

Don Walker is a framebuilder and the founder of the North American Handmade Bicycle Show, which takes place in Portland Oregon this year, February 8-10, 2008.