![]() ![]() Unfortunately, these scenarios are hard to identify when doing a test ride of a bike and they can easily result in a smaller rider ending up with a poorly-fitting bike. At this point the effect of the shortened Effective Top Tube would be negated and both bikes would fit and handle exactly the same. In reality, however, the fore-aft positioning of the saddle should be determined relative to the bottom bracket and it’s likely that the orange bike would require a seatpost with significant rearward offset in order to fit properly. Indeed, the effective top tube measurement is shorter on the orange bike and the default saddle position will be closer to the handlebars. In the example above, the orange bike appears smaller since the seat tube and top tube have been shortened. This can mitigate Toe Overlap with the downside of placing the rider too far forward on the bike relative to the bottom bracket (or require that the rider adopt a more setback seatpost which negates the move towards a smaller size). One approach bike designers take to mitigate this is to scale down a bike by shortening the Top Tube Length without shortening the Front Center proportionally (or at all in some cases). Inconsistent Seat Tube AnglesĪs a bike design is scaled down to fit smaller riders, Toe Overlap (the tendency for the rider's toes to catch on the trailing edge of the front wheel when wide turns are taken) can become a problem. ![]() In particular, progressive mountain bike designs with slack Head Tube Angles are increasingly adopting steeper seat tubes in order to preserve ideal rider weight distribution between the front and rear tires, thus improving handling when climbing. Steeper angles are more common in bikes designed for a more aggressive, performance-oriented rider position such as Triathlon, Track, and mountain bikes. This accommodates the tendency for riders in an upright position to pivot their body rearwards. Slack angles are more common in bikes designed for a more upright rider position such as Touring, Commuter, and Comfort bikes. The chart above shows the distribution of seat tube angle for a selection of bike categories. This position is a major factor of bike fit and handling. Seat tube angle affects saddle placement which in turn determines the rider’s default position on the bike. This is not the only determining factor of saddle placement since it can be further adjusted by the choice of seat post and saddle. ![]() A “steep” angle moves the saddle forward while a “slack” angle moves it backward. a perfectly-upright seat tube would be 90º and would decrease in angle as the tube tilts backward). Seat tube angle is the angle of the seat tube relative to the horizontal plane, measured from behind the seat tube (e.g. Seat Tube Angle Seat Tube Angle What is Seat Tube Angle? ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |