Big guys on bikes
As the specialist in bicycles for tall people, I wonder if you have any thoughts about how to tame an unruly front end on a 64cm frame?
I am 6 foot 4 and ride a Colnago Master Olympic with a straight steel fork, an ITM Goccia quill. The quill diameter is 22.2mm, length is 120mm with 76 deg rise. When climbing, I like to sit up and ride with my hands on the tops of the bars. When I do, the front end gets squirrelly, as if the bike wants to pull a wheelie. No problems when I am riding on the hooks or in the drops.
I've tried riding with my hands spread wide apart, but the front end still feels "light." What can I do to address this problem?
Tall bikes under tall riders have a tendency to feel light on the front end, especially if the top tube is too short. It is a weight distribution problem, and I can explain why it happens more to taller riders. In general, road frames from a given company tend to have the same chainstay length for all sizes of a given model. Furthermore, the seat tube on the bigger frames is not only longer, but it is usually also tilted back at a shallower angle.
This means that your butt is higher and further back over the rear wheel, effectively placing your center of gravity further back relative to the wheels than a shorter rider. Combine this with insufficient reach to the bars for the taller rider relative to the shorter one, and you have a bike that will pull wheelies when you climb holding onto the bar tops.
With this bike, I suggest deeply bending your elbows and lowering your chest when climbing to put more weight on the bars. It's not ideal to be forced to do this, but you actually will work your glutes more as a benefit.
You might also try the free frame fit calculator on my Web site: www.zinncycles.com
, to see if you have a relatively short top tube and stem, in which case you could increase your stem length and help it a bit.
Lowering your stem will also help, but that may not be ideal, since tall riders on stock frames generally have relatively more drop to the bars from the saddle than shorter riders.