But bums (and feet) are made for bearing weight. Hands are not. Furthermore, even excessively loaded hands don’t carry much of your total body weight. So halving the weight on the hands may only increase the weight on the bum by a trivial amount (5%?). That may not even be noticeable. It wasn’t in my case when I finally got some good advice from Colin Thomson, the man who designed the Spa Cycles frames with their notably slack seat tubes.
See his PDF and scroll down to saddle setback.This information seems to have been ‘lost’ at some point in the history of the bicycle. It was clearly understood at some point, because the diamond-frame bicycle had appropriate seat-tube angles for many decades. But now most people – including pro fitters! – think saddle setback is something to do with pedalling dynamics. It’s not, as recumbents should prove. Saddle setback is about weight distribution between saddle and handlebar. Too far forward, and there’s too much weight on the hands. Too far back, and you have to pull up excessively on the handlebars when riding hard.
The amount of times I ride behind someone with visible hand discomfort – seen from gestures like shaking their hands out every ten minutes – is kind of incredible. If you’re not a racer, why use a racing seat-tube angle? That guarantees discomfort because your cantilevered torso must be supported by the hands if the forward pedal is not far enough forward to hold up your torso from pedalling pressure (and,
automatically, core strength).
Put another way: even unlimited core strength – your core made of titanium – can not prevent your hands from bearing weight unless it has something to brace against. That all-important reaction comes from the forward (load-bearing) pedal. Obviously it has to be far enough forward, i.e. the saddle far enough back, that your pedalling force can bear your torso weight. The lower the pedalling force, the more forward must be the pedal. Long-distance riding involves low pedalling force.
A nice side-effect of getting the saddle back is that it suddenly becomes more comfortable to ride with a lower torso. Which is more aerodynamic. A lot of cyclists ride more upright than necessary because leaning forward throws weight onto their hands that is intolerable for more than a minute at a time.
Someone will claim a low torso needs an open hip angle, i.e. a steep seat-tube, but again it’s a question of proportion: a change of hip angle of one degree is nearly negligible whereas that same one degree causes a large difference in weight on the hands. It pays to optimise weight with the seat-tube angle.
Of course everyone who rides long distances thinks they’ve already figured out their position. Maybe they’ve even paid a pro fitter (who may not understand the basics above and probably thinks everyone should be set up for crit racing, i.e. high pedalling force).
Handlebar position, shape, tape thickness, glove padding, etc., are all beating about the bush. Get the weight off the hands and they won’t care about any of that. The
argumentum ad absurdum is riding no-hands for which you don’t need a handlebar at all.
Hand discomfort should not be seen as inevitable on long rides! And nerve damage is serious stuff. No way would I put up with that just because Specialized (or whomever) sold me a bicycle with an overly steep seat tube for the riding I do.