Posted by: fartymarty
Kenny - I currently have a HT that has a 75mm shorter reach than my FS bike. Both have a similar "butt to bar" measurement but are very different in geometry (old school HT and new school FS). I like riding both as they are very different in terms of handling. I can generally ride the same trails on both - maybe with the exception of super steep / tech trails which i'm not going near on the HT. The HT is definitely too short at 440mm and the FS could be* considered too long at 515. * depending on who you ask.
As such the things I can control are the contact points and set up of bars / stem etc. I think I am with Joseph on this one - that you can adapt - but it's still very much a "work in progress" and I don't think there are any right / wrong answers. It's just nice to get some others opinions on it.
Blofeld - It is a bit of a minefield that isn't talked about. I also agree stem length should be measured parallel to the stem, not horizontal.
Similar butt to bar is one thing. But I am more with Vic, the fore/aft seat position relative to the pedals matters for pedalling efficiency/comfort as well. So on different bikes, you're going to compromise one for the other, unless you're willing to allow your bar/steering axis relationship diverge.
What it comes down to is you have a few competing metrics here, optimizing one comes at the expense of another. In theory the closer a frames geometry is to fitting you for the desired purpose, the closer you can get on all metrics without compromising:
- Optimal fore/aft saddle position relative to pedals.
- Optimal butt to bar.
- Optimal pedal to bar (RAD, as Lee likes bikes would call it)
- Optimal grip center to steering axis center.
- Optimal grip center to front axle center (not mentioned here, but relationship of hands to axle is as relevant as anything, arguably).
Optimising one at the expense of other with likely improve one aspect of bike handling and hurt another. Different peoples mental and physiological makeups, and riding styles, impact which aspects they benefit most from having optimized, and which aspects they can best compensate for of they are less than "perfect".
To me, the comments that steering feel is the main determining factor in "bike handling" is for me just not the case. On a road bike or on mellow terrain where your cg stays pretty static other than leaning over, I could see it being a dominant factor, but just personally I care about range of motion, leverage, and weight distribution when riding on a mountainside, and I would not compromise those things for anything, really.
I do agree that whatever dimensions you decide to compromise on, you can adapt. But I will say another word for adapt in this context is "compensate".
When at mach chicken with eyes watering and heart pounding, when I am standing in a neutral position on the bike I want to feel totally balanced and like everything is weighted properly just naturally, I can shift forward and load up the front wheel or shift back and loft the front wheel with equal ease and zero real conscious effort.
For me that comes down to "perfect" RAD/RAAD, not necessarily in the formulaic sense lee prescribes, but as determined by iterative testing.