How to Setting stack height stem length rule of thumb

[defy1]

I am experimenting alot with stack height and stem length on my MTB currently, and essentially want the best all around neutral setup for both climbing and descending. In road bikes, the rule of thump setting up the stack height and stem length, is that when on the hoods, you look down towards the front wheel hub it should be roughly covered by the handlebar.
Can this rule of thumb be also applied to mtb?

 

[pineapplehead]

No. There are too many variable factors to consider. Such things as head angle, bar offset, and fork length will affect where the hub is positioned in relation to the bar.

 

[safreek]

Unfortunately or fortunately, depends on whether you like fucking around with bikes, you have a fun job ahead. I know fuckall about bikes but continue to pull them apart to make them perfect for what I want to do, then I change what I want to do.
Nothing will ever be perfect even when it is

 

[mtb101]

you want 4 key ride positions (I'm thinking xc), 1 descending (better not be too far over front wheel - i.e too aero or you otb), 2, climbing (not too far back of course as want front wheel not floating, rear still has weight for bite - so seated can you climb?), 3 attack (off seat, mid bike so even distribution of weight on wheels - you're floating in centre of bike - like a giant pendulum you can flick bike where you want, so you have master control based on this positon), 4 neutral seated (position that allows you to ride comfortably for 2-3 hours - and make good power, no lower back, no numb hands) - this is roadie position.

how to set up; get it ball park at home then bike fit happens on the trail, go out with your tools and find some good sections, position is about compromise between the 4 above, stem will be shorter than longer, seat to bar drop will be conservative, seat for/aft seated power a priority here, bar width (650-750?), priority would be position 3, then 2 - 1 and 4.

 

[defy1]

Thanks for the replies.
But when setting initial baseline setup, it would be done in position 4 right? Not really whilst in position 1,2,3 ,

 

[pink poodle]

Biggest issue I can see is running roadie hoods on a mountain bike.

 

[schred]

Short answer is I don't think so, as you'd know stack height is technically related to the frame and determined by the size selected (in this case afait accompli) and stem length a function of reach, preferred bar width and personal preference (and budget to keep trying new bar/stem combos). I guess you mean stem height, and whereas on a roadie the top of the bar and hoods are almost the highest part, on an mtb that's more likely to be at the grips, effectively your handlebar height. TBH I haven't thought about it before but I just don't think it's that precise on an mtb compared to a roadie, maybe also due to more available permutations of tyre size and pressures/fork AC lengths/susp sag/headtube length combinations that (not withstanding your handlebar type - flat/low rise/high rise) all dynamically affect front tyre ground to axle distances which change your effective h/bar height. I guess a rule of thumb could exist in there somewhere, but not sure how.

Also see posts above, it also depends on whatever your riding preference, your bike, your fitness level & what you can tolerate/aspire to, terrain, riding priority etc is. So IMO it's not that precise, it can't be, and should be arrived at differently for everybody even if it ends up the same. And as safreek pointed out, it changes as you change as a rider, so don't expect to nail it first go. If you are willing to post a bit of background about yourself, your ride and riding types then I'm sure people can chime in with what they might expect to see you running.

 

[born-again-biker]

Like the OP, I experiment with this stuff quite a bit but haven’t quite nailed it yet.
My frame is a little short on reach & stack for me ‘coz I am 6’3 & have ridiculously long arms.
I am about to order some 38mm riser bars to continue the experiment because the position I feel least comfortable in is standing attack.
As others have said, it’s a big experiment for each individual. I try to be a bit ‘sciency’ about it & take mental notes of each change.
Sometimes when I order parts I chuck in a few diff. spacers to add to the toolbox.
If there is a well worn ‘rule of thumb’ I’d love to know....




Sent from my iPhone using Tapatalk

 

[mtb101]

Thanks for the replies.
But when setting initial baseline setup, it would be done in position 4 right? Not really whilst in position 1,2,3 ,

yes 4, don't worry if you feel a bit upright, you can drop it once you've done a few rides.