XC Cockpit Formula?

Saddle first and foremost at sag levels

Then bar position based upon many miles experience with climbing and adjusting stack for what Rides best and give me leverage.

Poor saddle position is recipe for disaster (pain, injuries, cramping deep in races.) adjusting my saddle position up and forward over time pretty much eliminated my adductor cramp issues.

I can also deal with many different reach feels, but if sweep is off it causes immediate issues with hand pain, numbness and overall feel.


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I am working on my saddle math right now. I am using two techniques the Heel on Pedal technique and the 109 technique and am getting 6cm difference... ugh! I really want to order my bars and stem on Monday, so am trying to figure this all out this weekend. I have a set of 680mm and 780mm bars to test and a 110mm and 60mm stems to experiment with... I am guessing I will end up with 740mm bars and a 40mm-90mm stem. The bike is an XL Epic Comp and I am really inbetween a L and an XL so my stem will most likely be shorter than most XC stems. I am accustomed to 780 bars on my trail bike and love that width so can't imagine going sub 700mm on bars, but know the wider bars will pull me forward. I just do not know of a "proper" formula for figuring out REACH. Any thoughts on that?

I start with the saddle too. I can make cockpit adjustments afterwards when I get a few miles in if that's necessary. I cannot manage if my saddle is too high, too low, too far back, or forward. Those lead to injury.

I have never really been a big fan of saddle height formulas. They might put you in the ballpark but that is it.

I find the best way it to pay attention to how you are seated on the saddle. If you find that you are creeping forward on the saddle then it is probably too high. If you are pushing yourself backwards on the saddle then it is probably too low. The "right" seat height will have you comfortably centred on the saddle.

As for your stem and bars. On that bike your likely sweet spot is going to be 60-80mm stem with a 700-740 bar.

Start with saddle -> optimize for sitting position. It's clearly the way to go for road and TT.
Start with handlebar -> optimize for standing position, or when dropper post is down. It's clearly the way to go for BMX and trickbikes.

MTB: well, which side its closer to? BMX or Road riding?
For XC, it's clearly need to optimize for seated pedaling so seat first.
For other types of MTB where you mostly move around and not just sit and pedal, you may start with handlebar position first.

LMN said:

As for your stem and bars. On that bike your likely sweet spot is going to be 60-80mm stem with a 700-740 bar.

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I'd make it 40-70mm effective stem length. Effective, as in deducting the backsweep of the bar from stem length first.
My 70mm stem + my 16 degree backsweep bar has effective stem length of 40mm if I were to use bar with little to no backsweep.

Do yourself a favor and get a professional fitting.
They'll fit your bike to your body and you'll learn a lot too.
Worth every dollar IMPO.

If you want quick way to set your starting point:
Watch this video

Then after you get some idea, read around about RAD and RAAD.
Bewarned, disregard the height-based formula. Just measure your optimal RAD off the bike. Then set your bike at that RAD as a starting point.
STARTING POINT though. I eventually prefer slight RAD+ (slightly longer than RAD) setup.

Heel on pedal is actually pretty close for me, usually a bit lower as I set it so it's comfortable spinning at up to 150rpm.

So that's what RAD is.
I call it my "BB to Bars" measurement (about 40mm longer than his formula).
I like to get it and my "Reach to Bars" similar between bikes.

When I ride my 2011 Kona Unit, I get that "perfect fit" feeling and try to replicate it on the others.

Yeah, glad this makes it much clearer. Definitely don't go by a formula, measure it for yourself, with your bike and then you'll know it's right. However going under is better than over, I think a lot of XC racers get that wrong, myself included previously.

I still couldn't ride exact RAD though.
RAD+2cm has been my most comfortable position. RAD+1cm adds more weight/numb feeling on my hands because my natural position wants to push the bar away from me just a bit. Exact RAD put the bar too close to me that I can't even ride over 2 hours.
I currently ride RAD+1cm. It's close enough to RAD. But tolerable.

I start with reach so my knees don't hit the fork crown when standing climbing.
Then a seat to grip drop of 10-30mm and a stem that will get the BB-Bar (RAD) around 840mm.
Seat tip about 60-80mm behind the BB.

None of my bikes have all of them, but 2 out of 3 isn't bad.

RAD-minus definitely can have a conflict with the knees, but RAD-0 and under has a definitely positive effect on handling, especially when you have a significant saddle-bar drop.

Hexsense said:

I still couldn't ride exact RAD though.
RAD+2cm has been my most comfortable position. RAD+1cm adds more weight/numb feeling on my hands because my natural position wants to push the bar away from me just a bit. Exact RAD put the bar too close to me that I can't even ride over 2 hours.
I currently ride RAD+1cm. It's close enough to RAD. But tolerable.

Click to expand...

On my Enduro bike I am pretty darn close to exact RAD. But like you I find it very uncomfortable for extended pedalling, particularly if I am pedalling with a kind of urgency.

To me RAD is just another example of that compromise game we play in mountain biking, descending performance versus pedalling performance.