Deducing MTB fit from road bike fit?

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jever98
Posts: 887
Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98

Hi,

I know my road bike fit coordinates, but not MTB ones and was wondering if there are ways to "translate" my road handlebar coordinates to MTB. Stack should be less of a question than reach, I guess.

Thanks for help.
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No longer in the industry

by Weenie


GlacialPace
Posts: 53
Joined: Mon Jul 30, 2018 12:37 am

by GlacialPace

In my experience it doesn't really translate. I seem to spend a lot less time on the flat on the MTB than my road bike and therefor tend to run the seat a bit further forward. Bars are much wider so seat to bar distance is completely out the window too. Saddle height is similar though.

Jugi
Posts: 445
Joined: Sun Jun 24, 2018 8:10 am

by Jugi

What kind of an MTB are we talking about? XC, DH or something in between. Road measurements may be applicable to a XC bike in some cases, but anything more downhill oriented plays with a different set of basic geometry.

jever98
Posts: 887
Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98

Good point. I'm thinking about XC. Would also be interested in flat bar commuter fit for my wife.
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GlacialPace
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Joined: Mon Jul 30, 2018 12:37 am

by GlacialPace

Yes, my comments were assuming XC, if its an Enduro or DH bike then even less relevant.

mattr
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Location: The Grim North.

by mattr

https://weightweenies.starbike.com/foru ... 1&t=153332

Jsut a matter of comparing things like saddle set back and height, crank length and then (if needed) rotating round the bottom bracket.

I haven't needed to until buying the current bike, and have had the same position (within measurement error/equipment availability)
Last edited by mattr on Tue Sep 18, 2018 9:38 am, edited 1 time in total.

jever98
Posts: 887
Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98

I'm not too worried about sale position, because I can fiddle with that. What I'm wondering about is reach, because that's so much more driven by the frame. On the one hand road bars are much narrower. On the other hand road bars tend not to be swept back and we tend to ride more on the hoods.

I observe that XC bikes tend took have much longer frames: eg the Canyon Lux in XL has a reach of 470mm, versus 390mm on my road bike.

Calculating with spacers and stem, the handlebar stem junction on the Lux is 5mm higher and 50mm longer in reach compared to my road bike (it comes with a 80mm stem).

My ultimate question is whether 50mm additional reach at the stem is too much, too little, or right?
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mattr
Posts: 4600
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

Depends on the reach of your road bars.

My position is set up to mimic the hands on hoods position, slightly closer as the bars are wider and slightly lower as i am (slightly) rotated round the bottom bracket.

jever98
Posts: 887
Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98

My road bars are compact, so about 80mm reach.

Hmmm, tough call.
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No longer in the industry

mattr
Posts: 4600
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

TBH if you get the torso/legs/crank stuff right. Hands and arms are easy to fix, just buy a new stem.

Hell, I've got stems in half a dozen lengths and rises to experiment with anyway. Wouldn't use many of them long term, but for fit purposes they are ideal.
(I have a lux as well)

jever98
Posts: 887
Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98

I think about it the opposite way: the crank / saddle part is pretty easy to fix - basically a matter of seat post and set back.

The reach equation is the complicated one in my book, as you don't want to use a super short or long stem. E.g., if the Lux was too long with me with a 80mm stem, I can't just use a 20mm stem. Same on road bikes - sweet spot for riding is somewhere around 110-120mm, I would never ride a road frame with a stem of <110mm - rather choose a shorter frame.
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by Weenie


mattr
Posts: 4600
Joined: Fri May 25, 2007 6:43 pm
Location: The Grim North.

by mattr

Which is one reason (of several) why I'm higher and less set back on the lux than my last bike (which duplicated my road position pretty accurately).
Seat tube is steeper, reach is longer, front centre and weight distribution is different. Ended up with a 90 stem, when combined with the bigger sweep of the bars I've choosen gives me the equivalent of a ~70 stem.

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