I've been primarily a road cyclist ... but I live in an excellent location for mountain biking also, and I want to get started.

My questions are regarding fit. Will my road bike measurements translate directly to a mountain bike? I assume saddle height and setback from BB should be nearly identical? Reach and stack is where I'm really not sure. Since MTB handlebars don't have the "reach" of road handlebars, is there a way that people swag this measurement? It seems like you could measure from nose of saddle to "hoods" on your roadbike ... and come up with a close distance for flat mountain bike bars.

Also, is there any reason I can't use my favorite road bike saddle on a mountain bike? I run a Selle Italia SLR Superflow 145. The only downside is I might get a mud splash right on the center of my rear, in the cut-out?

Scott

The main difference is that MTB frame toptubes are about 50-70mm longer, whereas on a road bike, the drop bars add additional reach to the toptube and stem. MTB riders tend to run a shorter stem and more upright postion too for better control at lower speeds and the need to get low'n'aero is less important. Choice of saddle is down to rider preference, but MTB saddles tend to take more of a beating - particularly on a hardtail, as well as coping with the occassional 'off'

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Just ride

For me, the relationship between my seat and the center of the bottom bracket is exactly the same. On road bikes, I am very flexible and generally run 110 stem with zero slope and no spacers or one very small one. On comparable size MTB, I generally run 80-100 stem with around 15 mm spacers under and a stem with slight upward slope. Also, the seats that I like on road bikes, I hate on MTB. Most MTB seats have flatter fatter rear section since you sit more back on your sit bones.

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For certain parts stiffer is more important than lighter.

My overall reach on my XC Race bike is 40mm shorter than my road bike. Which is fairly typical to what I have seen with others. Mountain bike fit in a more rec or all mountain style is much shorter and more up right and a lot to personal choice. I don't seem may Pro XC bike with high front higher than the seat.

Oh yea, the other part of fit-drop. My road bikes the bars are way below the seat (I am very limber) and on my MTB the bars are almost up to seat level, just slightly below. You are just going to have to buy a mountain bike, set the BB to seat distance from your road bike and experiment with all the other perameters including the front-rear orientation of the seat with respect to the BB. The distance BB to seat will be the one constant.

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For certain parts stiffer is more important than lighter.

I run a pretty similar position as my road bike. I use a 110mm -17 degree stem sitting on the top cap. For my it feels soo much better to be stretched out and having my handlebars a bit lower. I can't stand a short stem/wide bars combo

Thank you for the feedback, everyone. Good to know saddle height and setback are similar. I'll have to play around with stack and reach.

Scott

I am in a similar road/MTB community. I run exactly the same position as my road/'cross bikes (in fact, I am running drop bars on my MTB, too).