Mountain Bike:


There is no fail proof way to perfectly size a cyclist to a mountain bike, however there are many factors that are universally accepted which can get you “on the paper”. It is important to work with someone who has experience in bike fitting, but is not so rigid in the data that they do not take your personal comfort into consideration. It is equally important, that you not be so rigid in your preconceived  idea of what is a proper fit to not try new things.

Reach and Bar Height

I believe that the reach is one of the most important aspects of finding the correct frame size for  mountain biking.  Try to find a frame with a  reach that will allow you to use a 50mm stem. I personally will not buy a frame that would require longer than 70mm stem and 35mm tends to be about as short as you can go. You will want a slight angle at the elbow when your are in your regular riding position,  Do not be in a hurry to cut your steerer tube, leave it long until you are 100% sure you have the height and reach of the bars correct. Use spacer above and below the stem and fine tune your bar height. You can cut the steerer down when you are done adjusting. Note: I recommend leaving the tube a little long and continuing to use 1 small spacer on the top of the stem under the cap. This makes a better interface between the stem and the steerer tube and can allow a small adjustment later on if needed.

Frame Size

Frame geometry varies wildly from different manufacturers. There are going to be some numbers like reach, that you have very little room for compromise, in other areas like seat tube length and BB height you may be a little more flexible.  Looking for off the shelf bikes will be often be challenging for a tall cyclist.  If you are going with a custom frame, there should be no need to compromise.

Saddle Position

The front of your forward knee should be over the ball of your foot, or slightly behind when the pedals are level in the horizontal position. Check this with a plumb line dropped from the indent under your kneecap. Move your seat forward or back on the rails to obtain the correct position. Your saddle should be basically level, and then adjust up to a couple degrees up or down for comfort. Check it with a level for a starting point. Note: you can make a shim out of wood to use to set the level in the future after maintenance or for different bikes.

Saddle Height

Your knee should have a slight bend in it when your foot is in the correct position and at the bottom of your pedal stroke.  Different people pedal differently IE heel up, heel neutral or heel down. It is best to check the angle when pedaling forward at a normal cadence as  your heel position can have an effect on the saddle height. Putting your heel on the pedal when it is in the full down position and setting the saddle to the highest point you can just slide onto with full leg extension will get you a starting height to adjust from.

Cleat Placement (where applicable)

Start by mounting  your cleats on your shoes so that the ball of your foot is directly over the pedal spindle and  the the cleats aim in a neutral direction. Pay attention to your pedaling and move your heels in and out to see if the float or release  is somewhat the same in both directions, adjust as needed.


Knowing what kind of riding you intend to do is going to help you decide what type of geometry you will need. There are lots of different styles of mountain biking, Cross country, all mountain, free ride, downhill, etc. I am personally not a fan of having  “one bike that does it all”.  If you have to do it all on one bike, pick the style that reflects what you will do most, the rest will be somewhat of a compromise.

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