MTB Frame size question

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Hello All,

My girlfriend and myself are looking at buying a MTB each..Im looking at the Trek 8500 and her the Trek 8000.

My question is what would be the preferred frame size for us? I am 6'2'(189cm) and girlfriend is 5'8'....(173cm).

We have long been roadies so are confident riders...I know they recommend to have it on the smaller side rather than larger for MTB...I have tried the 19'5 frame and feels a bit tight...i feel much more comfortable on the 21'5....I guess it just comes to what the feels the best for the individual...any advice would be appreciated..

Cheers!!

Trying it for real and finding it comfortable is as good a sign as any, much better than whatever abstract numbers a calculator will give you..

Due to the riding position and highly sloping top tube of most mountain frames, frame size isn't as critical an issue as it is with traditional road bikes. If one size feels better than the others but still not quite 100%, you can always fine tune the geometry with stems, setback seatposts, saddle rail position etc. to dial it in 100%.

A mountain bike should feel a bit tight compared to a road bike. With a mountain bike you'll be off the saddle more, standing on the pedals. Your arms will have to absorb shock, and so the arms will be more straight. This puts you more upright. It's then necessary that the length between saddle and bars be shorter. So, the mountain bike should feel shorter.

A mountain bike should feel a bit tight compared to a road bike. With a mountain bike you'll be off the saddle more, standing on the pedals. Your arms will have to absorb shock, and so the arms will be more straight. This puts you more upright. It's then necessary that the length between saddle and bars be shorter. So, the mountain bike should feel shorter.
absolutely, mtb riding requires faster responses and you'll have to move the bike quicker when obstacles such as logs and rocks appear.

The frames have to be smaller to be more manoverable.

i would say:
6'2" - 21" frame
5'8" - 16" frame.

just a rough guide but you wont go far wrong with that.

Great!! Many thanks for all your advice....

I am 6'1" and got a Raleigh trail/entry level mountain bike for a rugged commuter. It's great for road riding just like I planned, but for Cook County's extremely tight, narrow, ravine-filled, root-filled forest preserve trails, it is a bit too large and feels awkward.

The top tube is 23.5" center-to-center. The seat tube is 22" center to top or 20" center to center. The fork angle looks relaxed, but I don't know what it is. The stem is longish.

You can't control the front end as easily over obstacles as a shorter bike and a steep ravine makes you want to jump off to protect yourself from the top tube, a situation which is definitely NOT helped by having to reach too far forward to steer.

A cramped upper body really takes the fun out but I never felt cramped on a 20" seat tube/22" top tube commuter bike with a stem about 1" long. (The solid fork left the front end lower). This was a used, one size fits all mass market machine.

If you don't give up some of the comfortable fit you are used to in favor of manouverability, why not just get some rugged cyclocross wheels for your road bike?

absolutely, mtb riding requires faster responses and you'll have to move the bike quicker when obstacles such as logs and rocks appear.

The frames have to be smaller to be more manoverable.

i would say:
6'2" - 21" frame
5'8" - 16" frame.

just a rough guide but you wont go far wrong with that.Sounds good to me.:)
I am 6'3" and I got a 21 and have no complaints.

Thanks for your reply.


Since I originally posted the question I did buy the Trek 8500 and my girlfriend the 6700 in size 21.5"' and 17.5'' frame size.

Cant speak highly enough of them..both are fantastic bikes!!!