What's my MTB size?

[phcollard]

Hey guys!

I'm thinking about building a mountain bike one of these days. I am not actively hunting but I want to be ready when a nice frame shows up in the classifieds.

Thing is I am totally ignorant when it comes to MTB sizing (last MTB that I rode was a cheap Kona Fire Mountain 10 years ago and I don't even know which size it was). So I'm 5'9 with a 83cm inseam. I ride road bikes that have a 55 to 56cm top tube if it helps... A friend told me a 17" or a 18" MTB would fit me but I don't even know what it means LOL. Oh and would size change between a 26er and a 29er?

Thanks a lot for your wisdom! :)

Philippe.

[christian]

On any stock MTB, you're a M(edium) or 17".

[phcollard]

Thanks a lot Christian!

[gdw]

You should be looking for mediums or 17-18" frames with top tubes from 22.5-23" if the they use 26" tires and 23-24" top tubes for 29ers.
Do a few demo rides before buying to get a feel for how the different frame and wheel sizes handle.

[dustyrider]

I'd agree with the advice already given and stress the demo time!
A lot of shops offer full day demos for a small price.
There are so many variances across manufacturers it's worth narrowing it down with a few parking lot spins, and then a day on the local trail with the bike that seems to fit you, and your price point.

[Jack Brunk]

In some cases you may be better on a small 29er if your looking at full suspension 29ers. Look at the TT length as your number one measurement. Some brands run longer TT's than others. Best advice is to test drive every model that you can.

[phcollard]

Thank you so much folks. You were very helpful! :beer:

[deechee]

I'm slightly shorter but have a longer inseam, and ride a Giant XTC size medium now. My previous NRS dual suspension in Medium was a bit long on the top tube. That said, I've ridden sizes from 16" to 19" comfortably. The main reason for a shorter seattube/top tube clearance is when you fall, or when you get stopped on the trail and your rear wheel is higher than your front. Trust me, that 16" frame saved me a number of times when I used to go to Bromont regularly.

The measurement in inches is a reference to the seatpost length.

Renting bikes in Bromont (http://www.skibromont.com/velo/fr/velo.location-velo.htm)is expensive but at least you'll get to try the bikes on real terrain.

Even if you still had your old Kona, I find current mountain bike geometries have changed significantly from 10 years ago. Seat tube angles are more slack, and body weight is farther set back.