Road Bike, Cycling Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
8,116 Posts
Discussion Starter · #1 ·
I am posting this in here in road because I am looking for a direct comparison to road bike sizes.



Anyway, I ride a 57 Look- which is slightly larger than a 58 Trek. Any ideas why size mtn bike this translates to? 19? 21?
 

·
gazing from the shadows
Joined
·
27,387 Posts
filtersweep said:
Anyway, I ride a 57 Look- which is slightly larger than a 58 Trek. Any ideas why size mtn bike this translates to? 19? 21?
Sloping top tubes. VERY sloping top tubes in some cases. Some MTBs measure c-c (because crotch clearance is pretty important on the trail), but even if they measure c-t the seat tube is still probably shorter than on a road bike because of the slope. That's probably why the numbers on frame sizes compare the way they do.

Go by top tube length. If you know how you want to set up your MTB that is. Many people like a shorter TT on the trail and a more upright position. For a dually I would go that way, not so much for a HT, but that is just me. Effective TT is the measure you want for sizing MTBs. Clearance (and ST measure) is really not much of an issue with most designs unless you have short legs (like me).
 

·
Banned
Joined
·
657 Posts
Filtersweep:
If you ride a 58+cm Trek that translates to about 23in road size. I ride a 47cm (18.5in) rd & 14 in mtn – about a 4.5in difference for me. If I were you I would go w/ the 19in mtn – lots of stand over clearance for trail & a nice tight compartment for good maneuver ability.
 

·
Registered
Joined
·
8,000 Posts
I ride a 54cm tradtion roadie and a MED (49cm) Compact frame.

On the MTB side I ride either a 16.5" with a 57.4mm TT currently and my KLEIN was a 15.7" with a 55.1cm TT.

I use the stem length to adjust fit.

As I long time MTBer I would say go for standover first over TT length.
You will wnat this on the MTB side to geive the boys some room when you jump off. I like to have claose to 2-3" of room if the trails are tight and techincal. If they are faster and smoother a slighty larger frame is fine.

IMO the worst thing on a MTB is not to have stand over clearance if you bail out!

Are you looking at a HT or FS? Smooth trails or technical?

I would say between 18 -19.5" frame will do well. Then look for the TT you want and adjust with stem length.
I prefer a longer TT and shorter stem on the road, but a shorter TT and longer stem on the MTB.
 

·
Registered
Joined
·
8,116 Posts
Discussion Starter · #6 ·
I am looking for a hardtail that can handle both technical and smooth trails. I had the misfortune of finding a Bianchi that had everything I wanted, but was only in a 21" (although it was Bianchi's screwy sizing). It was discounted by 2000nok- (last year's model). I guess I will keep searching.

DIRT BOY said:
I ride a 54cm tradtion roadie and a MED (49cm) Compact frame.

On the MTB side I ride either a 16.5" with a 57.4mm TT currently and my KLEIN was a 15.7" with a 55.1cm TT.

I use the stem length to adjust fit.

As I long time MTBer I would say go for standover first over TT length.
You will wnat this on the MTB side to geive the boys some room when you jump off. I like to have claose to 2-3" of room if the trails are tight and techincal. If they are faster and smoother a slighty larger frame is fine.

IMO the worst thing on a MTB is not to have stand over clearance if you bail out!

Are you looking at a HT or FS? Smooth trails or technical?

I would say between 18 -19.5" frame will do well. Then look for the TT you want and adjust with stem length.
I prefer a longer TT and shorter stem on the road, but a shorter TT and longer stem on the MTB.
 

·
Registered
Joined
·
80 Posts
On a mountain bike standover clearance is key. Stand over the bike's top tube about 6 inches in front of the point of saddle. Then lift the bike by the handlebar until the top tube touches your crotch. Check to see how much of the front wheel was lifted off from the ground. You would ideally like to have 2 inches minimum, but you can go down to 1 inch. But if you have less than 1 inch, then move down to the next frame size.

The effective top tube is not as critical as in road bikes. Most frames will be in the range, and adjustment can be made with stem length. Frame manufacturers make their bikes with some specific geometry to differentiate their bikes. For example, Gary Fisher is known for their Genesis Geometry which tends to have much longer ETT. Also by riding a mtn bike, you will be constantly changing the riding position, i.e. move up a little to climb, move back while descending.

Hope this helps.
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top