Just a quick question. I think I heard somewhere that it is a good idea to get a slightly smaller MTB frame than a road bike frame. I know, I know...fit is everything. But is this advice true?

Don't know about if one should get a smaller frame. However due to their design, the measurements are different for a MTB as compared to a road bike. Usually you will fit a mountain bike whose frame measurements are 9-11cm less than your road bike.

So if you ride a 58cm road bike, you will likely best fit a 47-48cm (or 19") mountain bike.

Same is true for a hybrid bike. I usually ride 17"-17.5" hybrids, which is 43-44cm. But I fit a 52-54cm road bike.

Main thing about a Mountain bike is top tube clearance. At least 4" clearance between the crotch and the top tube is the suggested but That is only important if You are a rider that will suddenly jump off the saddle and put both feet on the ground. I normally hit the ground by falling off and as the bike is horizontal - or vertical inverted when that happens- It doesn' t bother me too much.

Colour doesn't matter on a mountain bike as it soon finishes up as mud tinted.

Sizing-I ride a 40cm compact mountain bike and a 51 road bike- or 46.5 if it is compact frame- But there are so many variables on set up with long seat posts- riser bars and bar ends- It is not critical. Just get more than 2" clearance and you will be fine.

DG like with road bikes it's not that easy but mountain bike sizing is generally but not always as it depend on your reach as well. You got to be able to reach the brakes comfortably while pulled off the back of the bike...

so 5'2" - 5'6" small (14-15)

5'6" - 5'10" Medium (16 - 18)

5'10" to 6' large (18-19)

6' - 6'3" Xlarge (19 - 21)

and over 6'3" whatever you can get.

And of course there is alot of lap over.

I had two medium bikes. The first was the Specialized FSR Stumpjumer. The second is my current Santa Cruz Superlight. Both are 17" (I'm 5'8"). The FSR was a huge bike compared to my Superlight because of the head tube angle, fork (5" vs. 4") and reach. My Santa Cruz is actually a little too small. I apparently am a "inbetweener". This should give you some indication what to look for.

Thanks, this is helpful. I'm 5'10" tall, and wear pants with a 30" inseam. (Waist has gone done from 44 ugh to 40 and closing in on 38 woohoo).

Looks like I should be looking at Medium or Large. This is helpful when I can get the size from the Craigslist crowd, so I won't waste my time looking too small or too big. I can at least check the mediums or larges with a good chance they will work.

You are unfortunately at a "tweener" size so suggestion is go to some shops (like you probably have already done) and test ride some bikes. Sizing will change between style of bike (ie cross country vs. all mountain), size of fork (3, 4 v 5, 6 ") and just generally bike construction. At 5'10" I would think a large, 18.5" would be just right but you never know. I have a bud who is 5'10" who rides a large SC Blur and the bike is really too big for him. He's OK on regular flat trail but down hills, he has trouble reaching off the back of the saddle.

Bottom line it's what feels comfortable for you. Do you have any friends with MTB bikes you can borrow and ride? Really need to get out on a trail to know if the bike will work. Or you can do what I did, bought 4 bikes until I found the right one. Isn't that what we all do?

This is really timely information. I'm watching a medium Santa Cruz Juliana on eBay, and the seller says he thinks it would be too small for me (I'm 5'7") based on how it fit his wife. Your experience seems consistent with that. So I guess I won't try to win the auction. Thanks for saving me money!

Unless the bike has an extreme compact top tube, a large may well be too big for you. At nearly 6 feet with a 31 inseam I ride an 18 (see note later) and have often thought about a 17.

Note: MTB manufacturers have much more variation between virtual top tube length than road bike manufacturers do (Possibly because road bike design is more mature). Even though I ride an 18" MTB, the top tube is in excess of 23" long (virtual). Haro builds their hardtails like that with an extremely sloped top tube which provides the clearance the Stapfam points out is "comfortable". In addition to all of this is suspension sag. If the front fork sags the recomended 25% of travel when your weight is on the bike then the top tube will be at a much higher level when you climb on the bike or stop suddenly than it will be when riding.

Most recomendations are to go with the smaller size when in doubt. You will be more able to hang the but off the back of the saddle to better distribute the weight during technical descents. You will ride level ground with your arms more bent (No straight arm riding) and the bike will be more maneuverable on tight twisty trails.

I am 5'10" with longish legs and have a medium-sized Specialized Stumpjumper FSR Elite (2007). I think a large might be too large for you. I recommend the SJ as a good bike.

Get a medium. Better for a mtb to be a bit small than a bit large. I'm 5'8" with a 29" inseam and I prefer a small.

I'll join the chorus in recommending a medium. I am 6' even with 34" cycling inseam (32" pants). I ride a 57.5cm road bike. I ride a 19" (L) MTB. The L fits me fine. It would be easier for me to fit a M than a XL.

Unless I'm building an ark this weekend (a distinct possibility), I'm going to check out a Trek 820 which happens to be a medium. Price is right -- $100, if the bike's in good condition.

The Juliana is a women's specific bike which means the top tube is ever shorter than the Superlight top tube. I thought about getting a Juliana but it would have been really too small for me. It depends on your body. If you have long legs, shorter arms it may work for you. Other thing to remmeber and why I got the Superlight instead, is the fork is smaller, not as heavy duty as the fork on the Superlight. Basically one is meant for guys and the other smaller, lighter women. If your weight is around 100 - 140 it would be OK.

Ha! I almost spit all over my keyboard on that one!

The Juliana is definitely not the right bike for me.