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Want to buy a mountain bike. Sizing question.(13 posts)

Want to buy a mountain bike. Sizing question.Kristin
Dec 17, 2002 1:56 PM
Funny, you never hear anyone say that they own a road bike and decided to buy a mountain bike. Anyway, I just got my Christmas bonus and since i'tis the season to spend...

I've decided to buy a mountain bike to serve as my commuter. It makes sense, this way I have something that I can take off road and can ride it to the office. Am I correct to assume that MTB sizing is pretty generic and that a 19" inch in any brand should do? (A 19" is what fit me in hybrid frames.) If this is true, I can shop from the classified's fairly easily.
I would look at it same as road sizing...Souxsie
Dec 17, 2002 2:09 PM
Not all brands size the same way. Top tube length and angle vary quite a bit. Gary Fisher came out with that Genesis geometry a few years back and threw the whole thing out of whack.

While you may be able to preliminarily judge the size in a classified, riding it will be the best bet. But of course you knew that.

Good luck.
Not all things are created equalRickC5
Dec 17, 2002 2:15 PM
Mtn bikes are MUCH less generic and are subject to bigger differences than road bikes, IMHO.

First, if you intend to go off-road, you need more clearance between your crotch and the top tube than on a road/hybrid bike. Trust me on this, that extra clearance can be a big help in dismounting when the going gets rough and can mean the difference between getting off (gracefully)and falling over.

Second, stand-over height is what's important, not necessarily frame size, as a bottom bracket's distance from the ground can really vary on a mtn bike, meaning that one 19" frame may have noticeably more or less stand-over height than a 19" frame from a different manufacturer (or even a different model), depending on how far the bottom bracket is from the ground.

Third, you still have top tube/stem length to consider. Personally, I don't like to be as stretched out on my mtn bike as I do on my road bikes.

Lastly, the BEST commuting tire will NOT be the best off-road tire and vice-versa. Compromise tires are not real great for either purpose.

Have fun shopping! I wish we got holiday bonuses, but these days its good just to get a regular paycheck.
A little different than sizing a road bike. . .js5280
Dec 17, 2002 2:47 PM
Mt. bike frames tend to be sized smaller to allow more maneuverability. You want to ride more upright, with some bend in your arms and legs to help absorb the terrain. It also keeps your center of gravity a little lower and further back on the bike. There's more leeway though with mt. bikes on sizing. Aggressive riders (downhillers, free riders, etc.) will go generally with smaller frames for added maneuverability, while XC racers will go with larger frames for more efficiency, more akin to road sizing. Wrenchscience.com does a nice job of calculating theorical ideal sizes for both road and mountain based on your measurements. They tend toward an XC rider sizing in my experience. My guess is that's probably the type of you're talking about.

Mountain bikes are more diverse than road bikes, you have hard tails, soft tails, rigids, and dual suspension bikes, and that's just frame choices. My guess is your looking at a hard tail (front shock only) or perhaps a rigid. If you don't plan to ride technical trails, you might consider a cross-bike too.

The nice thing about mt. bikes is you tend to get more for your money. $500-1000 will get you a very capable, new, hard tail mt. bike. If you go used, it's important to make sure the shock(s) are in good shape, not leaking oil or air. They are expensive to replace. Also make sure the wheels and frame are not damaged or bent. People beat the crap out of mt. bikes (and themselves, see below) :-) Just as with a road bike, go out and ride a few, see what you like, and check out used options vs. a new bike. There's as many nuiances, if not more, to mt. biking as there is to road riding. It comes down to personal perference and the type of riding you're going to do. Lots of good stuff over at MTBR.com too and people who are willing to help.

It's always funny to see people stick to their first discipline. Mtb'ers ask road questions at MTBR all the time because they don't want to be intimidated by the Roadies (or they just think we're all a bunch of weenies)
re: Want to buy a mountain bike. Sizing question.JFST
Dec 17, 2002 3:06 PM
Mountain bike sizes tend to cover a larger range of body sizes compared to road bikes. You can even easily go with smaller frames than recomended as long as the top tube length is right and the seatpost is not past its minimum insertion limits and the steerer tube is properly spaced. You can get a very capable mountain bike for quite cheap but if you want high end stuff it tends to get considerably more expensive than road componentry.
MT Bike 3-4" smaller Than Road Bikeabicirider
Dec 17, 2002 3:12 PM
For me I ride a 50cm road bike or 19" C-T. Just finished buliding up a couple of MT bikes for me they are 14.5" C-C or about 16" C-T overall you will find the top tube is much longer on Mt bikes. I think a 19" MT bike would be border lined a Large frame 18"MED.

Good luck
Ray Still
Mooresville, NC
Ps your question abourt Northwave artics just gotta pair Road version they are 43.5 and they fit just like my Northwave evoultion Road shoes in 43.5 no difference.
echoing otherslaffeaux
Dec 17, 2002 3:39 PM
As others have said, there are many choices when it comes to moutain bikes. For commuting a hardtail bike will probably be a better choice. Full suspension is nice, but on the road and smooth trails it is only added expense and maintanance. Start looking at just over $500 for a good durable bike, and spend more if you want/can.

Sizing on MTBs is nothing like road bikes. I own several MTBs that vary in size from 17" to 21" and they all fit (in fact the 21" is a bit on the smallish side). The top tubes slope different amounts by manufacturer, and as a result the seat tube length varries. As a result the seat tube length is quite possibly the worst possible indication of size that could exist, yet it's still used. I much prefer to pick a bike that I need based on top tube length, but as another person stated, thanks to Gary Fisher, this no longer works either for all bikes. The XS-S-M-L-XL sizing is much better in my opinion, but that also varies by manufacturer - I'm a "large" in Santa Cruz sizing, and "medium" in Yeti's sizing at 6'0".

The good news is that sizing is less important on a MTB than on a road bike, as long as you are reasonably close in size most bikes can be made to fit you. Find a LBS with a large selection and try various sizes, and if you're a female try a few woman specific frames and see what you think. Being comfortable on the bike is the most important aspect fo the bike.
Ohhhh boy...fractured
Dec 18, 2002 12:22 AM
You just opened a very large can of worms...

Anyway (because I'm bored), I'll give you a run down on Mountain Bikes 101. I'm assuming here you're a complete newbie, so if not, bear with me.

First off, sizing for mountain bikes is NOT the same as road, cyclocross, hybrids, etc. I'm 6 foot 1, and for an XC hardtail, I would most likely ride a 19.5" frame, with a 100mm stem (I would take a 56 or 57cm road frame). Right now I ride a full suspension frame that would measure several inches smaller, to give me more manuverability in tight spaces and for jumping. I almost guarantee that a 19" will be too big for you. As is with road, it is better to run on the smaller side for mtb's than the larger side. A smaller frame allows more manuverability, and a more upright position for steep stuff. The only limiting factors are how much seatpost you have showing, and how stretched out for xc you want to be. I find that even for smooth trails I like my seat to be an inch or two lower than for road, and for the extreme stuff or dirt jumps, as low as it will go. Sizing isn't as critical with a mountain bike, as it is much more a personal preference. A large number of companies now offer only sizes S, M, L, etc... with the stem and seatpost making up the difference. Try before you buy. Beginners are usually better off with a more upright position and about a 100mm stem, plus a wideish low-rise bar. This will allow you to explore a few more areas of mountain biking than a hardcore xc rig will, such as freeriding, urban, maybe some jumps and steeps, and just general exploring.

Now I would really caution against shopping for a used ride unless you bring along a partner who knows about mountain bikes. In any case I HIGHLY recommend you visit shops and take some new bikes for test rides, to see what fits and what you like. If you're hell bent on a used ride, some steps you should take:

- Visit a shop and get fitted for a new bike. Record the importand measurements. This way when you shop used, you can compare the numbers to find a compatible fit. Sizing does vary between manufacturers.
- Make sure the bike you get has a 1 1/8 headtube. Modern suspension forks are not made in 1 inch. Even if you do not get suspension right away, you will someday

Because you want to commute on this bike, start with a hardtail (no rear suspension). They will be lighter, cheaper, and require less maintanance, plus the oft-overlooked benifit of teaching you bike handling skills. As for forks, I personally would rather have no suspension than bad suspension. Avoid elastomer forks, and get something with adjustable rebound. Stick with a fork from the big 3 - Rock Shox, Manitou, and Marzocchi. I personally would also avoid a fork more than 3 or 4 years old - the technology really is that much better. A (recent) air fork will give you more options, and will be a bit lighter than a coil sprung fork. Make sure your choice is oil damped.

You will probably end up on an aluminum frame, but steel is a possibility. There aren't many mass produced steel frames anymore though. I suggest Shimano Deore components or better, so you won't want to upgrade after a year.

On the subject of tires, you are looking at a big compromise when you try to do everything at once. Tire selection is very dependant on the terrain you plan to ride, so without knowing the conditions there I won't suggest anything. I would buy a tire to suit the dirt trails you plan to explore - yes you will be slower on the road, but you'll enjoy the trails far more. I recommend a 2.1 inch in front, and a 1.9-2.1 in the back. Your tire pressure should be higher for the commute, but lower on the dirt. Being a roadie, I'd expect you to tend towards rock hard ones - don't. I suggest a range of 30 - 50 psi for the dirt, depending on the tire. It will be more comfortable and grip much better. Run the lowest pressure you can where you don't get flats.

Wow, lots of good info. ThanksKristin
Dec 18, 2002 7:01 AM
That was a very informative post, and it will help a lot. I planned already to spend some time this weekend doing online research...but you all have helped me narrow the scope a bit. I am a complete newbie.

The reason I decided on a MTB instead of some other form of commuter (single speed or cross) is that the MTB can really serve two purposes. I can take it off road, on those occasions that people bug me to do so(or in case I ever get the itch on my own.) So I figure I'll just buy two sets of tires to begin with. For the commute, I'll run some smaller slicks and for off road, I'll get a set of nicer knobbies. It's all good. Thanks again.
Buy 2 sets of wheels?ColnagoFE
Dec 18, 2002 9:51 AM
You dont want to be swapping knobbies out everytime you wnt to go on the dirt. How long is your commute? Why not just go find some used beater at a thrift store to use as a commuter and keep the MTB for dedicated off-road use?
You must own a garageKristin
Dec 18, 2002 11:19 AM
For me, not so much real estate, if you get my meaning. Even the MTB is going to live in the bike room and will notta be so fancy.
For new, I would check out..rockbender
Dec 18, 2002 12:01 PM
the Marin 'Bear Mountain' I think it is called. My roomate (female) just got one not too long ago after we did quite a bit of research. It was in the 600 dollar range, has FULL deore components, and a nice steel frame. It also seems to be lighter than the AL framed Trek's, Giant's, etc. in the same price range.

Also, FWIW, my girlfriend has tried a few of the WSD frames and found that they did not fit her nearly as well as the standard frame sizes.

Ride a few and see what fits! Good luck and have fun!
Good luck, keep us posted. nm.fractured
Dec 19, 2002 12:58 AM