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· Banned
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I want to try my hand at MTB racing, but I need to get a MTB first. I just want a good fit. Before I head off to the LBS, can anyone tell me how road bikes correspond in sizing to MTBs? For example, I know that for a MTB, you are supposed to get a longer top tube than your road bike.

In general, how much longer is a MTB top tube supposed to be?
10cm longer?
20 cm longer?
30 cm longer?
 

· Power Napper
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barbedwire said:
I want to try my hand at MTB racing, but I need to get a MTB first.

LOL!!! If you have only been road biking, be prepared to eat a lot of trail dust and get your a$$ kicked. ;) I dont care how good a shape you think you are in.

There isn't an easy conversion. But start with stand over and go from there. In my experience shops will tend to set you up on mtn bike with a more upright position than a road cycist is used to. Be prepared to ask them to either lower the stem, or start by flipping it over to a flatter position. In general if you will be riding technical courses, err on a smaller frame size if you are deciding between two. It wil be easier to maneuver. If you are looking at longer endurance events larger may be ok. Also hardtail will feel different than FS and geometries tend to vary more greatly between manufacturers.

I am 5' 2" tall and ride a 50 cm (ct) classic road geometry frame. My mtn bikes are an 18" Kona hardtail that I love, and a Santa Cruz Juliana FS size small (women's). My Kona feels perfect. My Juliana I have only had about 6 mos. I am still working out set up as it feels big to me. Part of it is that the bottom bracket is higher than the Kona. Also the shop cut the head tube high and put in a bunch of spacers. I have lowered the stem, but will eventually have them cut the head tube down.
 

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a couple inches toptube clearance is good, with toptube length being quite important. roadbikes are in cm while mountain bikes are in inches of seat tube length. Now they are listed in frame size as small medium large,etc. because of various frame designs. Get fitted is the best answer.
 

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Competitive cyclist have a good fit calculator that can give you an idea before you walk into the shop.

http://www.competitivecyclist.com/za/CCM?PAGE=FIT_CALCULATOR_INTRO

You might be in for a rude shock in your first race, good mtbers are nothing if not fast.

Try and hook up with some local racers and get them to ride with you out on the dirt, you should learn a heap off them.
 

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More on the good mtb riders being fast, Cadel, trent lowe Ryder Hydel(sp?) etc were all pretty hand mtb rider before switching. And they have good dirt skills too.
 

· duh...
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slowdave said:
More on the good mtb riders being fast, Cadel, trent lowe Ryder Hydel(sp?) etc were all pretty hand mtb rider before switching. And they have good dirt skills too.


plenty of mtn bike racers train on the road... I think it's an easier transition to go from mtb to road than vice versa... dirt skills matter
 

· POGUE MAHONE
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slowdave said:
More on the good mtb riders being fast, Cadel, trent lowe Ryder Hydel(sp?) etc were all pretty hand mtb rider before switching. And they have good dirt skills too.

Dirt skills matter, however champion XC MTB ers do more training on the road than the dirt...hmmm wonder why?

as for size I ride a 58cm and a 19.5 and a 20 MTB.
 

· Large Suburban Male
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I've got the answer:

Go to a couple of LBS, tell them your cycling experience, and ask them to fit you to a Mountain Bike. Don't wing it.

The fit for one doesn't necessarily translate to the other.
 

· n00bsauce
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If you think road bike sizing can be confusing it can't hold a candle to mountain bike sizing. It's almost impossible to translate from road biking to mountain biking. Mountain bike manufacturers almost all size differently. IMHO, getting your cockpit length right is most important. If you do this then everything else will fall in line. You might fit an 18" in one manufacturers frame and a 21 in another and a large in the third. For short to moderate length races and especially with races run on singletrack I'd opt for a slightly smaller, quicker handling frame. If you plan on doing 24 hr. races or longer races on fire roads and ski/snowmobile trails I'd go with a slightly larger frame. There's also the hardtail versus full sus decision, kinda a personal preference but for a beginner it might be wise to choose a hardtail. It's simpler, weighs less and costs less. If you're a larger rider you might consider a 29er. You just can't assume the same size frame from different manufacturers will fit or even be close. Go to some LBS's and get a fit on several different bikes to get a hang for what sizes and manufacturers appeal to you. Also, try over at MTBR.com. They LUV newbies.
 

· Failboat Captian
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Ummmm, you might ant to start out by just doing some mountain biking. Other than the fact that you are pedaling two wheels, they are totally different sports. MTB racers train on road bikes simply as cross training for endurance. Stare up your first granny-gear climb (in a 22x32) and your whole world will come crashing down.

Yeah, go out and get a decent XC MTB, but don't start off thinking race, race, race. You need to learn dirt skills. Handling, climbing, rough terrain, downhills, single track, rocks, roots, leaves, mud, sand, hardpack, tire choice (way more important in dirt than road) etc., etc., etc. Plus, MTBing is much more anerobic. This doesn't even begin to cover how to handle the racing aspect. Just note that every MTB race is more like an ITT than the way you would envision it.

Don't expect that the first MTB you get will be a race machine. After a couple of years of riding in the dirt, you'll start to discover what style and size you want, how much rear travel (if any), what type of dirt riding you like, etc.

I'm more inclined to ride dirt than road, even though most of my riding is on the road. I entered exactly 1 MTB race and hated it. You can't deal with other riders the same way in the dirt as you can on the roads. If I were to enter another race in my lifetime, it'll be on the road.
 

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FatTireFred said:
plenty of mtn bike racers train on the road... I think it's an easier transition to go from mtb to road than vice versa... dirt skills matter
Indeed they do. You don't learn how to navigate the technical trails riding on the road. And they can really bite hard if you don't pay them respect.
 

· I ride in circles..
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You can fake dirt skills.. A slipping wheel is hard to control if you don't react correctly. If you are still at the point where you need to actually think about the skills to do them you're not ready to race on dirt. When you get to the point where crossing a 2 foot tall log, sliding on an off camber turn, and counter steering are natural reactions then you're ready. These skills are just a part of it too.. So many more to learn.

I'm not a pro and never will be.. but that’s my experience.
 

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Every time I try to 'fake' dirt skills, I end up eating same.Most mountain bikes come in only 13, 15, 17, 19 and 21. I'm 5"8" ride a 54cm road and a 17' mtb.
 

· Shirtcocker
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airs0ft3r said:
For me, I ride a 21" MTB and I would ride a 59 CM road bike. You should really get to a LBS and get fitted.
sounds like your MTB is really large...
 

· Shirtcocker
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Export A said:
Dirt skills matter, however champion XC MTB ers do more training on the road than the dirt...hmmm wonder why?

as for size I ride a 58cm and a 19.5 and a 20 MTB.
I'm 6'2" and have a XL (21-21" I think) Gary Fisher 26" MTB and a 19" Redline 29er SS. I ride a 62cm Colnago and a 60cm Bianchi. Rule of thumb for MTB is you generally want the smallest bike you can comfortably ride (though you don't want something where you are totally cramped due to short cockpit either)....smaller bikes work better on more technical stuff.
 

· The Dropped 1
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You can go out and race a mountain bike without a ton of dirt experience, but as mentioned, you will probably not do too well.

Even as a female I raced a few people that were training for the mountain biking portion of x-terra, or were roadies out trying a race, etc. I highly assumed they'd all be on it from the start and beat me up the road climb at our local venue, but right out of the gate I never saw them again.

Our local course is a LOT of singletrack, and some of it could be considered fairly tough for a beginner/mountain bike newbie just due to the steep climbs, a few rocks, hairy off camber turns. Piece of cake for a trail rider, but not someone that predominately rides on the road.

I've never done a road race, but I imagine similarly if I went out and expected to kick butt I'd have *plenty* to learn about road racing.

But, the only way you can get better is to do it! So, find some local trail rides and try to ride with better riders. Keep up where you can on the climbs and pick up as many skills as you can.

Many racers train also on the road because it's convenient and you can get in a lot of time/mileage without trying too hard. I spent nearly 4 hours pedaling on Saturday on my mtn bike and only got 23.8 miles. But it was all singletrack, and plenty of tech involved climbing and descending.

Can't simulate technical riding skills anywhere but on the trail!

As for sizing, definitely go to a local shop. They fit mountain and road pretty often, I'd imagine, so just explain what's going on and I'm sure they'll set you up!
 
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