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· In FTF We Trust
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I don't know that there's much correlation between road bike tt length and mountain bike tt length. My road bikes have 55-56mm tt lengths and my mountain bikes have 23.5-24" tt lengths. The road bike have to be sized smaller due to your body position on the bikes.
 

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drop bars extend your reach

dr.dirt said:
Whats the dealeo with niner top tube lengths? If my road bike has a 59cm TT I figured it would be pretty close but the XL has a 64cm. Ehhh?
Because drop bars extend your reach, you will generally need a bit longer top tube on any bike that is flat or riser bar equiped.
 

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Why so much longer

Sorry to revive an old thread but I am still struggling with this...
I'm 5"11 with 32" inseam
I saw a GT Peace 9r size SMALL in the shop saturday and the salesman told me: "too small for you". I tried it and:
1. Yes it is too small but the stem is only 60mm !!! Top tube is 590mm (23.2") I used to ride my 26" with 575mm TT but 120mm stem (same for my road bike).
2. I wear 11 shoes but did not have toe overlap

Since it is the last model in stock, I am still keen on getting it.

What is the risk of riding with a 120mm stem a frame slightly too small?

I have the feeling that it should be more agile in switchbacks.
Is there a real risk to fall over the bar more often on steep drops ?
What other issues do you foresee ?

I still don't get it why 29er have such long TT ?

Advice appreciated.

PS: I'm also insisting because this bike has disc brakes (dunno why) and the Medium size I can get from another LBS is V-brakes only.
 

· Keep on Rockin...
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6,674 Posts
Well...

eric_syd said:
Sorry to revive an old thread but I am still struggling with this...
I'm 5"11 with 32" inseam
I saw a GT Peace 9r size SMALL in the shop saturday and the salesman told me: "too small for you". I tried it and:
1. Yes it is too small but the stem is only 60mm !!! Top tube is 590mm (23.2") I used to ride my 26" with 575mm TT but 120mm stem (same for my road bike).
2. I wear 11 shoes but did not have toe overlap

Since it is the last model in stock, I am still keen on getting it.

What is the risk of riding with a 120mm stem a frame slightly too small?

I have the feeling that it should be more agile in switchbacks.
Is there a real risk to fall over the bar more often on steep drops ?
What other issues do you foresee ?

I still don't get it why 29er have such long TT ?

Advice appreciated.

PS: I'm also insisting because this bike has disc brakes (dunno why) and the Medium size I can get from another LBS is V-brakes only.
There seem to be two schools on 29er effective TT length (the way I see it). You are right in that many 29ers go with a relatively long TT and expect you to use a short stem. I suppose this is for a few reasons. These include, but are not likely limited to, needing a relatively longer TT to prevent toe overlap on smaller sizes. And, maybe to dial in front end handling but a lot of that has to do with HA and fork rake manipulation.

The other school seems to like keeping the tt close to that on a 26" rig and going with a longer stem. Personally I much prefer the effect a longer stem has on steering. Shorter stems make front end handling seem choppy and over-reactive, especially on the low speed trails. But that's just me, others will surly disagree. To add more to the mix I prefer a 29er with a HA closer to 71 degrees and a bit more rake on the fork. But that's a different matter.

Now to answer your other questions about the drawbacks of longer stems. If the HA is relatively steep, the forks rake is short, and you have a short TT... yes you will be far more endo prone and downhills will feel a bit scary. On smooth windy single track you'd be able to more easily rail the turns at higher speeds. More weight on the front end sticks the front tire and is great for sharp high speed turns but not so good when the trail points downhill.
 

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Figure roughly two inches longer than your road bike.
You don't fit a MTB like a road bike. If you did it would be an over the bars machine.
My MTB's top tube is 1.75" longer than my road bike. But it's stem is 1" shorter.
When I first started MTBing I scoffed at guys who's seats were lower than their handlebars.
My seat was higher than my handlebar as on my road bike. I would outclimb most of them on the fire road but it would be them waiting for me at the bottom of the singletrack.
The point is, don't let the road bike dogma determine your mountain bike fit. Keep an open mind and do what works.
 

· Recovering couch patato
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13,971 Posts
That small sounds good with a 105mm stem, fit it. Shop should have a Ritchey Comp in a bin to try and even give you to close the deal, as a thanks for helping yourself selling you a bike.
 
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