compensate long top tube with short stem?

[Ned Mantei]

Will a short stem lead to unacceptably "twitchy" steering?

After 20 years on road/touring bikes I am about to buy my first mountain bike. I am interested in
good components that will last a long time. However, the mountain bikes with better parts (LX/XT on
up) generally seem to be "racing" models, with relatively long effective top tube length. The Trek
8000,for example, has an effective top tube length of 64 cm for a 21.5-inch frame. By comparison, my
present touring bike has a 57 cm top tube length on a 60 cm frame. I like the somewhat more upright
position that the touring frame allows--not bolt upright, but enough that I can ride in a relaxed
position. A bike with geometry similar to that of the Trek, including a similar stem, required more
stretch than I care for. Presumably I could compensate for the long top tube of the Trek frame with
a stem that is quite short and has vertical rise. How well would one expect this to work out? Will
the steering become noticeably "twitchy" with the short stem? An alternative might be to buy a
cheaper bike meant for "recreational" riders--the manufacturers apparently assume that occasional
riders will want to sit more upright and design the frames accordingly.

--
Ned Mantei Department of Cell Biology, Swiss Federal Institute of Technology CH-8093 Zurich,
Switzerland

 

[Chris Zacho "Th]

The reason stems come in different lengths is to "tweak" the length from saddle to handlebar.
Every frame builder knows that all bodies are not built equally. The idea is to get the frame
who's geometry comes as close as possibly to you own geometry, then choose the stem length that
makes it perfect.

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": http://www.geocities.com/czcorner

 

[Jon Bond]

"Ned Mantei" <[email protected]> wrote in message
news:[email protected]...
> Will a short stem lead to unacceptably "twitchy" steering?
>
> After 20 years on road/touring bikes I am about to buy my first mountain bike. I am interested in
> good components that will last a long time. However, the mountain bikes with better parts (LX/XT
> on up) generally seem to be "racing" models, with relatively long effective top tube length. The
> Trek 8000,for example, has an effective top tube length of 64 cm for a 21.5-inch frame. By
> comparison, my present touring bike has a 57 cm top tube length on a 60 cm frame. I like the
> somewhat more upright position that the touring frame allows--not bolt upright, but enough that I
> can ride in a relaxed position. A bike with geometry similar to that of the Trek, including a
> similar stem, required more stretch than I care for. Presumably I could compensate for the long
> top tube of the Trek frame with a stem that is quite short and has vertical rise. How well would
> one expect this to work out? Will the steering become noticeably "twitchy" with the short stem? An
> alternative might be to buy a cheaper bike meant for "recreational" riders--the manufacturers
> apparently assume that occasional riders will want to sit more upright and design the frames
> accordingly.
>
> --
> Ned Mantei Department of Cell Biology, Swiss Federal Institute of Technology CH-8093 Zurich,
> Switzerland

A mountain bike is supposed to be a lot smaller than a road bike. If its too large, not only will it
be harder to control at slow speeds, and harder to "flick around", it will also make for
uncomfortable dismounts.

The most important thing to look for in a mountain bike is top tube length. Don't look at numbers -
just go ride them. Go to your local bike shop, preferably one where they know their stuff, and have
them fit you. My guess is that you'll find yourself in either a size large frame or on a different
geometry frame with a shorter top tube.

Jon Bond