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ideal stem length?(4 posts)

ideal stem length?CrazyMan
Jun 29, 2003 10:48 PM
(sorry), yet another geometry question unrelated to the last.
just wondering what would be the ideal stem length.
I've been firt as a 57.5 top tube with a 120 stem.
With the same s.t. angle, how would going to a 56.5 tt with a 130 stem change the character of the bicycle?
thanks in advance
FAQ...C-40
Jun 30, 2003 5:06 AM
Another frequently asked question. You probably won't like this answer either.

Just because a fitter measured you and came up with 57.5mm TT and 120mm stem does not mean it is ideal, nor is there a guarantee that you will find it comfortable or "optimum".

What if you later find that moving the saddle back 1cm allows you to produce more power? Then you'll need a shorter stem to maintain the same reach. A fitter has no way to know what saddle position will ultimately be the best for you.

There is no "ideal" stem length. I've used a 100,110 and 120mm stems on the same frame while I experimented with saddle fore/aft position. None of the lengths was detrimental to the handling or steering of the bike.

The steering arm length, is only changed by 15% when the stem length is increased from 80mm to 120mm. Longer stems will steer a tiny bit slower. A bike is not steered by turning the handle bars at normal riding speeds. Most of the turning is done by leaning into the direction of the turn. Also, whatever stem length you end up with, it will feel "normal" to you after a few rides, regardless of what you've been using in the past.

From a weight distribution standpoint, the shorter TT frame would most likely have a 1cm shorter wheelbase, 1% more weight on the front wheel and 1% less on the rear wheel. The shorter wheelbase may make the bike feel a bit more nimble, IF there are not other changes made to the geometry to slow the steering and increase the wheelbase. I've got two bikes with this type of difference right now. My Fondriest has a 1cm shorter front-center dimension and a shorter TT length that requires a 10mm longer stem than my Colnago C-40. At slow speeds, the Fondriest may turn a bit quicker, but at normal riding speeds, I can't tell much difference. The disadvantage that you may experience with with a frame that has a short F-C is toe overlap with the front wheel. The Fondriest is the smallest frame I've ever owned, and the first that has toe overlap. Toe overlap is never a problem while riding, but you have to be careful when starting off from a stop sign. Turn the wheel too far and you may find your toe on the wrong side of the wheel.
i LOVE C40...nmCrazyMan
Jun 30, 2003 2:44 PM
i LOVE C40...nmzippi
Jun 30, 2003 8:39 PM
agree, thank you for clarifying so many questions that most bike shop "salesmen" have trouble with or don't want you to know. thank you, zippi