top tube / stem length trade-off
This is a question I've seen asked before but can't remember seeing a convincing answer to.
If you are fitted properly for a road bike you will have an ideal reach to the handlebars, which should be determined by the combination of tube tube length and stem length. Saddle position shouldn't come into it, as that should be determined by the ideal position in relation to the bottom bracket.
Now, extra short stems (90mm or less) and extra long stems (140mm or more) have disadvantages, but it seems that anything between 100mm and 130mm is perfectly OK. So in my own situation I could equally have a top tube of 57cm and a stem of 100mm, or a top tube of 54cm and a stem of 130mm. As it happens I have the former (57/100), so I am near one end of this spectrum. The ride is lovely and I'm 100% happy with it, but I'm curious what differences, if any, I would notice if I had 54/130 instead, all other things being equal.
If you are fitted properly for a road bike you will have an ideal reach to the handlebars, which should be determined by the combination of tube tube length and stem length. Saddle position shouldn't come into it, as that should be determined by the ideal position in relation to the bottom bracket.
Now, extra short stems (90mm or less) and extra long stems (140mm or more) have disadvantages, but it seems that anything between 100mm and 130mm is perfectly OK. So in my own situation I could equally have a top tube of 57cm and a stem of 100mm, or a top tube of 54cm and a stem of 130mm. As it happens I have the former (57/100), so I am near one end of this spectrum. The ride is lovely and I'm 100% happy with it, but I'm curious what differences, if any, I would notice if I had 54/130 instead, all other things being equal.
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A shorter stem makes the steering more responsive to hand input. That is it is more 'twitchy'. With a longer stem steering input is more of a side to side movement. I have fitted a 120mm stem to all my bikes so they feel the same. They all have about 55.5 / 56cm TTs.I can really feel the difference on my MTB with straight bars. If you went to a 130 from a 100, with the apropriate TT length, it would feel a bit like steering a barge at first. You would soon get used to it and may even like it.0
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Yeah, I'd heard that a short stem = twitchy, but my 100mm doesn't seem twitchy to me at all, I guess because I'm used to it. My MTB is certainly a A LOT more twitchy. I suppose as you are on the hoods most of the time, the stem only accounts for about half of the extension or less, so the diff. between 100 and 130 (or 230 and 260 in effect) isn't so great.
The other thing that occurs to me is that if you go for a short TT and longer stem, your wheelbase is likely to be shorter which in itself would tend to make the bike more twitchy? So I wonder if the two mostly cancel each other out in practice and it doesn't actually make much difference.0 -
I've got a 90mm stem on my commuting bike, spend most of the time on the hoods at moment, and don't find the steering twitchy.
I'm building up a carbon bike at the moment and I've got a 120mm stem to go on it, the top tube is slightly shorter (maybe only 1cm or 2cm) than my other bike. But due to the other differences in geometry I went for 120mm rather than 100mm or 110mm.
I think the stem length doesn't just depend on top tube length, but the length and angle of the headtube and how many spacers you put underneath the bars.0 -
There's been a previous thread somewhere on this where the majority view was that shorter stem makes handling faster/more twitchy. I'm not convinced about the leverage argument given that steering is mostly by leaning. Perhaps weight distribution is the reason in that less weight over the front wheel from a shorter stem could make things twitchy?
For tall people with a short reach (like me) this is a topic of some interest.
DaveDavid Jones0
