Yes, bar dimensions are the other part of the equation! Different combinations of stems and bars (not to mention number of spacers, angle of bars and location of shifters on bars) can be used to position your hands in the same place in space relative to the steerer tube. It seems kind of silly to talk about ideal stem length without at least taking bar dimensions into account. E.g., if you think 100mm is your ideal stem length with Ergonova bars (77mm reach), then 90mm would become your ideal with Ergosum bars (89mm reach), everything else being equal.

@Prendrefeu: you left trail out of the equation. Afaik that will also influence the feel of the bike by influencing how strong the "centering tendency" will be, making the bike more or less nervous/agile/quick to respond.

Calfee has an interesting page on geometry: http://www.calfeedesign.com/tech-papers ... -handling/

In the end, I guess, all a gigantic "it depends"

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power2max

So I guess we can agree that there is no one variable that determines the handling of the bike?

My point is that people keep pointing at the stem and then give off some (rather daft) line like "short stems make for poor handling" when, really, it's more than the stem at play.

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Exp001

Well if a longer stem has their weight better distributed then surely there's a truth of sorts to what they are saying.

It's case specific, but still not untrue on what they're claiming.

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Not to make the topic more controversial but I have been pondering over MTB geometry these days and it seems "Mounties" (sounds weird) are much less finicky than roadies as MTBs have head angle ranging from 71 to even 64 degrees. Even for hardtails it ranges from 66 to 71, but for roadies, half a degree is a pretty big deal.

BTW, my bikes tend to look best with 120 stems but handling feels best with 110mm.

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+1.
Nobody claims that the length of the stem alone defines a better ride. But usually (that is in most cases) an x rider on a y road frame (which is the right size for him) will have a better weight distribution (and better steering, feedback etc) on a 110-130 stem. That does not work as a rule of thumb for everyone but in most cases it does.

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Its not just the angle, its also the fork offset and the weight of the wheels.

That's just the front end alone. The BB drop, the rear stay length, seat-tube angle ( which affects the positioning of the rider's center of gravity) all have a role to play.

As for the part about half a degree making a huge difference in road bikes, try fitting up with size 700x32c tyres that weigh closer to 400g grams each. You'll find that the handling sensitivity becomes much more muted compared to a 23c tyre.

Well, notwithstanding that 'size doesn't matter', it is true that a longer stem does have the effect of slowing-down steering on a bike. I guess, for me, that is one of the benefits of the requirement of 140mm stems caused by monocoque frames...

I use 110mm stem, it works well for me.

130mm -17

115, though not sure who still makes them. Deda used to and you could find them from European distributors.

For me it's more about weight distribution and how much the extra or less stretch allows me to push the front wheel on descents.

Run a -17 120 on my Canyon CF '12(60) and same on an Allez '10 (58) - the Allez feels a lot better even though the overall geo is similar. Just about to try and change the bars from Allez over to Canyon to see if it makes it better.

100-120mm user here.

I've got a 105mm on my road bike and 120mm on a build that's upcoming.

I agree with TP and prendref, but I'm going to align with Nick here. It's more about weight distribution than handling. Although that affects how the bike feels, I don't think that's a direct parallel with handling as such, but it's related. I agree with prendref in that changing stems has a minor effect on actual bike handling.

I'm running a very short (50 or 60mm) stem on my TT bike, which, when sitting up, puts my weight too far back and makes the bike feel a bit vague at the front. When I'm in position, however, it feels spot on. Similar to road bikes, you don't corner in the same positions as you spin along in. The bike's handling will be affected by the wheelbase and fork geometry, and your body will shift around to find a good cornering position.

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it is about a balance.

for me at 185cm i am in between sizes on a lot of stock sized frames.

with longer legs for my height, i require a seat height of 79cm. the TT of a "56" is about right for me, but the HT is often a bit short, and the wheel base with that seat height makes for a high CG and a little Twitchy. i ride a 56cm TT, 120mm stem and 90mm reach bars, 170mm HT and a 20mm high stack headset top cap.

on a 58 i really only need a 110mm stem to obtain correct reach, which unfortunately on a lot of 58s is too short with a lot of them having quite steep HTA (73.5-74).

a longer stem slows the steering response for a given amount of input. seated and riding in a bunch this is definitely an advantage. the other side to it though is if youre running a longer stem, youre often on a smaller frame, with a shorter wheelbase. you need to balance all of these factors depending on you fit and riding style.

sprinting is another issue. when you stand you inevitably move forward, and overly long stem (coupled to a shorter wheel base) makes the bike unstable when sprinting.

i would actually prefer to go a little shorter stem, with a slightly longer TT and a nice mellow HTA for a little bit more stability.. 57 tt, 110 stem, 72/72.5* HTA 45mm rake would be the perfect compromise.

With 585mm TT - 110mm Stem

With 575mm TT - 120mm stem

Saddle to bar drop 14cm.