I’m getting tempted by some of the wider flat bars that are now being produced for my XC race bike. I currently run 580mm flat bar with a 100mm stem, if I put on a wider bar is it a good idea to shorten the stem length to prevent it getting twitchy?

Shorter stems make handling more twitchy… so not sure if your thinking is in the right direction. I would, however, always suggest wider bars and shorter stems as twitchy often = quicker and more responsive.

580mm is horribly narrow. I tried my wife’s commuting bike with 560mm bars recently and felt like I had absolutely no control at all.

Try the wider bars and if your reach is ok leave the stem alone, but if you can get a cheap 70-80mm stem give it a go to see what you think.

580mm is old skool! Thanks though, I’ll just keep the stem the same and play with bar width for now. I only asked as everyone seems to have their bars sat on top of the steerer tube these days and I thought I was missing something.

Shorter stems make handling more twitchy

Not exactly. Steering is more direct the closer the bar is to the perpendicular of the front axle. A shorter stem increases the trail and makes the steering less twitchy, i.e. slower.

If you use a very narrow bar with a short stem, then you have to over-emphasise steering input which can result in over-steering, hence the twitchy “feel”.

A wider bar counteracts this by giving you more leverage.

The handling of my Alpine is much more predictable now it has a 740mm bar and 50mm stem over the 680/70mm combo it came with.

A shorter stem increases the trail and makes the steering less twitchy, i.e. slower.

Definitely do not agree. This based on actually trying the same bars with different stem lengths.

Disagree. A shorter stem increases the trail and makes the steering less twitchy, i.e. slower. The wider bar counteracts this by giving you more leverage.

The handling of my Alpine is much more predictable now it has a 740mm bar and 50mm stem over the 680/70mm combo it came with.

To come to a conclusion you can only change 1 thing at a time…

Buy the bar first and try it with your stem, Unless your old stem isn’t oversize.

Definitely do not agree.

Think about it – road bikes and XC race bikes have a narrow bar/long stem combo in general. This puts the bars closer to the front axle. The closer you get to the front axle, the more immediate (twitchier) the steering (compare a Harley Davidson with an R1).

Twitchy steering on a gravity-orientated bike is undesirable – therefore a shorter stem is used, but a wider bar is necessary to increase the amoutn of leverage available, thus reducing the risk of over-input.

Try running the same bars with different stem lengths and leave the “science” for someone else. 😉

I can absolutely guarantee that you are wrong.

johnellison

you are arguing stem and bar length together so the output is the combination of both not just reducing stem length.

Twitchy steering on a gravity-orientated bike is undesirable – therefore a shorter stem is used, but a wider bar is necessary to increase the amoutn of leverage available, thus reducing the risk of over-input.

Rubbish. The wide bars provide stability but slow steering (as greater input is required to turn the bars), hence a short stem to speed up the steering which if you had narrower bars, would be twitchy.

wider bars and shorter stem for the same overall fit

it’s not twitchy it’s balancy

go run around the park with your hands out in front of you on straight arms, you have to point to where you want to go (that’s long stem narrow bars)

now run around with your arms out to the side, like you are playing aeroplanes, you lean to where you want to go (that’s short stem wide bars)

Isn’t the point about having a shorter stem with wider bars mainly that by widening your bars you are effectively bringing your weight further forward – shortening the stem offsets against this.

I have been playing with bar and stem lengths on a couple of my bikes. Not because I wanted too for wide bar fashion reasons more to get the bikes feeling how I like them. On my stiffee that I was changing from a freeride bike to more of a pedaller I changed from a 50mm stem and higher riser bars to a lower rise 680mm bars and a 110mm stem. this felt awful. like I was sweeping the bars around instead of turning them. The steering felt very slow. This was solved by fitting a 90mm stem. Then I changed my forks from Marzocchi shivers to fox f120’s and the steering felt too fast. So I tried the 110mm stem and it was perfect. On my Anthem I tied a low rise 660mm bar and a 90mm stem which again was ok until I dropped the fox forks from 120mm to 100mm. I swapped the stem to a 110 and its now perfect.

I personally find wide bars a bit stupid and awkward. Definitely marketing bs. Give it a few years and the mags will be telling us that narrow bars are the best. Whatever works for people though.

Andy

I’d really like to get on with longer bars and wider stems, it seems like what the cool kids all do. I bought some Sunline 745s and I’ve gradually cut them down, 1 more cut and they’re the same as my 685s that I really get on with. Rubbish 🙁

wider bars and shorter stem for the same overall fit

it’s not twitchy it’s balancy

go run around the park with your hands out in front of you on straight arms, you have to point to where you want to go (that’s long stem narrow bars)

now run around with your arms out to the side, like you are playing aeroplanes, you lean to where you want to go (that’s short stem wide bars)

b*****s

never that simple. throw in the fork rake, head angle, stem length, bar width, wheelbase, bb height. then consider whether you are riding in woods etc.

The best handling bike i have ever riden is a Bontrager race, narrow bars, long stem, steep angles, but, no steering, ever, you thought it went.

In general non-specific terms
Wider bars = slower steering, narrower means more twitchy.
Longer stem = slower steering, shorter means more twitchy.

Typically people who get wider bars tend to shorten the stem to compensate for the slower steering created by the wider bars.

Oh right, can opened worms everywhere.
The only thing stem length and bar width change is the torque required for steering inputs. Twitchiness is mostly a function of trail ( the distance the actual wheel contacts the ground vs an imaginary line down from the steering axis. Road bikes feel more twitchy because generally they have more trail than mountain bikes. If you haven’t changed the trail on your bike it’s no more twitchy or otherwise than it was before, just the effort required to initiate a change in direction has changed.

Bike steering dynamics is waaaay more complex than just stem and bars.

OP are you familiar with the handlebar/front hub fit thing? When seated in a neutral riding position the bar around the stem should obscure the front hub when you look at it in olde bike fit rules. Too much bar in front is likely to be uncomfortable and slow steering, too much behind will not be good for climbing and likely to be a bit twitchy. Spacers and saddle position will have an impact on this too.

It’s a rule of thumb, not a hard and fast but still appears relevant. I think this originates from road but it works for MTB too.

I use 711mm bars with a 60mm stem, any wider and I’d lose fingers from punching trees and the stem feels a good compromise for climbing and playing around.

You’re going from pretty tight bars, maybe give a 700mm flat bar & 70mm stem a go? I don’t know how your controls are spaced but you may have a bit more room on a wider bar to have more of a 1 finger braking position than the older 2 by moving your brakes inboard of the shifters (you’re probably aware of this, but it helps if you’re not!).

Whether you like wider bars is just a matter of personal preferance and is bound to be affected by where you ride. It’s going to be really annoying if your regular ride takes you through tight tree runs and you’ve got some 780mm bars fitted!

Personnally I’m going through a wide phase at the moment. I changed my 680mm bars last year for some 750mm wide ones on an 80mm stem and the steering definately felt slower, but I also found it harder to find that sweet spot when descending, probably because it had brought my weight forward a bit. I then changed my stem to 55mm and what a difference that made!! The steering was noticeably quicker and I felt more centred on the bike again.
Hasn’t stopped me crashing though, so it’s not been the transformed me into a riding god, but hey, what would? 😉

OP are you familiar with the handlebar/front hub fit thing?

Yup – I had read that if you widened your bars you should shorten the stem, but I just wasn’t sure why.

I don’t know how your controls are spaced but you may have a bit more room on a wider bar to have more of a 1 finger braking position than the older 2 by moving your brakes inboard of the shifters

They fit ok on the 580 bar (bit tight with bar ends).

I’m hoping a wider bar will be better for sprinting as at the moment I find the narrow bar just a little too narrow to properly haul on.

And with a longer stem, you are putting more weight over the front…I’ve just gone from a 100x10deg stem to a 110x0deg stem, still debating whether i like the feel. It seems at odds with a 120mm travel FS bike, but i’d love to put flat bars on it too!

Wider bar increases the relative reach… I tend to follow a very rough 2:1 rule, so a 40mm increase in bar width would see me drop 20mm in the stem length.

Recently went from 700mm bars and 70mm stem to 740 bars and 50 stem, seemed to work. The wider bar tends to compensate for the shorter stem so don’t assume shorter stem will be twitchier either.

So I’d try going up to say 620mm and down to 80mm stem…

Disagree. A shorter stem increases the trail and makes the steering less twitchy, i.e. slower. The wider bar counteracts this by giving you more leverage.

LOL

Imagine an infinitely long stem, it would take an infinite amount of movement to turn it. An in-line has a direct response.

All I know is that with 780mm bars and a 50mm stem I can make corners I previously wouldn’t have made, whether due to the wheel being wrenched over a divot of grass, or the sheer force that can be applied. I HAVE found myself physically heaving HARD and being very pleased with the outcome at times when I know I should be lying on the ground instead.

I don’t consider 110-90mm as changing to a short stem. BUT, this is XC racing you’re talking about and I know it’s different.

All I know is that with 780mm bars and a 50mm stem I can make corners I previously wouldn’t have made, whether due to the wheel being wrenched over a divot of grass, or the sheer force that can be applied. I HAVE found myself physically heaving HARD and being very pleased with the outcome at times when I know I should be lying on the ground instead.

Hmm sounds like a skill compensator, thought you were against those? 😉

A lot of modern day XC race bikes/racers opt for stems ranging from 80-120 with most 29er users go from -5 to -17 deg stem.

i race with 700mm bars with 90mm -17deg stem on 29er to get the front end low enough, mind you each to his own really and what feels right to you.