Stem lengths?

[ishaw]

I've got a few builds I'm messing with and in some cases looking to use modern parts on retro frames, in others retro all the way.

I'm more used to building around 110-130mm stems with flat bars, but have also got a few builds with shorter stems and risers.

Appreciate that it is mostly down to.personal taste and feel, but what are the merits of shorter stems and risers over longer stems and flat bars?

Exhibit A. My dbr axis tt was wearing a titec ti stem at 110mm and flat titec ti bar at approx 560mm. Today i've fitted a hope stem at 90m and a low riser bar which is much longer than the 560mm I had on previously. I've done this because I had the parts and have also replaced the rest of the build with m970 drive train, modern wheels etc. I've not had a chance to ride it yet as I still have a few things to fettle, but what difference will this make?

Main reason for doing this is I've bad knees and back/neck so hoping for a little more comfort, but what impact will it have on the ride?

I am contemplating similar changes on at least one other retro steed, but before I do, wanted some advice on whether the change will be good or bad?

Also just keen to understand a bit more about what it all means from a technical perspective as I grew up with short bars and long stems, high sets post and the world has moved on from that. Not all change is good, some is simply chasing new sales and profit, so what are the benefits/drawbacks?

 

[FluffyChicken]

Re:

Most change happened because the forks got longer due to suspension.
Which changed the setup and pushed the front up higher.

As to how it will alter your bikes, no idea.
When I shortened the front with wider but flat bars of a late 90s bike, my front became lighter and jittery when riding the Moors. Oddly a bugger when it was windy.

Honestly, I wouldn't worry. Try it and see what it feels like. Some tyres and suspension setups (damping and poorly set springs) can alter things badly too.

 

[CassidyAce]

Re:

This should help: https://www.pinkbike.com/news/exploring ... ength.html.

And so should this: https://cyclingtips.com/2015/03/how-doe ... -handling/

Roughly speaking, a shorter stem will make the steering more twitchy/sharper and wider bars will compensate for that by increasing the steering arc: you have to move your hands through a greater distance for each degree of turn. Wider bars will also tend to shift your weight forward and give more leverage, which is useful on a mountain bike. However, a longer stem will also increase the steering arc, make the steering feel less twitchy and shift your weight further forward but, combined with narrow bars, will not give you that extra leverage, so this approach is perhaps better suited to road bikes where leverage is not so important but being aerodynamic is.

And then there are a whole load of complexities relating to head angle, offset, steering wheels and tillers, etc.

 

[2manyoranges]

Re:

As C Ace states, it's a horrible mass of geometric interactions which is entirely understandable and model-able but only resolved by 'stick it on and see what happens'.

Grief, in 1988 I had an 18 inch Cannondale with a short top tube (what I know would regard as a stupid-short) and we compensated with a 150mm stem. 150mm!!! I still have it somewhere.

The thing is...mountain biking has changed in its ethos and style. We were interested in climbing in the 80s and 90s. Downhill was just terrifying, owing to the non-existent braking ability of bendy components and useless geometry in the cabling. It was deadful. Forget Pedersen Self Actuating brakes and Aztec brake blocks. It was shit and we knew it. So MTBing was about cutting down time on the hills and tiptoeing down descents. The weight on the front wheel from a longer stem - 135-150 really helped on climbs - you could balance weight exactly between front (steering) and rear (traction). And will a Porc on the front and a Ritchey on the back you could get up anything.

Then came V brakes. Ah ha...brakes which worked. So stems got shorter (i'm talking 120-135 here), and bars got a bit wider. And you went downhill faster. But the bikes still climbed, and that was still the main point of MTB-ing - fast thrashing on the flat, hacking up impossible climbs, and you still tiptoed down descents, for fear of being thrown over the bars.

Then came Jason M. He just put down his seat, went hell for leather and the whole scene started to change.

Roll forward 20 years and stems started to change since brakes evolved. Proper discs meant control. Suddenly you could push really really hard downhill. Getting suspension travel up was no sweat for the likes of Fox.

So stems got short. We run 35mm on a lot of our XC, DH and jump bikes. With 780 bars. These bikes are useless on the climbs we used to romp up. I mean useless. The front wanders all over the place, finding the balance point between front and rear is like walking a tightrope over Niagara Falls, and its all a terrible fuss. But downhill...…..yo!

So when you look at a stem - quill, ahead, 1inch, 135, 35 - you are looking not only at front end traction versus downhill safety/ability; you are looking at fashion - and Zeitgeist. The Spirit of the Times.

 

[ishaw]

Re:

Thanks, that's useful info.

I'm not setting out to race, push hard, climb like a goat or descend like a boulder. Just want some comfort to get me out and make the bikes I want to keep more ridable.

 

[2manyoranges]

Re:

Reach is now one of the more important measurements on a bike. Have a look at the reach on the bikes you are building. And also factor in seat angle, which is affected by in-line or setback post clamp, and position of the saddle on the rails.

Even in the 90s we were playing with loooong top tubes (Marin team) and shorter stems (100/110) and in line posts. If a bike is too short in the TT, a long stem pushes you out so that your neck has to go up too far to see forward, and pushing the seat back slackens the seat angle so you are pushing forward with your legs and actually in a kind of useless foetal position.

So we were doing what Cy Turner did with the COTIC soul and certainly his now really long Solaris Max - long top tube, short stem, steep seat angle. Stretched position, but no strain on the neck trying to look forward, since the bb is well back.

 

[Brotrob]

Re:

As C Ace states, it's a horrible mass of geometric interactions which is entirely understandable and model-able but only resolved by 'stick it on and see what happens'.

Grief, in 1988 I had an 18 inch Cannondale with a short top tube (what I know would regard as a stupid-short) and we compensated with a 150mm stem. 150mm!!! I still have it somewhere.

The thing is...mountain biking has changed in its ethos and style. We were interested in climbing in the 80s and 90s. Downhill was just terrifying, owing to the non-existent braking ability of bendy components and useless geometry in the cabling. It was deadful. Forget Pedersen Self Actuating brakes and Aztec brake blocks. It was shit and we knew it. So MTBing was about cutting down time on the hills and tiptoeing down descents. The weight on the front wheel from a longer stem - 135-150 really helped on climbs - you could balance weight exactly between front (steering) and rear (traction). And will a Porc on the front and a Ritchey on the back you could get up anything.

Then came V brakes. Ah ha...brakes which worked. So stems got shorter (i'm talking 120-135 here), and bars got a bit wider. And you went downhill faster. But the bikes still climbed, and that was still the main point of MTB-ing - fast thrashing on the flat, hacking up impossible climbs, and you still tiptoed down descents, for fear of being thrown over the bars.

Then came Jason M. He just put down his seat, went hell for leather and the whole scene started to change.

Roll forward 20 years and stems started to change since brakes evolved. Proper discs meant control. Suddenly you could push really really hard downhill. Getting suspension travel up was no sweat for the likes of Fox.

So stems got short. We run 35mm on a lot of our XC, DH and jump bikes. With 780 bars. These bikes are useless on the climbs we used to romp up. I mean useless. The front wanders all over the place, finding the balance point between front and rear is like walking a tightrope over Niagara Falls, and its all a terrible fuss. But downhill...…..yo!

So when you look at a stem - quill, ahead, 1inch, 135, 35 - you are looking not only at front end traction versus downhill safety/ability; you are looking at fashion - and Zeitgeist. The Spirit of the Times.

What a great, value adding post - thank you!

 

[MattiThundrrr]

There is leverage to consider when changing bars and stems. The modern trend towards wide bars is because more lever is required to move the big heavy wheels and to fight the "chopper flop" inherent in low steering angles. When changing your levers, maintaining this becomes important. Widening the bars without shortening the stem would add to the lever length, making the steering more twitchy. I've heard of a formula which connects the two, for every cm of stem removed, add two cms of bar width, and the steering feel should remain relatively unchanged

 

[joglo]

just adding a nice picture,
It's not from me, but I haven't asked the owner neither, if someone has a concern, just let me know


Just because this fits nicely to what @MattiThundrrr has said and illustrates nicely that stem length but also bar length do have quite a bit of impact on steering behavior.
The picture compares a long and short stem with same bar plus a short stem with a wider bar.

For same change of 10° of steering the long stem with short bar need most longitudinal movement of the bars at the side (x, y or z).
As shorter the bar and as shorter the stem smaller movements lead to bigger change of direction.

Having a too short stem, or too short bar can lead to an nervous steering. Wide bars need also short stems.

Rule of thumb: same longitudinal movement of the bar at the side with a 6cm wider bar leads to 1° less change of steering angle.

 

[Tootyred]

Try this...if you cant get comfortable you can use it to swap about....or you can see the change in reach/ stack by swapping a stem out.

I found it good to work out if i say wanted the bars 10mm closer, but 30mm higher than what I've got as a test stem, how to get it and what to shop for.

https://reverse-components.com/en/content/stem-calculator