Stem Length

Run whatever the fast guys run.  Don't listen to some guy who sells stems.

I think the asymmetric thing is way over exaggerated, unless your on some weird old school stem. 

I generally just pick the stem number than means I can get into an easily repeatable, comfy riding position where I don't have to think to much about weighting. Most of my bikes have shorter 35mmish stems, not for that number as such, because that's what makes the frame reach/stack/bar rise and sweep work. 

Richie rude runs a 50mm, Dan booker a 35mm, average the 2 and you the optimal stem length to ride faster and last longer. 

I found myself to be pretty happy at anywhere between 35mm-50mm. If you're not going mach chicken, it's not gonna make a huge difference. You'll probably forget about the length after two rides.

You'll end up ordering the one thats in stock and not back ordered.

I just installed an i9 35 x 40 on a new build.  

I agree with others that 35-50mm is a safe bet, and that the guy in the video you posted is a bit of a kook.

I'm running a 60mm stem on my long travel bike, which is clearly "the wrong size," and it's fine. The reach length of the bike is a little shorter than I'd prefer, so I made it feel longer with the long stem. I've got a 40mm stem on my shorter travel bike (because it has a slightly longer reach length than I'd prefer), and it takes roughly zero feet for me to get used to either bike when I switch. I'd prefer to have the right reach length and a 50mm stem on both, but it's not the end of the world either way.

I want to say, buy a bunch of cheap stems and just try it by yourself. Just hoard them (current stash goes from 35mm to 110mm)

One of my bikes has a 60 mm stem on it because that's what it came with and because it's a Scott, replacing the stem also requires replacing the upper headset cup.  Does that count?

Yes conform, be a sheep don't think for yourself. Certainly don't go out and test to see what works for you...

Ignore whatever stuff Rulezman is spouting/selling.  Don't use a stem for bike fit / reach - that's a roadie thing where they're not turning as much.  Stem length has a big affect on steering feel, compounded by bar width, head angle, and trail gradient.  Try different conventional ones in the 35-50mm length range and see what feels right to you.  If you're sensitive to bike setup, you'll notice even a 2mm difference.  In general, if the steering feels too slow, try shorter, and vice versa (too twitchy go longer).  

That's exactly what I did a few years back.  I tried 35, 38, 40, 42, 45, and 50.  I ended up liking 40 the best for trail/enduro, 42 being ok on my really slack enduro/freeride bikes.  You can often find cast stems from Race Face or the like on sale for <$40/ea... doesn't need to be pretty for trying out feel.

I run a 32mm and it's fine. I would run shorter in the future if possible. If my frame has the correct geo for me, I don't need a long stem.

Do we not all go shorter (35/40mm) cause it looks better though...

Heheh, running what the fast guys run is just as good advice as listening to this guy honestly.  I mean, should we all have the same stack height as Goldstone relative to our height?  Run the same skyscraper bars as Dak?  Why don't we throw Mr. Wilsons reverse stem on there as well.   See where I'm going? Not defending Rulezman, I don't think there is an algorithm you can punch some numbers into to find the correct anything for bike fit.  Bike fit should be intentional, not chasing trends. 

I guess PB did it with the donut, but it would be great to do another redux of it, considering all of the recent trends and see what kinda frankenbike we get. 

I think the matching the fork offset koolaid as close as possible tastes the most neutral.

...

And a nice  high rise bar rolled back to flat.  Perfect.

There's only some weird push-pull imbalance if you think of your torso as fixed.  I can appreciate the feel of a long stem.  You sort of steer with your upper body and you feel like you're flowing.  I generally just use a 50 though.  

The most important thing is to use what feels best to your body on that bike.

I've found a bit of a paradoxical relationship between bike length and stem length. The longer/slacker the bike, the more I want a longer stem as the bike generally has a higher F/R ratio and as the longer stem allows me to place more weight over the front wheel. On shorter wheelbase bikes or bikes with a longer chainstay, lower F/R ratio, I can get away with a shorter stem or taller bars, as I can place more weight over the rear while comfortably loading the front.

35-50mm already gives a "neutral" feeling to the steering - take a long straight edge across your current bars (between the grips) and you will probably find they already intersect the centre of the steerer tube. Running it too much shorter creates the same effect as being too long (ie your hands aren't moving in an arc), except you you lose the "self aligning" stability of a forward facing stem. 

Also you aren't turning a steering wheel here - you don't often turn more than a few degrees outside of switchback

When Brook and the Mondraker team ran stems like this (2012), they had a lot of struggles and the single best improvement to the bike was going back to a "normal" stem

Also if you really feel the need to watch that video, I recommend 1.5x - 2x speed

I tried to work out the front/rear weight bias (corner weight) a while ago, but bought electronic scales that timed out most of the time before i could read them 🤣. I think my weight bias was around 8:1, 12kg front 79kg rear or something like that. This is one of the components you are fucking with if you shorten your stem and from my tests a 5mm change was 1-1.5kg different (quite a big difference). Sounds like Frameworks are onto measuring this (on an angle too) in the latest downtime podcast. For me stems are firstly about adjusting reach. Recently I put 38mm (down from 44mm) rake CSU on my bike out of necessity. More stability yes, any other downsides, maybe a bit more flip flop at slow speed / on climbs. To me this seems to be an avenue where it would be interesting (expensive too) to try shorter rakes / shorter stems and see where you end up. At the same time trying to evaluate what the optimum weight distribution is something I have never heard talked of really.

Reece Wilson has a good video about that BMB stem. Without even testing one myself (I really would like to), wouldn't recommend anyone to even try one with chainstays shorter than 450 preferably longer than that.

While stem length does impact steering feel a lot, I have always found that is of secondary importance to the ease of weighting the front wheel. Maybe I have a weird riding style or just a really strong preference for a lot of weight on the front wheel, but I find it tough to ride anything below a 45mm stem. 45mm feels like the best balance of steering feel to easy weight on the front. 50mm is good, but I find there’s a bit of an oversteer tendency. Under 45mm the steering feels good, but I struggle a bit with front washing. The shorter the stem the more I struggle. This is on size medium bikes with reasonable front to rear center ratios. 

 When setting up a bike, the feeling I seek out is the ability to weight the front wheel for turns without having to move my body weight. If I can just stand on the bike in my natural position and the wheels feel evenly weighted, that’s where I want to be. With a 40mm stem or shorter, I’ve always felt like I have to work to pull myself forwards to weight the front in turns, which increases the risk of front washing. I also find it easier to move my weight back on the bike that forwards, so that probably contributes to this preference. Yes, you can adjust other aspects of the bike to compensate for stem length somewhat (suspension pressures, bar height, etc.) but I’ve never found it fully makes up for a stem that’s not the right length for me. 

All of that to say, don’t just listen to Rulezman’s theories on steering path and lever arms without trying things yourself. I don’t care how well your bike steers, if you can’t trust the front you’re going to have a shitty time. Different riders will be comfortable with different levels of weight on the front via the stem, but I don’t think anyone likes riding a bike that feels like the front is going to wash at any minute.

I will never understand what is with you people and stem lengths. 

Stem length in itself does not matter at all. 

All that matters is where your grips end up being.

You can achieve same bar position with 30mm stem and 50mm rise bar and with 50mm stem with 20mm rise bar. 

Or maybe someone with 30 mm stem and forward roll on bars and ends up being in simmilar position as someone with 50mm stem with backwards roll. 

What we should be meaasuring is middle of grip offset from center of rotation and that is all that could matter if it matters. 

Sincerely someone who has had enough of stem length arguments that don't get to the jist of it. 

Also don't get me started on matching offset and stem lengh.... 

Honestly just run whatever puts your hands where your hands feel like should be and that is it. 

So I'm 6 foot 3. Long torso. Long arms. Think basketball player.  

here's my bikes

Ripmo XL 50mm stem

Oso L 60mm stem

SC Chameleon XL 40mm stem

All have the same handlebar and grips. 

And I love them all. Didn't take any youtube nerd to tell me. But it did take some trial and error. And I've been riding since 94. 

It's all about how you go, your terrain and how you feel. Are you getting good feels? :D 

I always wanted to try a setup like the Mondraker 2011  / Rotec 1998 DH bike setups.  Not sure if I'd like them, but I wanted to try.  These days I'm more of a "DownCountry" guy.  I'm 5'8" and the last XC bike (Pivot M4 SL) I bought was a Large so I could run a 32mm stem.  I loved it.  The extra wheelbase and reach was way more stable at speed than my previous Medium.  The super short stem let me attach steeps much better than any stock XC bike.  I didn't notice a lack of performance in climbing or switchbacks.  Overall I loved it.  I do tend to ride over the front of my bikes so weight transfer has not been a problem for me.  

I like this approach and concur.  I typically try out 40-45-50mm stems on my bikes as I am setting them up and I'm looking for the same front/rear weight balance with regards to cornering that you are looking for.  I feel like it's important to find what feels good, and then go one step beyond that to make sure that what feels good initially is "right".  Same advice for suspension setup, go 2-3 clicks too far and check yourself on better-worse-same.  

I generally end up at 40-42-45mm but most things between 40-50 feel fine to me.  I have at times, experienced bikes where I start to get a windshield wiper effect at 50mm+.  I haven't pinned down what it was that gave that sensation on those few particular bikes where this showed up.  At any rate, more fuel to the fire to make sure you try things out instead of assuming things.  That being said, 45mm is a safe bet, and I haven't found a bike that it didn't feel pretty damn good on.  

Thank you. 

 

Rider here running Rulezman stems on two XXL bikes for over 2 years. Running 75mm rise bars aswell for context. Bars are rolled forward so grips are in line with the fork. Have no issues with front wheel weight/grip. I am yet to wash the front and confidence is at all time high. Took the gamble and it's worked out well for me.

Ahh...well my wife may not like you as much. HA. You know, going shorter for "looks" ....;D

Here is your difference in steering bwetween a 70mm stem and a 35mm stem with straight 800mm bars.


A video to make the scribbely lines more understandable:
https://photos.app.goo.gl/bYf6TE4obQUwvhJG7

As you can see, the rotation diameters are virtually same (406mm vs 401mm). That's about a 1% difference.
Your hands will travel about the same amount: 212mm vs. 210mm for a 30° handlebar turn. That's less than a 1% difference.
What is slightly different is, of course the the "angle of attack" from which your hand will start moving, but that is because a longer stem will stretch your upper body position forward, but that's the whole point of a longer stem.

Mind you, (almost all) relevevant bars are not straight and most bars will put your hands already somewhere close to the steering axis on 35mm stems, and some bars even way "behind" the steering axis.
As @brunch123 already mentioned:
Your stem could be 500mm long and the bar could be the shape of a pretzel: The only thing that matters is where your hands end up being positoned relative to the steering axis. It does not matter how they get there.
Stiffness aside, a 200mm stem with a 170mm setback bar steers exactly the same as 50mm stem with a 20mm setback bar.
Choose the stem that fits best where your hands feel comfortable, but don't expect it to have influence on steering "directness". It will feel different because your cockpit is longer, but your hands won't travel more just because the stem is longer or shorter. Especially not, when looking at common stem lengths between 30 and 70mm.