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Stem Length

canadmos

canadmos

Cake Tease
May 29, 2011
21,708
21,152
Canaderp
I haven't fiddled with changing the stem on my bikes in a long time...

Currently I have a 32 or 35mm length stem on my medium Banshee Rune, with a DVO Diamond fork of unknown offset. I've had this setup for a year.

It mostly feels good, but the front end is kinda wobbly on flatter landings and it kind of feels like the bike wants to flop over if I dig deep into some turns.

What characteristics should I expect if I get a longer stem, let's say 50mm?
 
R

Rhubarb

Monkey
Jan 11, 2009
463
238
I tried a 40mm stem with an older Lyrik (so pre short offset era), and on and older size large frame (slightly shorter Reach than current standards). Thought a shorter stem would help with attacking the trail but I ended up missing all my turns. Felt good on the jumps though. Went back to 50mm and restored trail harmony. On my newer bike with longer Reach, but not short offset fork, 40mm works fine. Currently riding/testing the same fork on a different bike with a little less reach and using a 50mm stem. Best option is to have a couple of stems and ride trails you know well and like (has mixed features you enjoy riding).
 
djjohnr

djjohnr

Turbo Monkey
Apr 21, 2002
3,104
1,795
Northern California
Buy a few stems in 5mm increments - 40, 45, 50. Test them and run what works best as it usually varies by bike. I'm at 50mm on V3 Bronson, 40mm on a Commencal Clash, and 55mm on a Glory.
 
HAB

HAB

Chelsea from Seattle
Apr 28, 2007
11,586
2,018
Seattle
If we're talking direct mount:

Syntace
Gamut
Easton
I think Deity did a 50/55mn adjustable one

Edit: we're not talking direct mount!

Still Easton
 
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ChrisRobin

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,385
205
Vancouver
I've always found it strange that a lot of companies would offer a 35mm stem, then the next size up was all the way at 50mm. I had to look hard to get a 40mm stem locally.
 
Sandwich

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,599
6,788
borcester rhymes
canadmos said:
What characteristics should I expect if I get a longer stem, let's say 50mm?
Click to expand...
i spent some time swapping from 28 to 50mm stems on my downhill bike, back to back. the 50mm was more aggressive and faster handling. The 28 was slow and dumb. I think short stems are great for going fast but handling slow, and 50s are pretty on point for a solid handling bike. There have been a few threads about offset v stem length which might be interesting to dive into, but I think 45-55mm stems are spot on for handling unless you're going mach stupid all the time. I like my 28 for diving through trees, but less so for aggressive corners- requires more body englinsh and effort
 
canadmos

canadmos

Cake Tease
May 29, 2011
21,708
21,152
Canaderp
Sandwich said:
i spent some time swapping from 28 to 50mm stems on my downhill bike, back to back. the 50mm was more aggressive and faster handling. The 28 was slow and dumb. I think short stems are great for going fast but handling slow, and 50s are pretty on point for a solid handling bike. There have been a few threads about offset v stem length which might be interesting to dive into, but I think 45-55mm stems are spot on for handling unless you're going mach stupid all the time. I like my 28 for diving through trees, but less so for aggressive corners- requires more body englinsh and effort
Click to expand...
I purchased a 50mm Chromag stem, so as soon as it shows up, I will try it now.
 
ZHendo

ZHendo

Turbo Monkey
Oct 29, 2006
1,661
147
PNW
I tried to be cool and ride a 35mm stem, and hated it. In my experience, there's a weird handling characteristic when running a stem shorter than fork offset that makes intentional steering inputs feel muted, but doesn't actually improve stability much. I think its one of the issues that has plagued bikes that have too long of reach (yes, I believe that's a thing) and makes them feel super stable, but unresponsive to rider input.

For what its worth, the new Spank Split stems come in a bunch of weird lengths that make it pretty easy to find 'tweener sizes. I ran a 43mm stem on my Transition Sentinel with a 42mm offset fork and liked it, now running a 50mm stem on my 42mm offset fork on a Banshee Titan which works well too.
 
Bikael Molton

Bikael Molton

goofy for life
Jun 9, 2003
4,088
1,235
El Lay
I haven't been paying too much attention to the whole offset business... what stem length would you guys recommend for a 46mm offset 27.5 Lyrik?
 
M

marshalolson

Turbo Monkey
May 25, 2006
1,774
531
ZHendo said:
I tried to be cool and ride a 35mm stem, and hated it. In my experience, there's a weird handling characteristic when running a stem shorter than fork offset that makes intentional steering inputs feel muted, but doesn't actually improve stability much ... snip ... I ran a 43mm stem on my Transition Sentinel with a 42mm offset fork and liked it, now running a 50mm stem on my 42mm offset fork on a Banshee Titan which works well too.
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:stupid:

Of the firm belief that stems are for handling, not sizing.

Data set of one over here, but:
51mm fork offset = 50mm stem felt best
44mm fork offset = 45mm stem felt best

felt like 35mm stems cornered really wonky for me (6'2'' human) with either 50mm or 44mm forks.
your mileage may vary, and all of that.

and the good news is that buying and selling used stems on PB / Ebay to try lengths is super easy and very cheap if you are not crazy picky about what it is.
 
englertracing

englertracing

you owe me a sandwich
Mar 5, 2012
1,649
1,137
La Verne
This whole conversation has already happened, and i think its dumb to match a stem to offset, as shorter offset means more trail,
For the geometrically impared, trail is the distance from your head tube axis' intersection with the ground and your tire's contact with the ground.

So why would one think that shorter offset, that creates more trail and slower more stable steering, would allow for a shorter stem that feels more numb??
Why would one think that longer offset, that creates less trail and quicker less stable steering, would allow for a longer stem that feels more twitchy??

Im trying to say that the theory that stem length shouldn't be less than offset "because dey shoulf match MOAR better" is at best half baked

Couldnt it be possible at a 35mm stems suck for some other reason reguardless of long or short offset?

Hows about the distance from the riders center of mass to the steering axis and the effect the stem length has on shifting that relationship fore and aft?

Hows it steer with your head behind the steering axis? How bout with the steerer aiming through your chest? Now - yes - A ton if it has to do with weight distribution but i for real feel that my steering axis' "activities" are best precieved when my center of mass is nearer to it than not.

Ok - new theory to support the theory I dont support.
Shorter offset - greater trail gives sinsation of more weight on front wheel with its heavier feel, allowing 10mm rearward rider position with 10mm shorter stem and dude feeling like the front is biting even though hes 10mm back.

Totally hypothetical graspin here maybe when you whack 10mm from your stem maybe need the stack height to go down 10mm? Hows that for half baked?

No bong shed guys i swear i gave that up long ago just really tired.
 
S

Sorgie

Monkey
May 20, 2005
265
80
Rochester
I came across this awhile ago when trying to figure out what stem length to get for my new build. Due to still working full time and homeschooling two kids I have not had the time to experiment with this or even build up a new bike, so I'll let you guys do it and check back.:D Maybe it's helpful, maybe not.
www.pinkbike.com

Exploring the Relationship Between Handlebar vs Stem Length - Pinkbike

We hear a lot of noise about stem lengths, but your handlebar may play the larger role in that equation.
www.pinkbike.com www.pinkbike.com
 
djjohnr

djjohnr

Turbo Monkey
Apr 21, 2002
3,104
1,795
Northern California
I think there's too many variables at play to make a blanket statement that stem length should be dependent based on X variable. On every bike I've owned the past decade I've tested stem length (5mm increments), bar height (5mm spacer increments) bar rise (~10mm increments) and more recently bar width (varying between 780 and 800), and where I've landed on each hasn't been easily correlated to any single variable like offset or reach. In testing I'm optimizing for being able to maintain balanced pressure between wheels without having to make exaggerated weight shifts while also having the right amount of room to not feel too cramped or too stretched out. If anything I'd guess stem length is more of a function of where your hands and feet are located to keep even pressure on the wheels based on the location of the bb and headtube in relation to the front and rear contact patches.
 
Muddy

Muddy

ancient crusty bog dude
Jul 7, 2013
2,032
908
Free Soda Refills at Fuddruckers
Too-short a stem and there's little to no ability to have the front end track by means of body-weight. The lessened sensation of steering arc shifts that portion of control from the part also centering the bike.
Mountain Bike is becoming dumb, seems there's less and less riding by feel and more the want to be validated by numbers/data.
On a side note - my 6POINT turns 15 y.o this year!!!
 
Gary

Gary

my pronouns are hag/gis
Aug 27, 2002
8,405
6,286
UK
Muddy said:
Too-short a stem and there's little to no ability to have the front end track by means of body-weight.
Click to expand...
How much weight you can put through the front wheel depends quite a lot on the size of the rider and the reach of the bike.
you should know this if you still ride an old skool 6 point
 
kidwoo

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
42,146
13,344
Squirtin ketchup n' mustard on charred flesh
englertracing said:
So why would one think that shorter offset, that creates more trail and slower more stable steering, would allow for a shorter stem that feels more numb??
Why would one think that longer offset, that creates less trail and quicker less stable steering, would allow for a longer stem that feels more twitchy??

Im trying to say that the theory that stem length shouldn't be less than offset "because dey shoulf match MOAR better" is at best half baked
Click to expand...
You do realize that most of us saying this have tried a very wide range of stems and fork offsets right?
 
R

Rhubarb

Monkey
Jan 11, 2009
463
238
ZHendo said:
Currently waiting on an EXT Storia to replace the stock X2

View attachment 144093
Click to expand...
Real Jelly. Picked up a used 2017 frame to use 26" parts I had (enough for a complete build) and its epic. Quick under power, jumps/corners well, and deals with the rough like a dream. If the new version is better then whooha. Ride report please.
 
englertracing

englertracing

you owe me a sandwich
Mar 5, 2012
1,649
1,137
La Verne
kidwoo said:
You do realize that most of us saying this have tried a very wide range of stems and fork offsets right?
Click to expand...
Yeah brah me too....

Including asjustable clamps on dirt and pavement on motos and supermotos.... Where increacing the "stem" length sends shit to unstable hell in a hand basket soooooo quickly reguardless of offset.

I just think the key to it isnt about matching or exceeding offset, but rather a lage pile of other shit...

In other words how do you think incracing trail "a lever aft of steering axis centerline" allows use of a shorter lever ahead of steering axis centerline?

Should they add up to a magical number perhaps?

Im genuinely asking for your theory
 
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