Short stem or long stem?

[cabbynate]

So the Jam2 came with a 55mm stem. When I changed the bars I decided to go with a 35mm stem as they seem to be all the rage. I am going back to the 55mm stem as my knees seem to close to the bars. Broke the cheap top cap that cam on the Focus so waiting for a replacement. This one will be Aluminum. Anyone else try a different length on there Focus Jam2?

 

[StevenM]

It’s not just bike length, it about weight ballance

 

[Gary]

It’s not just bike length, it about weight ballance

and handling (steering response)

It's just personal preference. Neither length is wrong. (having said that I wouldn't go much longer than 55m(or shorter than 35mm)

If you're genuinely hitting your knees off the bars on any bike you've either bought far far too small a bike, Set it up really realy badly or you really need to look at your riding technique.

 

[simtee]

I am currently riding with 70mm stem on my Jam2. Stock 55mm made bike feel a bit short so I took 70mm version which I already had from my previous projects. Bike feels good, although 60mm or 65mm could be optimal for my type of driving. Longer stem makes steering a bit slower and makes it easier to put weight on front wheel. Pedalling position feels also more efficient with longer stem.

 

[GrandPaBrogan]

There's a lot of different factors that determine the correct stem length. Gotta look at it from a wholistic view... and treat any blanket statement about whatever bike set-up - with a 'grain of salt.'

Speaking of which, I'll give you a blanket statement of my own...
The right stem length for you - is the length that allows you to stop thinking about your stem length during your ride.

Same goes for everything... bar width, bar height, grips, pedals...

See what I did there? I just answered your question without giving you an answer.

 

[Mikerb]

stem length is not about fashion, it is a bout achieving a comfortable well balanced position on the bike...... and 20mm is a big step to change stem length in one go. Both the position of the saddle on its rails and the length/rise of the stem....and rise/sweep/width of the bars can have a big impact on your weight distribution both in the seated position and in the attack position. You need a stem length/rise that balances your weight in both positions. Personally I would be less concerned about seated pedalling position ( e.g. as per a road bike)…..most of the time I have my dropper partly down between heads of trails anyway, so not worried a bout peddling efficiency.

 

[cabbynate]

stem length is not about fashion, it is a bout achieving a comfortable well balanced position on the bike...... and 20mm is a big step to change stem length in one go. Both the position of the saddle on its rails and the length/rise of the stem....and rise/sweep/width of the bars can have a big impact on your weight distribution both in the seated position and in the attack position. You need a stem length/rise that balances your weight in both positions. Personally I would be less concerned about seated pedalling position ( e.g. as per a road bike)…..most of the time I have my dropper partly down between heads of trails anyway, so not worried a bout peddling efficiency.

The 55mm stem was the stem that came on the bike. It also had 0mm rise 760 bars. I went up 20mm rise on the bars and went down 20mm on the stem as noted. What I noticed is the front end got a lot lighter and that made the bike more lively. Steep climbs were a bit of a challenge but I never looped out. I'm wanting a little more wight on the front end without taking to much of the liveliness out of what I put in. A 45mm stem may be what I settle on. The 55mm is what I had laying around so it is what I used. I do a lot of single track trail riding with a lot of climbing. Really rocky, silky dirt with hard packed underneath. Lots of G outs. Lots of big slab slick jagged rock too. What goes up must come down so the down hill stuff can be a bit sketchy at times and I don't jump nearly as much as I would like. Still I am trying to get that balance so when I need to manual I can get it up without to much difficulty. In stock form the bike was a bit front heavy, with the wide riser bars and short stem a tad bit to lite so just looking for that sweet spot in balanced position on the bike.

 

[mark.ai]

This is a useful read if your bars have any kind of sweep and you're interested in how that can interact with stem length:

Exploring the Relationship Between Handlebar vs Stem Length - Pinkbike

 

[Mikerb]

...or just modify your climbing technique.

 

[Mikerb]

This is a useful read if your bars have any kind of sweep and you're interested in how that can interact with stem length:

Exploring the Relationship Between Handlebar vs Stem Length - Pinkbike

Fascinating. The focus in that article seems to be mostly about steering stability however whilst the OP is concerned about weight balance over the front wheel. Looks like care needs to be taken though as per that article, that you dont mess up the steering stability in the process!

 

[GrandPaBrogan]

Fascinating. The focus in that article seems to be mostly about steering stability however whilst the OP is concerned about weight balance over the front wheel. Looks like care needs to be taken though as per that article, that you dont mess up the steering stability in the process!

I agree. Unfortunately the real crux of the matter in some cases is the stem length needs to be adjusted to compensate incorrect frame sizing - which may or may not be at the expense of steering stability.

@cabbynate why are you freaking out that your stem is a 55mm? World Enduro champion Sam Hill uses a 55mm stem last time I looked. You can be sure he didn’t choose that because he’s following a fad.

 

[cabbynate]

Fascinating. The focus in that article seems to be mostly about steering stability however whilst the OP is concerned about weight balance over the front wheel. Looks like care needs to be taken though as per that article, that you don't mess up the steering stability in the process!

I think that's what I did when I went with the 35mm stem. my bars are 9 degree back sweep so by the article I had about a 15mm effective stem length.

 

[cabbynate]

I agree. Unfortunately the real crux of the matter in some cases is the stem length needs to be adjusted to compensate incorrect frame sizing - which may or may not be at the expense of steering stability.

@cabbynate why are you freaking out that your stem is a 55mm? World Enduro champion Sam Hill uses a 55mm stem last time I looked. You can be sure he didn’t choose that because he’s following a fad.

I'm not freaking out. Just trying to get a balance.

 

[GrandPaBrogan]

I'm not freaking out. Just trying to get a balance.

Sorry mate... poor choice of words on my part.

 

[Chubba]

and handling (steering response)
If you're genuinely hitting your knees off the bars on any bike you've either bought far far too small a bike, Set it up really realy badly or you really need to look at your riding technique.

This sounds like the problem to me - I can't understand how a 2cm difference would have you knocking your knees on the bars.

 

[cabbynate]

This sounds like the problem to me - I can't understand how a 2cm difference would have you knocking your knees on the bars.

My knees were not hitting the bars. I never said that. The cockpit was a bit more cramped than I liked. Going back to the 55mm stem has given me a bit more room on the short test ride I took. I won't know the extent of the change until I get the bike on the trail.

 

[Chubba]

My knees were not hitting the bars. I never said that. The cockpit was a bit more cramped than I liked. Going back to the 55mm stem has given me a bit more room on the short test ride I took. I won't know the extent of the change until I get the bike on the trail.

Apologies for that. I'm riding 55.

 

[cabbynate]

This is a useful read if your bars have any kind of sweep and you're interested in how that can interact with stem length:

Exploring the Relationship Between Handlebar vs Stem Length - Pinkbike

I found this article very interesting. I do question if being an ebike would make a difference though. We have more power on tap most of the time so just wondering if that could make a difference too mainly when climbing...

 

[iainc]

The 2019 Jam is quite a short bike...the 2020 ones are significantly longer effective top tube and reach

 

[simtee]

The 2019 Jam is quite a short bike...the 2020 ones are significantly longer effective top tube and reach

Are they actually longer? 2020 Shimano equipped Jam2 geometry seems to be identical to 2019 versions. 2020 Bosch versions have shorter effective top tube and wheelbase but longer reach when compared to 2019 models. Go figure?

 

[iainc]

Yeah, the frames on the shimano ones are unchanged, the Bosch 2020 ones are longer, lower, slacker, overall though your point re ETT is bang on.

 

[comtn]

If you need to change the stem length you bought the wrong size frame. The stem length and slackness are tied together. If you shorted the stem you speed up the steering. Lengthen it and you slow down the steering. The reason the '19 levo has a shorter stem vs the '18 is the frame is designed differently to accommodate a shorter stem. There is more reach built into the new frame and slackness.

 

[cabbynate]

If you need to change the stem length you bought the wrong size frame. The stem length and slackness are tied together. If you shorted the stem you speed up the steering. Lengthen it and you slow down the steering. The reason the '19 levo has a shorter stem vs the '18 is the frame is designed differently to accommodate a shorter stem. There is more reach built into the new frame and slackness.

I would have to agree with you as I went back to the stem the bike came with. Seems the 2019's had that same length too.. I am sticking with the 20mm riser 800mm bars. I didn't like the feel of the flat bars.

 

[simtee]

If you need to change the stem length you bought the wrong size frame. The stem length and slackness are tied together. If you shorted the stem you speed up the steering. Lengthen it and you slow down the steering. The reason the '19 levo has a shorter stem vs the '18 is the frame is designed differently to accommodate a shorter stem. There is more reach built into the new frame and slackness.

This is true, everything on bike's front end has effect to handling, e.g. slackness, stem length&angle, handlebar rise&width&sweep and so on. However, I see that it is completely ok to change those elements a bit to get bike feel better for you. Setup from bike factory is typically not exact match for your exact body dimensions/riding style, so subtle changes in e.g. stem or handlebar are usually beneficial. I would not of course put e.g. over 100mm stem to Jam2, that would probably make steering too slow and cause also other unwanted things...

 

[S D]

I would have to agree with you as I went back to the stem the bike came with. Seems the 2019's had that same length too.. I am sticking with the 20mm riser 800mm bars. I didn't like the feel of the flat bars.

I went through the the same thing , eventually
I put the original stem back on but went with risers as I could not get on with the flat bars.
One thing not previously mentioned (unless I missed it)
Where did you guys end up with the stem spacers when you fitted risers?

 

[cabbynate]

This is true, everything on bike's front end has effect to handling, e.g. slackness, stem length&angle, handlebar rise&width&sweep and so on. However, I see that it is completely ok to change those elements a bit to get bike feel better for you. Setup from bike factory is typically not exact match for your exact body dimensions/riding style, so subtle changes in e.g. stem or handlebar are usually beneficial. I would not of course put e.g. over 100mm stem to Jam2, that would probably make steering too slow and cause also other unwanted things...

I agree. I went on a proper ride today where I got to try just about everything that I do on a mountain bike and I will say the factory length stem turned out to be spot on with the wider bars and the 20 millimeter rise. I was able to climb better, jump better and Corner better. I'm 5'8/178cm and my bike is a medium so I'm pretty sure it's the right size. You are definitely correct about the staring as with the factory stem on it is way less Twitchy and much more stable. Overall the bike was much more enjoyable to ride in this configuration.

 

[simtee]

Hmm, this does not seem to match "I'm 5'8/178cm" . Anyhow, you are right, M size should be ok whether you are 173 or 178cm

 

[Mcharza]

This is true, everything on bike's front end has effect to handling, e.g. slackness, stem length&angle, handlebar rise&width&sweep and so on. However, I see that it is completely ok to change those elements a bit to get bike feel better for you. Setup from bike factory is typically not exact match for your exact body dimensions/riding style, so subtle changes in e.g. stem or handlebar are usually beneficial. I would not of course put e.g. over 100mm stem to Jam2, that would probably make steering too slow and cause also other unwanted things...

Add to that HA and fork rake (offset), that effect to handling via trail (how much is the tire contact point to the ground)

 

[cabbynate]

I went through the the same thing , eventually
I put the original stem back on but went with risers as I could not get on with the flat bars.
One thing not previously mentioned (unless I missed it)
Where did you guys end up with the stem spacers when you fitted risers?

I went with all risers below the stem but I may try one of the thinner ones on top as the 20mm rise along with the 55mm stem feel a bit high. I like the way it is but just thinking it might be a bit better dropping the stem just a few mm.

 

[GrandPaBrogan]

I went with all risers below the stem but I may try one of the thinner ones on top as the 20mm rise along with the 55mm stem feel a bit high. I like the way it is but just thinking it might be a bit berrer.

Always leave the thinnest spacer on top of the stem. You want to make sure that the entire stem clamping portion is gripping the steerer tube... especially with today’s modern stem designs where the steerer clamping area isn’t very high.