Stem with no knurling - is this ridable?

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9/29/2016 1:04 PM

I'm not sure if all stems have knurling where they clamp the handlebars, I know there's no knurling at all where the stem clamps the steer tube and it obviously bites just fine, but I know some stems (maybe all, I'm not sure) have knurling where they meet the bars. I've got a new(to me) stem where there's virtually no knurling, and the bars I have do have a ton of knurling, so I'm tempted to just think it's fine and go for it but I figured I'd check here first, because bars slipping is pretty frickin' dangerous! Thanks!!

(doubt it matters, but it's a Fit top-load that'd be holding vultus bars, so their knurling is crmo and stem is aluminum, if that matters!)

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9/29/2016 1:10 PM

I think you'll be ok. Tighten up in a diagonal sequence to get even pressure distribution. I.e. top left, bottom right, top right bottom left and repeat until all are suitable tight. I my experience you get more knurling on the bars than the stems. I've also suffered from slipping bars in the past. It's not so bad. If they do slip, it might be by an inch or so. It's not like they'll suddenly lose bite and flop down leaving you to break your face on the stem.

Fit it all up and then do some moderate riding to get a sense of how it feels. Don't go straight into heavy stuff. Get a sense for how solid and together they feel before you go trying stuff that's likely to put more pressure on the joint.

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9/29/2016 1:16 PM
Edited Date/Time: 9/29/2016 1:16 PM

maybe rough it up with some sandpaper. ride it like a boss till' your bars fly forward and your teeth are gone

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Refs: Future FBM, Warchol2 WtfKennethXp Riversiderider TCbmx Riversiderider JakeSalbert

9/29/2016 1:20 PM

No stems have a gnurled surface. Just tighten it properly. The recommended torque is around about 12Nm for stem bolts, they don't have to be silly tight, you won't need to use an extension bar for leverage but as tight as you can (without excessive force) with an average length Allen key is plenty. As above, tighten in an X pattern keeping an eye on the gap between the top plate and the rest of the stem making sure it's equal so the load is spread evenly across all 4 bolts

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9/29/2016 1:21 PM

It's normal. Typically the handlebars are what have the knurling, not the stem. The grooves on the bars will dig into the stem and make it look like they have knurling overtime though

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9/29/2016 2:23 PM

Oh and another thing I'm unsure on is whether or not I can use a small spacer to raise the stem's height - I cut my steerer tube to fit my current stem (which has a 2mm taller stack height than this Fit one does), so I don't have a lot of space to work with - I guess I'm wondering just what "minimal %" of the stem needs to be in contact with the steerer tube, obviously 100% is ideal (well, 99.9%, so your compression bolt can still work) and 50% seems quite dangerous, am hoping to find the lowest % I can do before it being a dumb idea! (I have multiple spacer sizes, for instance a 9mm spacer would make it so that only 66% of the stem's stack height is in contact with the steer tube - I'm pretty damn sure that's not safe, but what about 75%? 85%? Am just looking for opinions on the lowest % you'd ride without being afraid of it!)

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9/29/2016 2:27 PM
Edited Date/Time: 9/29/2016 2:30 PM

sundaybmxRR wrote:

It's normal. Typically the handlebars are what have the knurling, not the stem. The grooves on the bars will dig into the stem ...more

HELL YEAH! I was really hoping to hear this, I've spent a lot of time re-finishing this stem and really love its height::reach dimensions relative to my stem (ody lincoln) so wanted it to work! I made another post while you may've been writing that one, do you have any thoughts on minimal stack-height? My steer-tube is cut to like 31mm for my current 32mm stack-height stem, this new stem is like a mm or two shorter than the old one so it's going to be pretty flush already, but would love to throw a spacer in there for some rise since I'm riding shorter bars (an experiment, probably temporary) and just don't know if it's safe or not, and if it is ok then just how little of the stem needs to make contact, like 85% minimum? 75%?


[Edit: FWIW, I swear that if I end up eating shit because of something related to this, I will post it lol!]

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9/29/2016 2:34 PM

grumpySteve wrote:

No stems have a gnurled surface. Just tighten it properly. The recommended torque is around about 12Nm for stem bolts, they ...more

Ok I have two ody lincoln stems and I would've sworn they had knurling, but they're both 2nd-hand so it's gotta be bar imprints! Thanks for the installation tips, I always do the X pattern but had forgotten about checking height to make sure the gap is even (for the sake of grip *and* the threads!), am pretty psyched because honestly I've been having reservations about my stem, the lincoln is an awesome stem but it's only got two bolts biting the bar, and I get that the hinges are the 'other bolts' but it's always bugged me a bit and have wanted a proper, 4-bolt, top-load stem - very happy to have gotten this guy for $10!

(I got one lincoln on a used bike, another was for practically nothing because the wedge's bolt was stripped, so they fell into my hands I never sought them or would seek anything besides 4-bolt, top-load stems!)

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9/29/2016 2:38 PM

Spenlard wrote:

maybe rough it up with some sandpaper. ride it like a boss till' your bars fly forward and your teeth are gone

That had crossed my mind, but was afraid that, in the act of sanding, you'd reduce surface area, and that the increased grittiness of the surface may not compensate for the loss in total contact area, I dunno.. Anyone else second this idea of sanding it? Obviously would sand left-to-right ie perpendicular to the way the bars would want to move, and I have 80-400g (and steel wools that're ~1k grit, and 3k grit), would definitely like to sand it if that's advised!

(no offence Spenlard, just want other opinions as my bars moving in the stem is definitely my biggest equipment-failure fear!)

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9/29/2016 2:41 PM

Stevearcade wrote:

I think you'll be ok. Tighten up in a diagonal sequence to get even pressure distribution. I.e. top left, bottom right, top ...more

Damn I've had the exact opposite experiences, and am having trouble picturing how they *wouldn't* whip out of control! I mean, once the bite is lost and they're sliding, they go ALL THE WAY (in every instance I can remember where this has happened to me! Every time I can remember bars slipping on me, they slipped all the way and it was always an ugly fall)

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9/29/2016 2:44 PM

Stevearcade wrote:

I think you'll be ok. Tighten up in a diagonal sequence to get even pressure distribution. I.e. top left, bottom right, top ...more

adfkje wrote:

Damn I've had the exact opposite experiences, and am having trouble picturing how they *wouldn't* whip out of control! I mean, ...more

Ouch! I must not have been riding hard enough, felt a slip and was able to sort it before they moved more. I can only imaging a full loss of grip and bars swinging down instantly. That must have really hurt!

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9/29/2016 3:39 PM
Edited Date/Time: 9/29/2016 3:41 PM

Stevearcade wrote:

Ouch! I must not have been riding hard enough, felt a slip and was able to sort it before they moved more. I can only imaging ...more

Oh man I put a pair of bars in a few weeks back, didn't think the slight bump on the knurling would be an issue, and when I started pedalling hard (a block from my house) they just flopped right down! I should've stress-tested them by hand before going riding, was a dumb move lol but yeah I've had a pair slip on me before that were fine for a long, long time and I was just landing something real small maybe even as small as a curb and I must've had my weight all on my bars because I threw them forward! That really sucked, will always be wary of stems and ever since that I still routinely tighten my stem at least once every week or two just to be sure it's tight! (edit- it's funny because, most-every time that I do this, I get a *slight* bit of turn, so I don't know if they'd just keep getting looser or if they just get a little looser and stay there, but yeah I'm always re-tightening my stem so am psyched to have 4 bolts to clamp down instead of just two!

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9/29/2016 5:05 PM
Edited Date/Time: 9/29/2016 5:49 PM

Stevearcade wrote:

Ouch! I must not have been riding hard enough, felt a slip and was able to sort it before they moved more. I can only imaging ...more

this is so unbelievable that I hesitate to post it but will anyways - it literally just happened to me!! I went for a very quick ride with my brother, went to a spot and had a couple ugly misses/bails (and a bloody shin lol), but it must've happened when the bike hit the ground because we stayed there maybe 5min while I tried to stick it (the spot is a PITA because it's real short so on/off real fast), I didn't notice when it happened, didn't notice on the ride home, and I get inside and saw my bike from the side and it's gotta be off about an inch!! i cannot believe that just happened, both the coincidence and the movement as I have that setup incredibly well&tight

(to be clear I think i'm pretty sure it wasn't *me* but the ground or hte ledge hitting my bike when I bailed, they're moved inwards towards me not away from the bike, they even break parallel with the forks)
((double-edit: this is NOT the stem in question, that's still being finished this happened with my stem that's NEVER done this before with these bars or any bars except 1 pair that had bad knurling))

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9/29/2016 5:30 PM

adfkje wrote:

HELL YEAH! I was really hoping to hear this, I've spent a lot of time re-finishing this stem and really love its height::reach ...more

do you mean how far above the top of the stem should sit above the top of the steerer tube? no more than 5 or 6mm, and no less than 2 or 3 is my rule. You need that little bit of space in between other wise when you tighten up, the bolt will just bottom out on the steerer tube when things pull together tighter

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9/29/2016 11:53 PM

adfkje wrote:

this is so unbelievable that I hesitate to post it but will anyways - it literally just happened to me!! I went for a very ...more

Haha! What are the odds... I had a set of bars years ago that would migrate like this. I'd notice after a ride from time to time that they'd slipped like this. In fact, the knurled bit of the bar actually started to wear smooth from the movement, which actually made the matter worse causing it to happen more frequently. A nasty self perpetuating problem.

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9/30/2016 1:35 AM

I wouldn't . Get a razor blade and cut diagonal lines in the bars and before that sand it up too . It'd be on my mind before going big , I wouldn't be able to ride them LOL

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9/30/2016 6:28 AM

Stevearcade wrote:

Haha! What are the odds... I had a set of bars years ago that would migrate like this. I'd notice after a ride from time to ...more

Yeah I know what you mean, I'd constantly move my bars when I was trying to learn just where my ideal grip spot was, so was constantly clamping the shit out of it in spots very close to one another - when the stem is just-loose-enough to allow the bars to move to adjust them, you can feel it giving more resistance ie the knurling isn't a perfect circle anymore, it's indented wherever your stem's gap was.

And yeah the odds are ridiculous I mean it happens within an hour (maybe half hour) of posting, like voodoo! It turned out that my stem is bottoming-out again, although last time the bars never slipped I just noticed they were pinching and used a sanding-wheel to shave a mm of metal off (it's the odyssey lincoln stem, so the faceplate is hinged in the back and takes two bolts up front - where those bolts come together, the metal began pinching, presumably from me stretching that hinge over time, until finally the metal was touching! And now it's touching again, will have to sand it but with the hinges being that stretched I'm about to relegate it to my parts-bin!)

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9/30/2016 6:31 AM
Edited Date/Time: 9/30/2016 6:33 AM

Brayden_Buckingham wrote:

I wouldn't . Get a razor blade and cut diagonal lines in the bars and before that sand it up too . It'd be on my mind before ...more

You seem to misunderstand what the problem is (probably because I suck at conveying things sometimes) but it's *not* the bars, all 3 sets of bars I own have excellent knurling, the problem (what I thought was a problem) was the lack of knurling inside the stem, but as others have said that is not a spot where I should be expecting knurling ergo the stem is fine (in that regard at least)

That said, it's got me thinking about buying "Carbon Assembly Gel", I'm unsure if anyone here ever uses it but I think the bars//stem area would be a good spot to use some!

[edit: Oh and I do plan to sand the stem where it touches the bars, am planning to use a 100grit, sanding perpendicular to the bike so the sanding 'grooves' are against where the bars want to spin]

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9/30/2016 6:53 AM

This has probably been touched upon up there, but I'm throwing my 2cents into the equation.

Sanding will help. It wont reduce contact area of whatever-it will increase the friction coefficient by giving a rougher surface to mate onto.

I had problems too, altho my bars and stem where knurled. Here's what you could do:

-Start by sanding as you propose, perpendicular to the bike.

-Loosen a few grains of sand, then tighten your bars into your stem. Use a rubber-coated hammer and knock the bars from side to side (side to side as in perpendicular to the bike).

-Scratch in a few X/diagonal lines with a scalpel/knife. Being aluminium, it should be easy.

-Clean the interface area REALLY well. Use soap. But get it clean as hell.

-That should do. If not, you can always put in some loctite in there to get things nicely stuck.

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9/30/2016 11:14 AM

adfkje wrote:

I'm not sure if all stems have knurling where they clamp the handlebars, I know there's no knurling at all where the stem ...more

Take the ano/paint out with sandpaper, and CAREFULLY, while pulling AWAY FROM YOURSELF, carve grooves the length of the clamp area with a box cutter.

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9/30/2016 6:05 PM

Skylight wrote:

This has probably been touched upon up there, but I'm throwing my 2cents into the equation.

Sanding will help. It wont reduce ...more

am glad you threw your change in, thank you smile

So your stem was knurled- what stem is it?

The grains-of-sand thing, is that your idea or did you learn it? I find it intriguing but I'm afraid it could work against the purpose here, if for no reason other than the fact that you'd need homogeneously-sized grit to do it properly (otherwise the strongest groove would prevail right? Or does it not matter, because it's not the recesses, but the metal that was pushed out during their carving, that does the biting?)

Scratching lines- why diagonal? I would have thought perpendicular..

Cleaning- oh yeah, I'm a nut when it comes to metal-on-metal lol,anytime I do anything on my bike, better believe the threads&surfaces are all cleaned and re-lubed or, in the case of clamping, are cleaned with isopropyl alcohol!!

Loctite- lol I couldn't even imagine! It's not a bad idea really, sounds like it'd help - have you heard of "Carbon assembly gel"? It seems to be a carbon grit (suspended in some kind of evaporating solution maybe alcohol) that's used by car mechanics for metal-on-metal 'bite', have been wanting to go find it for a while I think it'd find perfect application here, seat-posts, etc any spot where it's metal clamping on metal instead of bolting-into it.

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9/30/2016 6:07 PM

dave lawrence wrote:

Take the ano/paint out with sandpaper, and CAREFULLY, while pulling AWAY FROM YOURSELF, carve grooves the length of the clamp ...more

Thanks for that! Can anyone else vouch for this? It's been reco'd twice in this thread, to just carve grooves in the stem - it sounds like a good idea on one level but I've just never heard it and am hesitant to try anything i'm unsure of, not for the bar::stem intersection it's just too dangerous if it fails!

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