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Discussion Starter · #1 ·
My mtb cockpit has some components from 2013 which I plan to upgrade this summer. The components were all upper mid quality when new. I recently purchased a custom headset cap from kustomcaps.com. I also purchased the following torque wrench:

https://www.jensonusa.com/Shimano-Pro-Torque-Wrench

I rode the bike for years without any cockpit issues but I've been having issues ever since I unmounted the handlebar myself for the first time about a month ago.

My headset is not keeping the front wheel straight. For example, if I do a quick, sharp turn of the handlebar left and back to center, then this throws the wheel out of alignment. I can reproduce this consistently and throw the wheel totally out of alignment.

I tried different settings on the torque wrench, even up to the15nm max setting but I still experience the behavior above. Since the torque wrench is designed for mtb, I'm guessing that I could potentially strip the threads/bolts if I attempt to tighten with much more force.

I was thinking that maybe some type of rubber washer would probably help prevent the slippage that I'm currently experiencing. I don't think that there was originally a rubber washer under the headset cap but maybe there was and I just wasn't paying attention?

Is there any particular type of rubber washer that you recommend for this? Or do you suspect that some other aspect is awry?
 

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Don't Tread on Me
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It sounds like you are describing a loose stem on the steerer. Are you tightening the wrong bolts? Are you tightening the handlebar clamp bolts when you should be tightening the stem to steerer bolts? You may be in over your head. I would have someone safety check your work before you ride.
 

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Sneaker man
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When you say you "unmounted the handlebar" do you mean you took the handlebar off the stem (unbolted the face of the stem and took the bar off) or unbolted the stem from the fork steerer and took the handlebar and stem away from the frame? Did the new top cap get put on at this time?
As said, definately sounds like the stem bolts arenot tightend enough. Coul dbe the torque wrench is wrong/stuffed/used incorrectly (have never used a torque wrench in 30 years riding, so no idea how they work).
Could also be the top cap, does not fit and is somehow messing things up...maybe...
 

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Tightening the stem top cap is not supposed to keep your handlebars and wheel aligned. The top cap bolt is tightened to draw the fork's steerer tube up tight in the headset bearings.

You tighten this bolt snug until you have no slop, and then you tighten the stem (to steerer tube) bolts to a) lock in the tension that you set with the stem top cap bolt and b) lock in the alignment of your handlebars and front wheel. Once the stem bolts are correctly torqued you should be able to back off the top cap bolt without negative repurcussions.

You may want to remove the stem from the steerer tube and clean (alcohol on a rag) the mating surfaces of the stem and steerer tube, and reassemble, using the correct torque on the stem bolts. Once you think both bolts are torqued, torque them both one more time (i.e. when you think bolt 1 is sufficiently snug, you then snug up bolt 2...but if you go back to bolt 1, it now isn't as snug as before you snugged bolt 2 because bolt 2 took some of the tension when you snugged it), so snug bolt 1 again.and then bolt 2, too).
 

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OP, just seeking clarification:

You bought a custom stem cap, which you call a headset cap?

After installing, your headset feels loose and wheel is bouncy hard to keep a line?

When you installed new stem cap did you loosen the stem neck bolts? These are the bolts that clamp around the fork's steerer tube?

Need to loosen the neck bolts before installing new stem cap. The order is critical. Install stem cap then tighten neck bolts. Make sure headset upper is pushed down all the way when doing this.

If you do it correctly and still have problems, then compare the underside of your new stem cap to the old one. If the new one protrudes down more it may make contact with steerer tube when you tighten bolt. If so, you will need to remove a stem spacer. Also, if new stem cap is plastic and you overtighten stem cap bolt, then you can crack the stem cap. If you crack it, then it is history, use old one.

Sent from my moto x4 using Tapatalk
 

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This bike needs to be taken to a shop.
Too confusing about what has been loosened.
If the stem bolts have been loosened, OP needs to have a shop properly set the preload for them. While there, ask how they determine how tight is too tight. Then next time OP chooses to work on the front end they will have an idea of how much to tighten a top cap.

IF the top cap has been tightened to 15nm, there is risk of damaging bearings/races.

Not to mention that OP can probably crash hard when hitting a rock and the bars turn while bike tries to go straight. Egads!
 

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Discussion Starter · #10 ·
the problem was that the side bolts were loose. lbs guy told me to just use 5nm all around going forward. my lbs guy mentioned that the sequence of tightening was important. specifically, the top bolt should be tightened before the side bolts.

is it generally safe to remove and replace the top bolt without removing and replacing the side bolts? not sure if this could ever potentially create an alignment issue?
 

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If you loosened the side/neck bolts then yes, enitrely possible your bars were moved out of alignment, not a big deal. Loosen stem and side bolts and re-align, then tighten stem bolt, then side bolts.

This is a lot easier than it sounds but it also has some touch/finesse involved. If you mistakenly bump the bars while trying to tighten you can bump the alignment, start over. If you are an extreme perfectionist it may take a while to get it perfectly aligned.

Take your time and follow the sequence and you should be good to go.

This is one routine where beer helps.

Sent from my moto x4 using Tapatalk
 

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high pivot witchcraft
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Take it to a shop. Clearly you have no idea what you are doing. Not to sound melodramatic but the risk of your bar/wheel twisting in the midst of blasting a down or when landing after getting some air could be catastrophic.
 

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Single(Pivot)and Happy
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^^^^^ Please take mtnbkrmike's advice to take your bike to a bike shop with competent mechanics. There's nothing wrong with not having the knowledge to perform maintenance on your bike. I believe you have some idea of what you are doing but not enough to properly perform this task. As mtnbkrmike states failure to complete this task properly will result in the loss of control. Depending on other variables will determine the extent of injuries you will receive. Damage to your bike, specifically deformation of your head tube, which will render your frame unrideable, is a real possibility.
 

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At least try to do it yourself and then take it to a shop to have your work checked. I believe in you.

This basic task can be a mystery because we may not understand the "why. ". Ask the shop to explain the why for each step.



Sent from my moto x4 using Tapatalk
 

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Stem bolts cant take 15nm of torque, so its kinda scary you torqued something to 15nm.
Yup. I'm with the folks who are saying to just take it to a shop.

I never tighten cockpit bolts more than 5Nm. 15 is scary, and qualified mechanics need to go over this and make sure something didn't get damaged to the point that it's now unsafe.
 

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Learning is well and good.

Two things to learn the hard way here:
1) too much or too little torque on the side bolts will break a bolt or not hold stem securely
2) too much or too little preload on the bearings will ruin bearings requiring the expense of bearing replacement.

Or like one mentioned: do the work then have a shop check your work.

OP, you recent quest was rather or not the cap can be removed/replaced without loosening the side bolts. The answer is yes.

First set bearing preload then tighten side bolts. From here on the headset "shouldn't" loosen from just replacing the top cap.
 
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