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New Boxxer coming loose leading to headset knock?

6thElement

Schrodinger's Immigrant
Jul 29, 2008
9,113
5,962
I keep having issues with the Boxxer on my new this year Commencal Supreme.

I've tried with the crowns tightened to the recommended torque printed on them. I've tried a tiny bit tighter.

But every couple of trips to the bike park I'm having to loosen the top crown, give the headset preload an extra little turn and then tighten it back up.

Any thoughts, recommendations, try it now with g-tape?
 

carlos1

Chimp
Nov 14, 2011
42
31
Czech Republic
ZS56 top and bottom I think.
Hi, I have the same frame, but fox 40, same issue. The problem is shitty acros headset(the lower cone that is pressed on the steer tube), the lover cone is made from some butter aluminium, so you have to replace it, or change the lover headset cup for some that has a steel lower cone, that helped me, and I wouldnt use the starnut to tighten the headset, but use this: http://www.foxholeshop.cz/utahovak-hlavoveho-slozeni-box-one-stem-lock-1-5--tapered/ , sorry its from czech shop, but you get the idea what you need. If you need any detail, just sen a message. Cheers
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
9,113
5,962
Hi, I have the same frame, but fox 40, same issue. The problem is shitty acros headset(the lower cone that is pressed on the steer tube), the lover cone is made from some butter aluminium, so you have to replace it, or change the lover headset cup for some that has a steel lower cone, that helped me, and I wouldnt use the starnut to tighten the headset, but use this: http://www.foxholeshop.cz/utahovak-hlavoveho-slozeni-box-one-stem-lock-1-5--tapered/ , sorry its from czech shop, but you get the idea what you need. If you need any detail, just sen a message. Cheers
Just got around to dropping the fork and checking and I agree. The crown race is made from soft cheese. It's now pitted along the front edge.

The Acros website doesn't list bearing dimensions either so I guess I need to hope the bearing has some useful markings. I was hoping I might be able to use another crown race from my parts.

 

carlos1

Chimp
Nov 14, 2011
42
31
Czech Republic
Just got around to dropping the fork and checking and I agree. The crown race is made from soft cheese. It's now pitted along the front edge.

The Acros website doesn't list bearing dimensions either so I guess I need to hope the bearing has some useful markings. I was hoping I might be able to use another crown race from my parts.

You cant change the bearings, they are pressed in the cups, but the bearings are ok, you can buy the crown race, its cheap, but the postage is nearly the same amount as the race :( , if you have anothe crown from different headset, try it out, the bearing have standard 45 taper, but the diameter is slightly smaller, than the standard bearings, just try it out. Commencal probablly had issues with this headset, they now have Cane Creek headset, whitch should be better(has steel crown) , https://www.commencal-store.co.uk/cane-creek-40-series-headset-zs56-zs56-for-supreme-dh-c2x32567977
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
9,113
5,962
You cant change the bearings, they are pressed in the cups, but the bearings are ok, you can buy the crown race, its cheap, but the postage is nearly the same amount as the race :( , if you have anothe crown from different headset, try it out, the bearing have standard 45 taper, but the diameter is slightly smaller, than the standard bearings, just try it out. Commencal probablly had issues with this headset, they now have Cane Creek headset, whitch should be better(has steel crown) , https://www.commencal-store.co.uk/cane-creek-40-series-headset-zs56-zs56-for-supreme-dh-c2x32567977
Thanks for the tip on the bearings being pressed in the cups. I had wondered why the bearing wasn't dropping out of the lower cup and hadn't resorted to hitting it yet.

edit:
Thankfully I live a few minutes away from their US HQ, dropping the bike off shortly and they'll fit a new crown race. We'll see if this one can hold together with everything clamped to spec.
 
Last edited:

carlos1

Chimp
Nov 14, 2011
42
31
Czech Republic
Thanks for the tip on the bearings being pressed in the cups. I had wondered why the bearing wasn't dropping out of the lower cup and hadn't resorted to hitting it yet.

edit:
Thankfully I live a few minutes away from their US HQ, dropping the bike off shortly and they'll fit a new crown race. We'll see if this one can hold together with everything clamped to spec.
I am on second crown race, same stuff, so I made myself adaptors from 7075 AL to fit in the head tube and I can use standard non tapered Headset with steel crown race, will see if it holds up
 

6thElement

Schrodinger's Immigrant
Jul 29, 2008
9,113
5,962
I am on second crown race, same stuff, so I made myself adaptors from 7075 AL to fit in the head tube and I can use standard non tapered Headset with steel crown race, will see if it holds up
Can you post some pictures?

My wife just got the exact same bike with same headset, so I can see if hers has the same issue.

If it does happen again and Commencal can't fix, my first attempt will be see if the cane creek steel crown race will fit, if not, I'll fit a CC lower headset with that steel crown race and maybe the Box stem lock.
 

buckoW

Turbo Monkey
Mar 1, 2007
2,182
1,379
Champery, Switzerland
Get a couple races so you can replace them when needed. I have to replace those way more often than I would like on our DH bikes.
The lower race gets a ring worn into them sometimes.