Bosch Gen 4 Chainring Nut printed Torque of 25 to 30 NM is likely wrong

[irie]

Thanks Irie. I think I missed your post. Are the new ones made of a different material do you think?

Look the same to me, but what do I know?

PS - I didn't fit the 'O' ring.

 

[Giff]

 

[KKe]

Any good tip, how to hold the left side crank still when torquing this nut?

 

[irie]

Any good tip, how to hold the left side crank still when torquing this nut?

Hold it with your left hand.

 

[KKe]

I think 40ish Nm with 160mm crank it’s quite hard to keep it with hand. Specially considering positioning when need to be able to torq right side without tool slipping. I don’t know, I have done this nut once before, but without torq wrench. I feel I didn’t get it very tight because wasn’t able to hold left side.

 

[shanesnr]

After following Bosch instructions (grease don't loctite) the chain ring lockring nut to 25 to 30 NM and having it fall off 3 times I was pretty annoyed and about to start looking into drilling it out and using safety wire. I even went to the local Trek Dealer and had them torque it down in case my torque wrench was to blame. Most local Trek dealers just state the Torque is 25 to 30 NM (as printed on the part) - when you call Bosch if you are lucky you will get someone who will read an outdated manual and confirm the old torque spec. However, what Bosch consumer support and most Trek folks don't know is a Technical Service Bulletin was issued by Bosch that stated the spec on the lockring is actually 40 NM to 45 NM. When my wife and I dropped both chain rings while riding on vacation, thankfully we found a local mechanic who actually cared about solving the problem and informed me of the change in torque spec - he torqued the lockrings on both our Trek Rails to 45 NM and so far after 300 miles they have not moved.

V

Imagine that been the case on the old plastic bigger ones !! I gotta be honest i think there no more effective than spacers or washers minus treads.if your chainring and crankarm can tighten up against the chainring id bet it would keep it held but id put as much torgue as the bolts that hold it on onto them,try a Yamaha locknut now thats up in the 50'snm atleast ive seen the opposite side snap the outter piece that a chainring would fit on and it was placed in a strong vice and the pedal put back on the side that gets clamped to the vice but on them there square taper so wouldnt he have been better clamping the actual crank? maybe it would spin sorry for going off topic but there was reason as a extremely tight lockring can cause alot of headache and it was just to change a 20euro casing bearing a job that ive to do but ive a better plan i hope

 

[shanesnr]

Hold it with your left hand.

Or go oldschool if motor still on the bike lean the pedal on a curb

 

[Mikerb]

same as removing a stubborn pedal...........get the non drive side pedal up against a worktop bench leg or similar.

 

[Giff]

Or try this. Carefully!

 

[Arminius]

Or try this. Carefully!

View attachment 154073

No please!
This is the simple way to do it:

same as removing a stubborn pedal...........get the non drive side pedal up against a worktop bench leg or similar.

Good to have a quality nut and fyi Bosch increased over the years the torque for tightening the lockring - think this was mentioned somewhere in this forum before.

Some men on a big island between atlantic and the north sea are able to do it with simples stones along the road!

Pic of the Day

I'm ashamed to say that we have screen protectors on our (non-smart) Kiox displays. I can feel a temporary membership ban coming on🤣

www.emtbforums.com

 

[irie]

fyi Bosch increased over the years the torque for tightening the lockring - think this was mentioned somewhere in this forum before.

Chain ring Line??

Looking to overhaul my drive line on my now 2 year old Sam 6.9. Got nearly all the components except the chain ring, looking at buying a Race Face one from Fox Australia as only one I can find but there is a section for chain line in mm's, one is 52mm and the other is 55mm's. Anyone know what...

www.emtbforums.com

""Guess what the new Bosch lockring that I just bought and installed says on it? 35 nm

Lockrings dated 11-2018 said 25-30nm

This lockring dated 10-2023 says 35nm""

 

[KKe]

No please!
This is the simple way to do it:


Good to have a quality nut and fyi Bosch increased over the years the torque for tightening the lockring - think this was mentioned somewhere in this forum before.

Some men on a big island between atlantic and the north sea are able to do it with simples stones along the road!

Pic of the Day

I'm ashamed to say that we have screen protectors on our (non-smart) Kiox displays. I can feel a temporary membership ban coming on🤣

www.emtbforums.com

Yes, probably best way is to mount wheels, take the bike down from stand for tightening.
I think part of my problem on this is shitty parktool bbt 18 tool. It doesn’t accept 1/2 inch driver and is weirdo 8 sided(this must be designed by somebody who never seen any tool before)interface that means ring spanner doesn’t fit also. With open end wrench it’s not very convenient to turn it to 35nm with one hand .