Locking chain wheel nut

[aerodiamond]

Has anyone found a way of locking the castelated chainring nut on bosch gen 4 drive units. Locktite last about six months. I thought of drilling the nut and wire locking but there's not much metal to drill into. Any ideas

Nigel

 

[irie]

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

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...

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[The EMF]

I torque the nut to 40 ft/lbs. The same torque setting as the cassette lock nut.
Never had one come loose. Apply a touch of “ Copper Slip” anti-seize to the male thread to prevent the thread from picking up.

 

[irie]

I torque the nut to 40 ft/lbs. The same torque setting as the cassette lock nut.
Never had one come loose. Apply a touch of “ Copper Slip” anti-seize to the male thread to prevent the thread from picking up.

Correct me if I'm wrong, but 40 ft/lb is about 54 Nm! Isn't the cassette lock nut about 40Nm?

 

[Bndit]

Has anyone found a way of locking the castelated chainring nut on bosch gen 4 drive units. Locktite last about six months. I thought of drilling the nut and wire locking but there's not much metal to drill into. Any ideas

Nigel

If you mean chainring lock nut, it's 25-30Nm and it's printed to the nut. And it's good to check the o-ring at the same time.

 

[irie]

If you mean chainring lock nut, it's 25-30Nm and it's printed to the nut. And it's good to check the o-ring at the same time.

See the below post - it is now 35 Nm

Edit: I used blue medium strength thread locker (Loctite 243) and put on tell tales so can immediately see if loosening. 6 months later still not moved.

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

Also put tell tales on cranks for exactly the same reason.

The left crank arm just fell off

When commuting to work this morning, I noticed that my left pedal was wobbling. I stopped to check, and suddenly had the complete crank arm in my hand :eek: I have a 15km commute to work (into the nearest town), most of it in rural areas. Luckily, I had reached the urban area, so I dropped in...

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[The EMF]

Correct me if I'm wrong, but 40 ft/lb is about 54 Nm! Isn't the cassette lock nut about 40Nm?

Just testing, and you’ve past……I’m of an age where I’m easily confused 40 Nm is the torque setting I tighten it up to

 

[Stihldog]

See the below post - it is now 35 Nm

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

I always thought that the torque could be increased slightly for this nut. I’ve removed it several times on different bikes especially when replacing a chainring or bearing seal kit.

My first attempt was a little difficult because my bike was suspended and moved around. Besides the left-hand thread, the castle nut removal tool would slip. There is a tool available which insures proper and secure attachment, but it’s expensive.

A rubber “O” ring was not installed with the original nut. But a brass “O” ring was along with a thin plastic “O” ring. When I installed an ethirteen chainring the chain alignment was incorrect. I had to remove the brass “o” ring and only use the thin plastic one. The ethirteen has an integrated spacer, or “o” ring.

I added a small amount of blue lock-tight to the castle nut threads and torque to the correct setting. That worked fine for the life of the chainring.

After removing the castle nut several times, this aluminum nut became slightly damaged. It’s very easy to accidentally cross-thread. The threads on the castle nut may have been stretched after repeated torquing. (After all, it’s only aluminum).

I’ve ordered two castle nuts. One as a spare and one as a replacement.

When I removed this chainring I discovered that the castle nut was loose. IMO the old castle nut is toast. No damage or noise occurred that would peak my attention. But this will become part of my regular preventative maintenance. I’ll watch this more often.

 

[RustyIron]

Has anyone found a way of locking the castelated chainring nut on bosch gen 4 drive units. Locktite last about six months. I thought of drilling the nut and wire locking but there's not much metal to drill into. Any ideas

High strength Loctite and 40 nm.

 

[DieBoy]

Has anyone found a way of locking the castelated chainring nut on bosch gen 4 drive units. Locktite last about six months. I thought of drilling the nut and wire locking but there's not much metal to drill into. Any ideas

Nigel

My lock ring has come loose twice - first time after ~4 months, then again almost exactly a year later.

It's a good example of why I hate bicycle mechanics. Something is loose that must be tightened, should be dead simple. Except you need a special socket for the lock ring (specific not just the manufacturer but also the model), and to get to it you have to remove the crank, which requires of course the specific crank-puller. Pah.

I haven't considered locktite yet, but I've learned to keep an eye on it and check every couple of months. Last time I tightened as much as I could.

 

[vman]

Has anyone found a way of locking the castelated chainring nut on bosch gen 4 drive units. Locktite last about six months. I thought of drilling the nut and wire locking but there's not much metal to drill into. Any ideas

Nigel

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

Okay so Europe and US Bosch disagree. Indeed. Or verbal statements differ from written statements as the latter could engage responsibility in case a strong torque would create damages. you could try to get a written statement of the US support, as I managed to get in EU ;)

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40 nm and since then no need for loctite or safety wire driling out of parts. I have two bikes that this has worked for after 1 year of having charin ring droppers - local bike shop that rents Trek Rails also uses this spec as they got tired of having to rescue people with dropped chainrings. For more back and forth you can read the above link, mostly its folks that will not change the torque on a nut that is printed 25 to 30 nm vs. me trying to get them to realize Bosch just screwed up when the printed the spec, but hey everyone is enttitled to their own approach on this issue.