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#1
10-20-2024, 02:15 AM
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Campagnolo chainring bolt fell off JRA and questions
So... have been having too many JRA issues lately.
First, cruising along and started feeling a rhythmic bump sensation. I look down and "sigh" a bulge in the Vittoria tire sidewall. Good thing I wasn't bombing downhill. Second, going up a steep hill a week later and the chain kept coming off the small chainring even though I was not shifting and already on the largest cog in the back. I thought it was something with the FR setup and fiddled with that later. Seemed OK on a short test ride around the bloc but then on a real ride, the chainring just came loose! Questions: 1) Do people check their chainrings on a regular basis? I have to note I have never checked my chainring bolts for the past 13 years on my FSA crankset on my previous bike. 2) I have Campy Chorus 12 speed mechanical setup. It is very confusing what is the right replacement bolt set. Anyone know for sure what to get? I tried to run by one store this weekend and they didn't have anything for it in stock and there are various options online. The 1st one should be it yes? FC-CH1200 https://www.ebay.com/itm/37452855330...8AAOSwUb1nB2JJ https://www.condorcycles.com/en-us/p...42220462735510 https://wickwerks.com/products/campa...ring-bolt-set// 
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#2
10-20-2024, 06:01 AM
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I can't answer Question #2, but in regard to Question #1, I never check my chainring bolts but I have experienced them coming loose, maybe once. It could have been a maintenance fault on my part or I just never checked them on initial installation.
The cure would be a mere drop of Loctite 242 on the male and female threads.
__________________
http://hubbardpark.blogspot.com/
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#3
10-20-2024, 06:56 AM
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Quote:
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#4
10-20-2024, 07:21 AM
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Quote:
__________________
Chisholm's Custom Wheels Qui Si Parla Campagnolo
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#6
10-20-2024, 10:38 AM
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Chorus-12 seems to be particularly susceptible to this. A number of us have had CR bolts come loose on that crankset.
Yes, blue loctite on CR bolts always now.
__________________
http://less-than-epic.blogspot.com/
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#7
10-20-2024, 12:09 PM
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Many years ago I lost two chain ring bolts and others had loosened when I inspected the crank due to bad shifting.
Lesson learned. Don’t answer call for dinner before tightening all bolts when when working on bike. Second lesson learned. Campy chain ring bolts are expensive.
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#8
10-20-2024, 12:14 PM
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His shoes FLEW OFF!
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#10
10-20-2024, 04:47 PM
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I run Campag Chorus 12 and found some loose chainring bolts while cleaning. I took them all out and loctited them, then marked the heads and onto the crank/chainrings with a permanent Sharpie. Now all I have to do is glance at the witness marks and make sure they line up.
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#11
10-21-2024, 07:34 AM
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Might be different for different riders but I’ve had trouble with rings. Having a bolt fall out is really weird though. Usually if a bolt comes even marginally loose it should start driving you nuts with noise way before it falls out.
I’ve had issues with both SRAM and Shimano chainrings loosening. Only certain ones though. Others were bombproof. Usually once they’re taken apart, cleaned, and the bolts are replaced and torqued properly they go back to being long term reliable.
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#12
10-23-2024, 05:08 PM
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Quote:
Since 2021, the recommendation has been that after removal, say for chainring changes etc, a new bolt set is used & that in the case of Chorus, the bolts are loctited with a small amount of Loctite 248. In the case of RE and SR, new bolts, fitted dry. In both CH and RE / SR, chainring bolt toque is 8nm. In RE / SR locking is provided by the galling of the (relatively) soft bolt anodisation against the hard chainring anodisation. Chorus chainrings are differently treated, little or no galling occurs, so the bolts do need a little loctite. With a new crankset, it's worth checking the code on the back of the crank (small white or sometimes black decal) or the box ... and making sure it ties up with the chainring sizes you have. Rings often get swapped around at the distro or in-store to make the crank length / ring combo needed and not all mechanics are careful about re-tightening bolts or using loctite, much less, know (or dare I say it, bother) to use new bolts. The last three digits of the alphanumeric code give you the clue to the crnak length and chainring combo - so for instance, FC20-CH12028 translates as Front Chainwheel, 2020 model year (i.e. year of launch, not manufacturing year), Chorus, 12s, 170mm (because 170 is the only available crank length ending "0") 32 / 48 because they end 2 & 8 respectively. So, if you have bought a 170x32/48 crankset and the unit is marked CH12062, that would suggest it was originally 36/52 and it might be a good plan to check the chainring bolts. Normally, a loose bolt will cause a creak, long before it drops ... Last edited by gfk_velo; 10-23-2024 at 05:14 PM.
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#13
10-24-2024, 12:02 AM
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install question
Ok--this is probably recall bias but maybe I do recall hearing some slight creaking before the catastrophic loosening. Alas I didn't consider this as a cause for the sound--was wondering if it was the bottom bracket.
Another question--about the install. I couldn't find a good manual or youtube on this and not sure the order of putting in the parts. The manual picture makes it look like the washer sits up against the inside of the crank, yes? Just tighten screw from the front into the bolt pushed in from the back? I'll probably just have the shop do it since I also don't have a T30 head (just 25 on the Silca torque wrench).  ++++++++ Originally Posted by AngryScientist View Post https://support.campagnolo.com/media...rt_A_Rev02.pdf Well, I can tell you for certain that my 12sp 4-arm uses T30 chainring bolts, threaded in from the back, but accessed from the front (so you turn them counterclockwise to tighten). And for sure, if you try and use a T25 on them, you'll strip them out.
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