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TL;DR

I thought I could figure out repairs myself but clearly I'm a moron.

I replaced the chain and chainring on my fixie last Saturday, and this morning it got scary loose on me. I started to feel what felt like slack in the chain, but when I pulled over to check it out I noticed that all five of the bolts on the chainring were halfway to falling out.

From start to finish, here's everything that I did when removing the worn ring and putting the new one on:

  1. Remove old chain (do not remove crankset from bottom bracket)
  2. Starting with an Allen wrench and a screw driver, I started removing the nuts/bolts holding the old chainring in place. Successfully remove three of the five. Glare at rust on threads of nut.
  3. Fight with the remaining two bolts, which seem to have seized. Add a small amount of WD-40 to seized bolts. Fight some more. Swear. Attempt to use a hammer to tap on screwdriver to loosen bolts. Lament my lack of a third arm. Swear some more.
  4. Take a break. Look accusingly at old chainring. Pretend to do something else, in order to lull it in to a false sense of security.
  5. Attack bolts without warning.
  6. Realize that the only thing I'm doing is stripping the nuts and coming seriously close to accidentally stabbing myself with a screwdriver.
  7. Admit defeat, go to LBS. Get a proper chainring nut wrench and a replacement set of chainring nuts/screws.
  8. Cackling with the newly found power of using the proper tool, removing the frozen bolts and the old chainring.
  9. Small amount of WD-40 on a rag used to clean rust transfer off of crankset, then wiped down with clean rag
  10. New chainring in place, finger-tighten new bolts
  11. In star pattern, use Allen wrench and chainring wrench to tighten bolts
  12. Repeat above for good measure
  13. One last time, just crank those suckers as tight as possible
  14. Install new chain
  15. Ride to/from work, no problems.
  16. Ride to work, almost die, s#!t bricks.

All told, I rode about 20 miles between installing the new chainring and the extreme loosening that I had this morning. Did I miss some fundamental step in this process, or was this just bad luck? What can I do to keep this from happening in the future?

EDIT: Now with photos!

I only removed one of the bolts because I didn't have the time to take the whole thing apart. If necessary, I can disassemble the entire thing when I have time.

Also, man my bike is dirty. :-/

Outside of chainring Front

Inside of chainring Back

Outside after I removed a bolt Outside without bolt

Inside after I removed a bolt Inside without bolt

The bolt I removed My nuts - side view! My nuts - top view

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I would have gone with new nuts and screws. And grease aluminum threads. –  Blam Jun 11 at 23:27
    
I did get new nuts and screws. Step 7. –  mikeTheLiar Jun 11 at 23:38
    
You mention rust. Are both the spider and the new chain ring steel? And are the new bolts steel? –  andy256 Jun 11 at 23:40
    
Then do the new screws and nuts go the same distance. I have seen nuts that don't let the screw go trough and the spine on a single can be more narrow. Are you torquing on nut or chain ring? Did you miss a spacer. And 7. says nuts (no screws). –  Blam Jun 11 at 23:44
1  
And take a picture before you take it apart. –  Blam Jun 12 at 1:50

3 Answers 3

Consider that you should use either grease on the threads of your chainring bolts when installing chainring bolts, you want to be able to easily remove these later as chainrings do need to be replaced over time. Get some grease on the faces of the chainring and crank spider where they touch the chainring bolts. Some people are fine with blue loc-tite, but I prefer not to have to force it.

Don't just tighten them once and assume it's ok. Go around the ring and tighten every other bolt until you've tightened them all. You can do a star pattern if you prefer, just don't tighten them simply in order around the ring. Make a couple passes and incrementally increase tightness. You want to ensure they are tightened evenly, so that none of them are loose while others are over-tightened. Use a torque wrench if you're really worried about over-tighening.

Make sure you're using the appropriate length of chainring bolts (which doesn't seem like a problem from the photos). Some bolts (actually the sleeve/nut) are made longer to go through the crank spider and 2 rings (or bash guard), while others are made shorter to go through the crank spider and a single ring.

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A drop of blue Locktite (use sparingly on each bolt) will fix this problem: http://www.loctiteproducts.com/p/t_lkr_blue/overview/Loctite-Threadlocker-Blue-242.htm

It says threadLOCKER but it mainly provides thread friction so bolts don't back out of their own accord. RED locktite on the other hand, locks it on there.

As to why those bolts backed off, some of the steel bolts I've seen have a very low friction coating on them and with the high torque you get with the fixies, well, they can back off.

Use locktite :)

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1  
Just a note - the loctite colours aren't universal, I think the colours are US consumer specific, but certainly when you look at their engineering products it's not that simple. The idea of a light threadlocker is a good one though, and to make it lighter still you can screw/unscrew the thread a couple of times as it sets - you still fill the thread with a higher friction material. –  Chris H Jun 16 at 8:27
    
Interesting, didn't know that. Blue is Loctite 242 in the US, hopefully they don't switch the numbers around. –  dunc Jun 28 at 19:52

Given the instructions from Surly are grease and not loctite I don't agree that loctite is the answer. Same with instructions from sram. Something is wrong for those to go loose in a day.

SurlyInstructions
Are you sure you have 6mm (single)?

That bolt looks long relative to the nut to me. I seems like more thread on thread is a good thing.
SingleChainrignNutBolt

TruVativ
Understand you don't have a TruVativ but only place I found torque. For steel torque is 12-14 nM. And they show the nut on the chainring side (like you have it).

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