Slipping Chainring on offroad fixed setup
 

Has anyone ever encountered problems with their chainring moving/shifting while putting backwards pressure on the cranks ?
The chainring bolts are tight, yet the chainring holes are just slightly larger than the bolts themselves. I am getting some pretty significant wear and grinding of the ring where it is obviously slipping back and forth in the hole of the crank spider.

...........and yes, before I get the peanut galley response THE BOLTS HAVE BEEN TIGHTENED USING A 5MM AND CHAINRING NUT TOOL.
So the bolts are as snug as any SS setup I have run in the past.

I noticed similar slippage while on road, running a set of Profile carbon cranks with the removable spider.
I had to loc-tite the spider retaining ring to alleviate this on the road.

Setup:
(FSA V-Drive Extreme cranks 104 bcd, with a Snap 38t BMX 6061-T6 ring).

Never had this happen. How about a close up picture of the setup?

The chainring nut is wider than the bolt. Is this still smaller than the ring or is the bolt not extending through to the ring hole? Have you tried another set of nuts? They are cheap enough that you might want to do that. Also, are the chainring bolts/nuts single speed specific? If not, I've seen the nuts bottom out and the setup will seem like it's tight but actually has a little play in it.

Running fixed off-road you really shouldn't be putting enough back pressure on the setup that it slips easily unless something else is going on. Without seeing in person I'm guessing the bolts are a likely problem.

Sounds like you've found the problem. Try bolts that fit?

photos...........

Attachment 54278

Attachment 54279

the hole in the chainring is larger than the nuts; see photo,
I have not tried a different set of nuts. I thought that these were steel, but they might be alloy, which could also be an issue.
These are standard nuts, but I have them holding (2) rings, as this is a double chainring setup, with a flip-flop hub..see photo

also, I have about 3/4" play in the chain as any tighter causes bearing noise.
I realize the chainline is off a bit, due to the setup
my chain tension seems to have loosened up a bit, I think the chainrings have shifted.

the bolts are the same size as the other 5 pair of nuts that I have.
the chainring hole is slightly larger however.

do your SS rings fit exactly the size of the chainring hole?

Problem: you need longer nuts/bolts to hold 2 rings. SS bolts are meant for a single chainring.

The nuts should fit flush inside the chainring bolt holes so that when the nut is tightened all the way, everything is flush. There should be no play whatsoever.

This was the only link I could find:

http://cgi.ebay.ca/New-Chainring-Bol...QQcmdZViewItem

but I think that's what you need, in the right diameter.

well that setup is never going to work right again. you have already worn out the chainring holes large enough that not amount of torque on the chainring bolts will keep that ring in place IMO. you will probably have to get a new chainring

Are the chainring nuts made for a double or single ring? If they are made for a single you need to get the ones made for a double. If not, the chainring is the issue, but I've never seen a modern (4 arm) with hole larger than a standard set up. My bet: a new set of double stack chainring nuts and bolts will fix your problem.

i had a problem similar to this one with my fixed gear, except i was in the uncomfortable position of my chain actually slipping all the way off whenever forceful backwards pressure was applied to the cranks. I thought of everything that i could as to why this was happening and it came down to a very simple solution. My chain alignment was severely off. Something i didn't notice until it was brought to my attention (i'm kinda blind) but maybe its something you should check. it was relatively simple to fix after i noticed the problem.

The gear is slipping. He's not dropping the chain. Read the post.

I currently have a set of DOUBLE (ie: built to hold 2 rings to a spider setup on the crank) chainring bolts on the setup.
A single would never have reached through both rings and the crank spider.
Good idea on the problem, but not the case for my setup.

I went home last night and started to size out all of my chainrings.
I found that my 'Snap' (the one pictured) my Blackspire (x3), and a Bontrager ring (44t from a std mtb setup) ALL had slop and movement with a chainring bolt in the hole. So I am saying that the tolerances seem to be very large.
**note, I used the lower, or the back side piece to size, as it is the larger of the two chainring components.............(the receiver, or the girl part if you will).

I have a Sugino 42t that came on my Profile carbon crank spider that has very little, if any movement of the chainring bolt inside the hole.

My question would be, how much 'slop' do others see in the tolerance of the chainring bolt and the chainring hole?

In the meantime, I will either put on my BMX cranks, or I will hamfist a single ring, and flip the bolts around backward on two of the four holes.

Love SS riding, but the amount of equipment BS I have had to deal with since starting has been SIGNIFICANT.

But are the nuts made for a double? Judging from your earlier photos I'm guessing they might not be. See picture for example.
http://www.wiggle.co.uk/images/e13%2...0kit%20ind.jpg



Very little. Your photo shows a lot of obvious play in your ring/bolt combo.



Well, you are doing messing around with something that is not a straight up single chainring/cog combo.

Worst case, swallow your pride and head over to the local bike shop and get an expert opinion.

+1. In fact, the fit is usually snug enough that I have to pop the backs out of the ring individually when I remove all the bolts.

It definitely sounds like you have the right bolts and the wrong nuts. Get the right ones.

your ring could just be worn out I have old rings from bmx where the bolts were a little loose and the holes are deformed

The nuts need to go though the crank arm and into the chainring just below flush. The nut prevents the ring from slipping not the bolt.

I am currently using the 9mm CR bolts on this setup.
I have used the 6 and 9 mm versions of CR bolts, and never had an issue on the geared bikes(ie: normal MTB triple) setup or single ring/SS bikes.

OK, so I am correct in assuming that people are recommending the 15mm CR bolts.

http://www.lickbike.com/productpage....9;0247-03'

I don't think these will work, as they will be too long.

I understand the consensus solution here; and what the problem appears to be.
bolThe 'nut end' of the bolt does not extend far enough through the inside CR, the crank spider, and then out through the outside CR.

Let me also caveat that I had NO issue with this setup on the road.
Which leads to another point; which is that offroad riding seems to put different stress on the drivetrain and bike setup.

So as I see it, I have four solutions.
1. Run a single ring setup on the inside of the crank spider with a single CR bolt.
2. Run a single ring on the outside position of the crank spider with single CR bolts inserted backward (or a double CR bolt through the crank spider and CR, facing normal position).
3. Purchase some 15mm CR bolts, and grind them down to 'just fit' the length of both rings (ie: one ring on the inside, and one on the outside of the crank spider).
4. Bag the entire crankset, put on my CroMo cranks and go with a BMX chainwheel.
any other suggestions??

I also appreciate the fact that I am trying an unconventional setup having a flip flop with two front Chain Rings.
I also know that the comment about swallowing my pride and going to the LBS was meant in a helpful way.
I don't mean to open a can of worms here, but..........
I must state that my LBS has expertise, and does have SS/FG riders that work there.
That being said, they are not usually even remotely capable of solving my problems better than I can myself.
The reason I frequent forums like this is to learn for myself, how to do these things.
I understand they have to pay overhead and what not, but I would not be able to ride bikes if I had to rely on paying for 'service'.

Something about give a man a fish and he eats for a day, teach him how........................

I am struck by how much wrenching knowledge I have developed since I started to ride SS/FG.
Mostly because I discover the inherent manufacturing incompatabilities that exist in the industry, and it forces you to McGuyver a lot of things that you see as possible on the bike setup.

Anyway, thanks for the suggestions.
I will get back on what I decide on and how it worked out.

OK update.

I put on a set of 9mm (double) CR bolts with a single ring on the inside of the crank spider.
I then put 242 (blue) loctite on the bolts and nuts, and then cranked them down with a 5mm hex and a CR nut tool.

approx 20 miles into a ride, I get the dreaded loose CR bolt creak.
all bolts had come loose, at least partially.

I think i will put on my BMX crankset and see how that works out.

so my question is, how do people keep their setups tight and bombproof?
what a PITA

I know you don't want to do it, but take it to a shop. Setting things up and getting them right isn't hard, there must be something you are overlooking. Swallow your pride and spend a couple of bucks to get the knowledge that appears to be elusive. Trying to be helpful here, not bust your balls, but you need someone to look at it, words on the web aren't going to solve your problem, we've done all we can.

are your bolt holes on the chainrings ovalized?

no, but they are slightly larger than the spider holes.

all of my SS rings are like this, lest the 110bcd 42t sugino ring I have.

I appreciate your being helpful.

how many fixed gear riders does your LBS have exactly?

To answer your question, several. But it doesn't matter, you don't have a fixed gear issue, you have a chainring/bolt/crank issue, the fixed gear portion is irrelevant. Any decent mechanic will be able to help you.

I currently have have 3 off-road fixed bikes setup. I've never had any of these problems and I do all of my own wrenching. I appreciate that you want to learn how to do this yourself, but sometimes that means you need a teacher. You need another set of eyes: whether it's a mechanic at the LBS, a friend or a local rider with more experience.

Did you grease the threads first? Properly greased bolts hold ****ing tight. In any case, take it to a shop already.