Chain ring bolt behind crank arm

[roubaixtuesday]

I've just bought, but not yet fitted, a large (46T) chainring for a triple.

The old one had a threaded fitting (sorry, don't know the technical term) for the bolt hole that hides behind the crack arm; the new one doesn't have such.

Before I get round to swapping them, does anyone know if I'll be able to swap over the fitting, or do I need a new one ( or even a different chainring with it built in)?

[531colin]

Just press it out; eg. Using a bench vide press the fitting into something like a socket ( spanner)

[roubaixtuesday]

Just press it out; eg. Using a bench vide press the fitting into something like a socket ( spanner)

Great, thanks, just checking.

[cyclop]

Just use 4 bolts instead of 5.Unless you,re a gorilla

[Sum]

If you got the Shimano chainring peg spanner (or similar), where the claw end is 90 degrees to the spanner arm, then you may get away with using an ordinary chainring bolt and nut if you wished. The peg spanner may fit behind the crank arm, as it does on my SRAM Rival which employs a hidden 5th bolt.

However it is a bit fiddly to do that so if you're replacing a worn chainring that's going to get thrown away, rather than swapping chainrings around for different purposes, then reusing the press-fit nut in the original chain ring will be the best option.

[Brucey]

NB.there is also a chain peg on most big rings. This can easily wind up in the wrong place, should a five-bolt ring be intended for the 'other' spider type.

Also you don't really need a peg spanner at all, if you have nice clean threads in your chainring bolts. I suggest using a metalworking tap of the correct size (which is usually cheaper anyway from e-bay) to clean up any female threads before greasing them.

[MartinC]

Took me a while to work out what the OP is saying and still not sure. I think they may be referring to the little peg that stops the chain dropping into the ring/arm gap. Are they saying that the new ring has a threaded hole for this but the peg is missing (or in the alternate hole for for other spider arrangement). A picture would help, moving the peg or using the one from the old ring are possible solutions.

[Brucey]

some 5-bolt chainrings are fitted with a captive female chainring bolt which can be pressed out as 531colin describes.

[slowster]

Took me a while to work out what the OP is saying and still not sure.

With cranks like the Spa XD2 chainset in the link below, which have one of the 5 bolts concealed by the crank arm, a special nut is fitted in the big chainring at that position. The nut is held in the chainring by serrations, because there is not sufficient space to use a peg spanner in the gap between crank arm and the chainring.

https://www.spacycles.co.uk/m8b0s109p31 ... chainrings

Set of chainring bolts with the captive nut:

https://www.spacycles.co.uk/m8b0s173p48 ... ble-set%29

[MartinC]

Ha! Everyday is a school day, I've been changing rings on XD2 cranks for years and never realised it was supposed to be a press fit - it's always come straight out with the lightest of finger pressure!

[cycleruk]

Is it like this:-

[roubaixtuesday]

Just use 4 bolts instead of 5.Unless you,re a gorilla

It's a tandem - definitely want all 5

[roubaixtuesday]

Is it like this:-
XD2.jpg

Yes:

[roubaixtuesday]

So, consensus is I can just press the old one out and refuse, I think?

[Brucey]

serrated chainring bolt sleeves are also found in some track/SS chainsets, where it is deemed advantageous to have the sleeve of the chainring bolt held captive. In any event, if you want to get the bolt tight, neither serrations nor peg spanner are required, provided the threads are not binding.