Removing a stuck chainring bolt

[Brucey]

this photo shows a bit more about what they are like



you get about half the threads in engagement vs normal bolts (four full threads in the ones above, so will wear/strip easily with re-use) and there is a nasty crevice in the bore of the assembled bolt (not present in a normal bolt) that easily fills up with water. The bolts shown are not really suitable for every triple chainset, because both ends are slightly domed and are likely to interfere with the chain when it is running on the inner ring.

The ones shown above are from bikediscount.de but there are a few different types available. They all have the same issues AFAICT.

cheers

[reohn2]

Thanks Brucey,I was completely unaware of them,goes to show you learn something new every day

[Mick F]

Thanks for that Mick,where did you get them from?

They are on the Stronglight ZLight triple chainset as from new.
http://www.stronglight.com/stronglight/ ... uit?id=276

[Mick F]

PS
If the fancy takes me later, I'll have a look at my Chorus Triple on Mercian and see if they would fit to check out Brucey's point.
Mercian is 53/42/28

Not sure about half the threads though. He may be right. They seem very solid to me and very secure.
As I say, I'll check it all out if I can.

Still tinkering with stuff, as I'm still not well enough for riding these infernal machineries!

[Brucey]

note also that the socket which accepts the 6mm key is usually very short. This will probably limit the torque on a new bolt, even if the short engagement doesn't. Needless to say if you carry a typical multitool, you are no better off by the roadside; you need separate 5mm and 6mm keys (in some cases two 5mm keys IIRC) to tighten the bolts.

IME because you can easily assemble these bolts without any grease on them, that is very often the way that they are assembled. Since they corrode more easily too, this means they are quite often found badly seized on bikes. Obviously (because of the crevice) they are still more prone to corrosion even if they are greased, and well-greased bolts of the standard type give very little trouble, so.....

cheers

[Mick F]

Got the chainset off Mercian.
Chorus Triple.

The internal fitting on Campag is the same length as the internal fitting on the Stronglight.
Slotted on Campag, 6mm Allen on Stronglight.

The external fitting on Campag has 6mm of thread, and the external fitting on Stronglight has 5mm of thread.
Both take a 5mm Allen key.

I tried the Stronglight combo on Chorus and there isn't the slightest issue.
Using the longer external Chorus and the internal Allen Stronglight, they don't screw up tight.

Photos.

First is the Chorus Triple inside side.
Note the odd bolt that goes into the crank arm.

Second are the four halves of the bolts.
Campag top and Stronglight bottom.

Third is differences between the Campag on the left, and the Stronglight on the right.

Fourth and last is the Stronglight fitted into the Chorus.

As you can see, it fits well, and if I had some more of them, I'd use them instead of the Campag.

[Brucey]

the worry with a triple is that the head of the bolts -if they are longer, which yours (like most such bolts) clearly are- will chatter on the chain when running small-small gear combinations, and/or interfere with upshifts onto the middle ring. I'm sure that won't be a problem in every case but in some it will be.

cheers

[Mick F]

Yes, possibly.
It wouldn't be the case with mine though. Plenty room for small/small.

[Sweep]

https://www.youtube.com/watch?v=E6SCwijgdyQ

Thanks again for this slowster but doesn't work for my sitation because of the angles - only the big ring is in place on mine and its teeth are too far away.

[Sweep]

Have you tried gripping the rim of the slotted nut with a pair of pliers?

Nothing to grip on i'm afraid rheon.

[Sweep]

re sweep's stuck bolt;
it can't be that stuck, after all how could it have been tightened that much?

I would suggest holding an allen key in a vice, sitting the bolt onto it, .and then using a drift and a very small hammer to 'massage' the sleeve with radial blows, from different directions. It will soon slacken off.

In this position you can use heat to your advantage too.



cheers

Will try, thanks.
On your separate point on grease, i did note that this brand new chainset had no grease at all on the bolts and sleeves. I always thought this was good practice when screwing metal to metal.
I must admit I didn't use any grease myself but this was because it was a trial assembly only. I would have greased the bolts if the chainset was going into service on a bike.

[Sweep]

Update - sorted it.

I did try your drifting idea brucey but I think I had just jammed the thing too hard for it to work - and I was starting to damage the slot, which would compromise future efforts.

So I locked one of these in a vice:

https://uniortools.com/eng/product/1781 ... nch#794175

(handy for vice clamping due to the square blockish nature of the mount)

sat the spider with stuck bolt atop it and started dremelling.

Managed to get a slot cut in the outer (the bolt) which, just, enabled the peg spanner to gain some purchase so that I could turn the bolt out of it.

Now for my other thread related to this/what I was hoping to do before I screwed things up.
It's here:

viewtopic.php?f=5&t=133379&p=1407510#p1407510

[MikeF]

Thanks for that Mick,where did you get them from?

They are on the Stronglight ZLight triple chainset as from new.
http://www.stronglight.com/stronglight/ ... uit?id=276

They are on my Stronglight "New Impact" chainset (that I've had for 5 years), and I have an unopened new set.

[fastpedaller]

On your separate point on grease, i did note that this brand new chainset had no grease at all on the bolts and sleeves. I always thought this was good practice when screwing metal to metal.

I noted the same lack of grease on the threads of my Spa triple chainset when I bought it 5 years ago - the bolts holding the granny ring on were particularly tight and 'screemed' when I undid them - as I'm sure I would have done if the tools had slipped and my hand had contacted the chainrings!
With threads then greased everything seemed a lot happier

[Mick F]

I've always greased stuff on assembly if required.
Copper grease is best, but any grease is better than dry.
Chainring bolts included.



Sweep ............ great that you're sorted now!