1/8" chainring on Campag Record road cranks

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pq
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1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 9:44am

The cranks on my fixed are creaking like [rude word removed] and have resisted all attempts to solve the problem. I've been riding the cranks (Record Pista) since 1982 (and the Royce bb for more than 20 years) so I can't really complain.

I now have a redundant pair of 2000 Record road cranks which don't creak, so an obvious solution is to retire my existing cranks/bb and use those instead, but I'll need to get a chainring. The cranks use the crank arm itself as one of the anchor points for the chainrings, which means I need a chainring to suit - one of the holes is countersunk on the other side and the width needs to be right or the ring won't run true. This would be easily done if I just bought a compatible road chainring, but I'd rather use 1/8". Has anyone done this and knows of a chainring which will do the job? Needs to be 44T by the way.

Thanks.
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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 9:46am

Blimey, I didn't think that was rude enough to get censored...
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Mick F
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Re: 1/8" chainring on Campag Record road cranks

Postby Mick F » 7 Dec 2017, 9:51am

Auto editing. :lol:

Why are your cranks creaking?
Is it that the square tapers are worn?

I think I've read on here somewhere that you can cure this. Maybe someone can come up with the method.

Failing that, I think you'd be better off with new Pista cranks as I don't think you can get one-eighth rings for a Record chainset.
Mick F. Cornwall

pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 9:56am

I don't know. I've tried all the common solutions and none have worked, so probably dodgy tapers. For the last few years I've just poured a bucket of water over it before riding which sorts it for a few hours.

I have very little time for bike tinkering these days, so I'm not going to spend any more time messing about with them, especially as the cranks are way beyond the end of their normal lifespan - 35 years of regular use is ridiculous. With the more recent cranks 15 mins will see everything swapped over and running silently, so that's what I plan to do.
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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 9:58am

Forgot to mention that you can get 1/8 aftermarket chainrings which, according to the manufacturers, do fit, but they don't mention the specific issue with the Record crank, so I'm slightly sceptical. All that sort of stuff is made for the urban hipster crowd - there's loads of it about.
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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 10:01am

Here, amongst other places: http://velosolo.co.uk/shopcrank.html
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Brucey
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Re: 1/8" chainring on Campag Record road cranks

Postby Brucey » 7 Dec 2017, 10:09am

you can run 1/8" chain on 3/32" rings. That would be an easy solution. I am sure you can make an ordinary 135mm BCD 1/8" chainring fit the newer record cranks in the outer position, but it will probably entail some machining (not easy). I don't think that anyone makes one that will fit without any issues.

It would be easier to fit a chainring in the inner position BTW; you would just need a spacer of some kind. But I wouldn't use that chainset at all, not without a lot of careful thought; the chainline won't be correct to replace a pista crankset unless you get a different BB. The 1982 pista BB will of course be the wrong length (and may be the wrong taper too).

BTW if your old cranks are creaking then that can surely be stopped, unless it is a crack that is gradually making its way through the crank itself....

If the creaking is 'cured' by a bucket of water, it sounds like dodgy chainring bolts. It is not sufficient to make sure they are tight; take the chainring off, clean out any black gunk from the interfaces, grease the bolt threads (only) well, and reassemble, making sure the bolts are tight.

cheers
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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 11:05am

The current set-up doesn't use a pista bb, just the cranks. The Royce bb I'm using is longer than a pista which gives a perfect chainline. Cliff at Royce confirmed it was suitable for the cranks.

If I swap the cranks, I'll be using the matching 102mm Record BB which by my reckoning will give a perfect chainline with the ring in the outer position. If it's slightly out, spacers will sort it. On the Royce, the chainline would be miles out.

I did the chainring bolt thing a while a go, but I'll try it again. The bike is my winter hack and it's always covered in gunk.

The other issue is that the existing 144mm BCD ring is extremely worn, so I'll need to buy a chainring anyway, so if I'm going to swap cranks, now is the time to do it.

Oh and I know a 3/32 will work - I've had a 3/32 ring on it since the mid 90s. I'd just sooner use a 1/8 if I can.
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Brucey
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Re: 1/8" chainring on Campag Record road cranks

Postby Brucey » 7 Dec 2017, 11:35am

unless the chain has been kept (too) tight the valleys in the chainring and the reverse side of each tooth on the extant chainring may not be worn. This means that the chainring can be turned and remounted (sometimes needing longer bolts and ideally with tiny spacers in the counterbores).

BTW I meant 'the wrong taper' for you to mount the newer record cranks on the extant BB: IIRC the pista cranks have stuck with an older (pre ISO) version of the square taper.

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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 12:47pm

The existing chainring is way beyond that and has already been turned. The teeth look more like sharks teeth, and are now incredibly thin. It always amazed me that the transmission was so smooth with the chainring in such a state. Different story with the sprocket of course, worn ones never ran smoothly - I'm currently using a beautiful EAI which is the best sprocket I've ever had. In fact that's why I don't want to use the 39T chainring already on the replacement cranks - it would make my very expensive 18T EAI redundant.

I didn't know Pista cranks have a different taper - I just asked Cliff if the bb I had would work - he said it would, and for a long time, it did.
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Brucey
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Re: 1/8" chainring on Campag Record road cranks

Postby Brucey » 7 Dec 2017, 3:03pm

it occurs to me that if the chainring has already been turned, but tiny spacers have not been fitted into the ring counterbores, this may have contributed to the squeaking; I am not sure the required pressure can be sustained by the chainring bolts if they are not working on something that is pretty solid.

Check the cranks for cracks, for sure, but It might be that a new 144 BCD chainring will solve your problems. Velosolo will probably have something suitable. A 44T chainring is what you need to go with your favoured EAI sprocket? I wonder if someone has one kicking around in their shed?

cheers
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robc02
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Re: 1/8" chainring on Campag Record road cranks

Postby robc02 » 7 Dec 2017, 5:38pm

pq wrote:Here, amongst other places: http://velosolo.co.uk/shopcrank.html


I use a Velosolo 1/8 chainring on mid '90s Chorus cranks (135mm pcd) on one of hubgeared bikes and it works well. The quality of the 'ring is good - it was a bit more round than the 3/32 rings I previously used, and seems to be lasting well.

pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 5:51pm

That's an interesting thought about the chainring. I have a whole box full of 144 rings, and while none of them are the right size, I have some which are close enough for a little test.

Thanks for the stuff about your Chorus cranks, but my problem is specifically related to Record cranks which have a different way of attaching the chainring.
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pq
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Re: 1/8" chainring on Campag Record road cranks

Postby pq » 7 Dec 2017, 5:54pm

Forgot to say, yes that's why I need a 44. It gives me the 66" I want with my EAI sprocket.
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Des49
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Re: 1/8" chainring on Campag Record road cranks

Postby Des49 » 7 Dec 2017, 10:39pm

Regarding the creaking - do you use the titanium axle bolts with the Royce bottom bracket?

We have a Cannondale M1000 bike, fitted with a Royce BB, also over 20 yrs old. The chainset is a fairly recent Shimano and a very slight creak would appear after a ride or two no matter what I did. This never happened with the previous Suntour chainset.

I swapped the titanium allen key fitting crank bolts and reverted to some normal steel hex head bolts, this seems to have worked.

Now I am not sure if this is down to the material, or even due to the fact that I am able to tighten the steel bolts down harder.