Author Topic: Replacement Chainset ?  (Read 2758 times)

Replacement Chainset ?
« on: 08 July, 2008, 11:20:46 pm »
I've damaged the pedal thread on my right hand crank.  :-[  I took it to a LBS and the chap said it was beyond re-tapping but said he'd get me a quote for a helicoil insert.  I'm not expecting this to be cheap and from the look the bloke gave me neither does he.

Weird chainset. A Thun, the 46t chainring is fixed to the crank, no separate spider.  Possibly not worth fixing.

So if I need a replacement chainset what should I be looking for ? I take it the chainring should be 3/32" to match the sprocket ?

The bottom bracket is also an old style, Tange cup & cone (oozing grease), looks like it allows the chainline to be adjusted a bit. Not sure what size it is and I haven't got the tool to remove it.

Help!
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

border-rider

Re: Replacement Crankset ?
« Reply #1 on: 08 July, 2008, 11:25:39 pm »
It depends if you are keeping the chain.  If you are and that's 3/32 you'll need a 3/32 chainset.  Otherwise, if you decide to change the chain as well, a 1/8 chain would let you use a 1/8 chainset

But in general, a 3/32 chainset could be used with 3/32 or 1/8 chain.

Depending on what chainset you get, you may well need a new BB to get the right chainline.  Do you know what the chainline is at the back, or what hub you use ?

I've got an On-One budget chainset and that's pretty good.

Or these

http://www.byercycles.co.uk/05.htm

Re: Replacement Chainset ?
« Reply #2 on: 08 July, 2008, 11:42:46 pm »
The chain is a new looking  Sedis, I don't know what size. The hub has no markings,  I only picked the bike up last week as a first venture into fixed.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=140244575200&_trksid=p3907.m32&_trkparms=tab%3DWatching
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

border-rider

Re: Replacement Chainset ?
« Reply #3 on: 08 July, 2008, 11:46:23 pm »
If you have an old double chainset then you could play with that, with the ring on either the outer or inner position

Fitting a chainset to an existing fixed is often a matter of trial and error

Re: Replacement Chainset ?
« Reply #4 on: 09 July, 2008, 09:39:17 pm »
Well that was a surprise.  £12.50 for an insert, but they want the pedal so they can pre-fit it (glue it in!) and don't recommend removing it again.  I suspect this will be a medium term solution but at the moment that will do me fine until I want to start upgrading things.
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Zoidburg

Re: Replacement Chainset ?
« Reply #5 on: 10 July, 2008, 04:25:25 pm »
A thun is a well old piece of kit, a lot of LBS still have them floating around in the back of the shop gathering dust

You could pick up similar on Ebay for less than £12.50

Most definately not worth the helicoil repair

Re: Replacement Chainset ?
« Reply #6 on: 10 July, 2008, 04:41:31 pm »
Well that was a surprise.  £12.50 for an insert, but they want the pedal so they can pre-fit it (glue it in!) and don't recommend removing it again.  I suspect this will be a medium term solution but at the moment that will do me fine until I want to start upgrading things.

Strange.   I was sure a helicoil is a pretty permenant solution that requires no glue.  It's just a screw thread that is put into the crank.  i.e. tap out a bigger groove, scrwe in the helicoil thread, lo and behold you have a correct sized hole with a decent thread in it again.

I've got one in the back of the windcheetah where I pulled a thread out once.

Re: Replacement Chainset ?
« Reply #7 on: 10 July, 2008, 05:32:04 pm »
A thun is a well old piece of kit, a lot of LBS still have them floating around in the back of the shop gathering dust

You could pick up similar on Ebay for less than £12.50

Most definately not worth the helicoil repair

Only thing on Ebay was a Thun steel triple.   I don't want to get a replacement if I can avoid it , I'd rather ride it for a bit before I start changing things and have to worry about altering chainline etc.
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark

Re: Replacement Chainset ?
« Reply #8 on: 10 July, 2008, 05:42:24 pm »
Well that was a surprise.  £12.50 for an insert, but they want the pedal so they can pre-fit it (glue it in!) and don't recommend removing it again.  I suspect this will be a medium term solution but at the moment that will do me fine until I want to start upgrading things.

Strange.   I was sure a helicoil is a pretty permenant solution that requires no glue.  It's just a screw thread that is put into the crank.  i.e. tap out a bigger groove, scrwe in the helicoil thread, lo and behold you have a correct sized hole with a decent thread in it again.

I've got one in the back of the windcheetah where I pulled a thread out once.

The comment about gluing the pedal was my feeble attempt at a joke.   The guy at the LBS said he's removed pedals from helicoils before with no problem
Not fast & rarely furious

tweeting occasional in(s)anities as andrewxclark