Chainring change

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PAB855
Posts: 221
Joined: 26 Apr 2014, 3:07pm

Chainring change

Postby PAB855 » 7 Jun 2018, 6:44pm

I have a 1982 road bike but am no longer able to use the big ring and don't have low enough gearing for modest hills using the inner ring and bottom gear
Is it possible to change from a 52, 42 to something like a 42, 32 or 34.

I realise the 5 point fixings PCD is 150mm(?) and that's about the same as the tooth PCD of the 34t ring, but I have been told each of the five arms can have a short distance piece attached to accommodate the PCDof the 34t ring by lying radially inwards towards the centre of rotation to reach the 34t fixings.

Have I been told 'porkies'? I find it difficult to see how it can be done because of the shape of the shoulder used for the location and support of the chainrings as the five arms of the crank have a piece extending inwards below the location shoulder .

Any glimmer of hope for a solution?

Cheers

rmurphy195
Posts: 1349
Joined: 20 May 2011, 11:23am
Location: South Birmingham

Re: Chainring change

Postby rmurphy195 » 7 Jun 2018, 8:24pm

Your bike probably has a square-taper bottom bracket (the cranks mount onto a square spindle!).

If you can't get replacement rings of the correct PCD, maybe have a look at Spa Cycles website for a complete crankset? I deduce from your post that its a twin chainring setup, so this might be a good starting point https://www.spacycles.co.uk/m2b0s109p31 ... chainrings

Having said that, if you explore thier website you'll find chainsets and chainrings, and maybe if you email them the details of your current chainset (make, current no.of rings etc) they might be able to make a recommendation.

And of course you could also look into replacing the rear sprockets with bigger ones!
Brompton, Condor Heritage, creaky joints and grey hair
""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !

rjb
Posts: 3236
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Chainring change

Postby rjb » 7 Jun 2018, 8:56pm

I think you are looking for a double to triple chainring adaptor which uses an inner double to mount a 3rd ring like this one.
Image
They were made by the likes of stronglight and ta. I dont know how available they are now. Probably like hens teeth and cheaper to just replace the chainset.

What are using at present? What is the pcd. Can your front mech cope with a small inner ring?
At the last count:- Focus Variado, Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D

PAB855
Posts: 221
Joined: 26 Apr 2014, 3:07pm

Re: Chainring change

Postby PAB855 » 7 Jun 2018, 9:31pm

Thanks both of you

Firstly, Spa give plenty of choice. I think a 48/34 would do fine.

The upper jockey wheel is already close to the sprockets so changing the rear end doesn't look possible.

The photo of the adaptor looks as if it's what was described to me.

I'm further forward anyway.

Cheers

PAB855
Posts: 221
Joined: 26 Apr 2014, 3:07pm

Re: Chainring change

Postby PAB855 » 9 Jun 2018, 2:07pm

Order placed with Spa Cycles for a 48, 34.

Many thanks to all

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Mick F
Spambuster
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Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Chainring change

Postby Mick F » 9 Jun 2018, 2:39pm

rjb wrote:I think you are looking for a double to triple chainring adaptor which uses an inner double to mount a 3rd ring like this one.
Image
They were made by the likes of stronglight and ta. I dont know how available they are now. Probably like hens teeth and cheaper to just replace the chainset.


Stronglight Z'lite Impact like I have on Moulton.

http://www.stronglight.com/stronglight/ ... uit?id=276
The middle ring fits on the "double" spider and has holes in it to fit the inner.
Mick F. Cornwall

Keezx
Posts: 417
Joined: 20 Dec 2014, 10:44am
Location: The Netherlands

Re: Chainring change

Postby Keezx » 9 Jun 2018, 7:27pm

The special chainrings are also called "triplelizer" and can still be found at small shops and Ebay.
Couple of years ago I bought one for my Campagnolo Chorus carbon double chainset (square taper) with 39 T and 74 BCD holes and it works perfectly despite the missing shifting aids.
74 BCD offers the possibility for a 24 or 26 T grannyring

rmurphy195
Posts: 1349
Joined: 20 May 2011, 11:23am
Location: South Birmingham

Re: Chainring change

Postby rmurphy195 » 9 Jun 2018, 9:39pm

PAB855 wrote:Order placed with Spa Cycles for a 48, 34.

Many thanks to all


Let us know how you get on. PS You might have to shorten your chain, of course!
Brompton, Condor Heritage, creaky joints and grey hair
""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !

PAB855
Posts: 221
Joined: 26 Apr 2014, 3:07pm

Re: Chainring change

Postby PAB855 » 17 Jun 2018, 8:55pm

Yes, all changed over after removing four links. The rear mech is at about its limit, but it all works fine in my garage.
Tomorrow is test day. Fingers crossed.

Cheers

PAB855
Posts: 221
Joined: 26 Apr 2014, 3:07pm

Re: Chainring change

Postby PAB855 » 4 Aug 2018, 8:58pm

Belated update.

The bike went like a dream at the recent Velo Retro based in Ulverston over the weekend of 13 to 15 July. We did the 30mile ride and only had to walk up the last 100yards of the last hill which was ok for us.

The whole event was fantastic, one of the most enjoyable events I have ever taken part in.

I love this old bike, it's one of the best I've ever had and it had been hidden away for 30 years in a garage, so I count myself as extremely lucky to be its current owner.

Thanks for your tips.

Cheers

gxaustin
Posts: 465
Joined: 23 Sep 2015, 12:07pm

Re: Chainring change

Postby gxaustin » 5 Aug 2018, 10:27pm

I fitted a Stronglight crankset with 46/34 rings on my 1978 Falcon. So much easier than the 52/42 or even 39.