chain rings

[lotus 30]

I have a williams Ab77 chain set and would like to get some larger ring gear for it say around 60 tooth which bolt holes do you measure to get the correct ring gear. a car wheel is diagonal but that prob will not work. Picture of a 62 tooth i have made an adapter for an old williams cotter pin chainset to a more modern ring gear

[Tigerbiten]

Look up "Bolt Circle Diameter" for the correct distances.
Sheldon Brown's BCD crib sheet -> https://www.sheldonbrown.com/cribsheet-bcd.html

Luck .....

[thirdcrank]

It's the same size as TA 5 pin as in Cyclotouriste equipment and also the adaptor (in your lowest pic.) as used with Stronglight 49D. Even standard sizes are now in rocking horse doodah territory. AFAIK, larger sizes like sixty teeth were only ever made to special order.

[lotus 30]

Thank you people something to work with now. Merry christmas andy

[thirdcrank]

As a bit of a blast from the past, here's a compilation of some old TA ads.

http://www.classiclightweights.co.uk/co ... -comp.html

Of course, chain wheels wear out. Perhaps your main hope is that as devotees of older kit get older, they switch to lower gears: there may be more big rings surviving than smaller ones.
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PS I see Hilary Stone has a 5pin Cyclotouriste outer with 57 teeth for £45. (Scroll down on this page.)

http://hilarystone.com/chainringstacyclotourist.html

[Mick F]

I have a 61t on my Moulton bought from Spa.
https://www.spacycles.co.uk/m2b0s113p17 ... -outer-61t

[lotus 30]

Thanks for that link to SPA and thank you for the link to Hillary stone

[fastpedaller]

What's the project? A small -wheeled bike, or an E-Bike ...... Or do you just have VERY strong legs?

[gaz]

Commercial adapter to 110 or 130BCD. I cannot confirm compatibility with a Williams Ab77 and I have no knowledge of availablility of suitable chainrings in either modern BCD.

[lotus 30]

What's the project? A small -wheeled bike, or an E-Bike ...... Or do you just have VERY strong legs?

Ha ha Its a Moulton special i have got a five speed sturmey archer hub i have built it into a new rim my first wheel build un assisted. i have machined some cogs and got two of them on the hub. and i have made an adapter for twin chainring on an old williams cotter-pin crank set. I have tested and it works fitted two sturmey archer bar end 3 speed levers. to operate the 5 speed. i shall fit twin levers on the down tube for the front changer and rear mech. I have got a period Benelux super sixty rear mech. so i will have a 20 speed touring moulton. Got to find a front changer yet i will prob go for another Benelux. Or a cheep campag.

[lotus 30]

Commercial adapter to 110 or 130BCD. I cannot confirm compatibility with a Williams Ab77 and I have no knowledge of availablility of suitable chainrings in either modern BCD.

That looks interesting chain set but i am ok for them i have kept mine from the 1960's when i was a school boy time trialist.

[andrew_s]

There are a couple of people making modern versions of the 49D/Cyclotourist chainset (e.g. Velo Orange, SunXCD), so new, off the shelf, chainrings and bolts aren't very difficult to find.

The main difference between the new versions and the originals is that there's a bigger gap between outer chainring and crank arm, so that the crank arm doesn't prevent modern, wider, front mechs from moving far enough to shift onto the big chainring.
This could also be a problem with your Williams chainset.

Long term , provided that it fits, using standard 110 or 130 bcd chainrings with a 5-arm SunXCD spider is likely to be cheaper than using 6-bolt 49D pattern chainrings.

[lotus 30]

I have managed to get a 64 tooth chainring for the TA adapter which fits my williams AB77 cranks. i am missing bolts to fix the chain ring to the adaptor has anyone got a picture of the original type they used as normal allen key type are to big in diameter.