1965 Moulton Speed Resto

[Stephen Lounton]

hello everyone just found this forum and looking for advice , I have a 65 moulton speed i am restoring , i have replaced the bottom bracket for a cartridge square taper type , i am wanting to replace everything for new modern components , i have been looking for single speed chainsets but the makers reccomend certain axle lengths however the bottom bracket i have used is per the original 120mm , am i right in asuming i should stay with the original length, also the original chainring was 52 teeth ( 4 speed sturmey archer hub 16 " wheels) could i use 46 or 48 tooth chainrings ? any advice would be greatfully received ,, kind regards steve

 

[RecordAceFromNew]

I know next to nothing about 1965 Moultons, but believe it is NOT straightforward to put a modern BB on it.

Regarding your questions, usually one picks the chainset, then based on the chainset spec and chainline requirement identify the BB to go with the frame. The reason being a chainset for square tapers will deliver a certain chainline with a certain BB spindle length, and it is usually desirable, whether with or without front derailleur, to get the chainline right.

Firstly do you know or can you work out, in your case, what the chainline you want is?

Secondly for square tapered there are primarily two modern standards, JIS and ISO. Do you know which your new BB is?

We might be able to work out which chainsets might work for you with the two answers above, but it could be tricky, which is why normally one starts from picking the chainset, not BB.

Hope it helps a bit.

 

[Stephen Lounton]

not sure how to work the chain line out to be honest, but i think the new bb is jis ,as the squar taper is quite thick and dont taper down as much as i,m lead to believe the iso ones do and its made in taiwan ? i did replace a bb on an old moulton about 10 years ago but i cant remember the parts i used , and dont have the bike now as my ex wife binned them , thank you for the reply ,

 

[Stephen Lounton]

well i could easily choose a chainset then get another bb , i just thought if the original was 120mm i should just replace the same size , i thought thats how you did the chain line , excuse my ignorance , i just really want my moulton to be on the road as i want to do a vintage ride this summer thanks again

 

[Stephen Lounton]

i just looked on sheldon browns web sit and in a chart it says 40.5 to 42 mm for older hub geared bikes not sure if this is a standard ?

 

[betty swollocks]

You should be able to get all the specific advice you want here.

 

[Stephen Lounton]

Thank you I will look

 

[Stephen Lounton]

evening , i just measured the chainline and it is 42mm i measured from the centre of the seat tube acros to where the chain ring would be and lined up from the rear sprocket , hope this is right , so where should i go from there ,

 

[RecordAceFromNew]

evening , i just measured the chainline and it is 42mm i measured from the centre of the seat tube acros to where the chain ring would be and lined up from the rear sprocket , hope this is right , so where should i go from there ,

The good news, is that 42mm is pretty much the standard for single speed. What that means is practically all single ring chainsets will deliver that or very close to that chainline with readily available BBs for standard 68mm shell, English thread bottom brackets, which are pretty much standard for modern or even 30 year old road bikes (with the exception of those made by spaghetti eaters ). These guys e.g. and a myriad of others will be able to provide single ring chainsets, from funky to classical, and the BBs that deliver 42mm chainline on such frames.

However, I suspect an important but possibly outstanding question here, as I indicated at the beginning, is given the age of your bike what is the best way to put a modern BB on the frame. In the OP you said you "have replaced the BB for a cartridge square tapered type", has the modern cartridge BB been installed securely and do the threads match that on the BB shell? What is the width of the BB shell? Do you know if the BB shell has Raleigh's old proprietary threading and if it has have you taken a look at this?