Chainset compatibility question

My late 80's 531c Raleigh Gran Tour is back on the road after being hung up for 15 years. It's a fab bike, I've now been reminded!

I was thinking of just keeping it going while I saved for a modern bike, but I've realised that it's a viable proposition to keep it long term and invest in it (albeit to a small budget).

It has a 42/52 Gipiemme chainset. I live in hilly country and want lower ratios. The ideal would be to fit a compact chainset and keep the old-model 105 front derailleur.

Can I do so without changing the bottom bracket? I'm guessing it's a standard square taper but I haven't measured the length of the BB axle or anything else, if this is necessary to answer the question.

Is such a modern chainset compatible? I know that some come advertised as "square taper compatible" but I'm guessing there may be more to it than this?

Have any of you guys done this? Apologies for talking about a non-purist old bike!

Thanks in advance.

The most important thing is that the bike gets ridden.

You'll in all probability need to change the bottom bracket, as they tend to be shorter these days.

I would look for a square taper Campognolo chainset - it will look roughly right and there are usually plenty of NOS ones kicking about on eBay.

Thanks for your advice. So when you say they're shorter these days I'm assuming you mean that the length of each square taper protruding from each side of the bb (or just the chainset side?) is shorter?

If I get an old Campy bb will it automatically be compatible or are there a selection of sizes available, only one of which is compatible with a modern compact crankset?

How can I tell that the current bb is incompatible, if indeed it is? Is it that the length of the square tapers will be too long?

Is the threaded dimension (ie diameter) of the bb pretty standard despite the age of the bike? Or should I measure the internal diameter with calipers?

Do I need to take into consideration the width of the bottom bracket housing in the frame itself, or again is this a standard width old vs modern?

So many questions for just one task, all help is greatly appreciated!

The length is that of the BB shaft, as it's symmetrical each side.

There are two types ISO and JIS, which are subtly different. Shimano and Japanese stuff is JIS, Campag is ISO. Campag BBs are hilariously cheap and last forever.
There are also Italian threaded BBs and English threaded, plus there is a whole load of weird old French stuff in oddball sizes from planet Citroen. Later French bikes have so-called English threads.

Hopefully your one will be simply an English threaded BB and you can buy the Campag chainset and BB and be riding happily into the sunset...

Try this:
http://cgi.ebay.co.uk/Campagnolo-Centau ... 4aac4c4147

You are a true gentleman, thanks for taking the time and for your great advice!

My frame is a Raleigh 531 so if that doesn't have an English thread I don't know what will!

Thanks a million,
Ross.

Bottom brackets of that era were commonly around 115mm in length, whereas stated most recent chainsets use something shorter, around 107. Simple advise is to find the chainset you want and get the right bottom bracket - they're not too expensive and inherently lower maintenance than the older open bearing types.

hamster":3gwrb41r said:

The length is that of the BB shaft, as it's symmetrical each side.

Click to expand...

nope, theyre not. ok, maybe the more modern cartridge type is, I dunno, but Ive several campag and dura-ace cup and cone BB's and theyre definitely not symetrical. Indeed, when Ive had similar probs to the OP, Ive switched the axle round to get a better chainline.

OK, fair enough, not exactly symmetrical to the last mm, but they are within 3mm or so. They don't just take up the extra length all on the right.

Compact chainsets don't necessarily need to be "new school" though - something like a Stronglight 80 or 100 (both with an 86mm spider) will provide rings of suitable sizes and may well fit the same length spindle as your Gipiemme cranks.

David

Hi.

Or keep the Gipiemme chainset and change the freewheel and rear mech(for a long arm one).

Ride with that setup and then decide where to go spec wise.

Simple?

Roadking.