Loose headset cups, are there different sizes?

[Kerplunk]

I've got a '90 Peugeot Athena 653 frame that I'm starting to renovate and have been trying out different builds. Last night I was seeing what it would look like with an ahead headset/stem. I've got an mart 1" headset but was able to push the cup into the headtube by hand without any real resistance. The campag threaded headset which was fitted before was the normal tight fit needing a press to get it in. Is there such a thing as different sized 1" ahead headsets, surely an inch is an inch?

 

[Old Ned]

There do seem to be slight differences. 'Manufacturing tolerances' I suppose it could be called. I had 3 Campag Record sets, one was tight, one perfect, one slack. But that was only with one frame I tried them in.

Have you tried yours in another frame? There might be a subtle difference in tube diameters ('Manufacturing tolerances'?).

 

[one-eyed_jim]

surely an inch is an inch?

Is the Mart headset JIS?

http://sheldonbrown.com/cribsheet-headsets.html

It seems that some Mart 1" headsets come in a JIS option, e.g.

http://www.wiggle.co.uk/mpart-comp-aheadset/

Normally the 27.0mm crown race will give the game away, but it's not unknown for JIS cups to end up in a box with an ISO crown race, or vice versa. Is there a mention of "JIS", "30.0/27.0" or similar on the packaging?

 

[Kerplunk]

surely an inch is an inch?

Is the Mart headset JIS?

http://sheldonbrown.com/cribsheet-headsets.html

It seems that some Mart 1" headsets come in a JIS option, e.g.

http://www.wiggle.co.uk/mpart-comp-aheadset/

Normally the 27.0mm crown race will give the game away, but it's not unknown for JIS cups to end up in a box with an ISO crown race, or vice versa. Is there a mention of "JIS", "30.0/27.0" or similar on the packaging?

Quite possibly, it did come with two crown races but I think that was something like 27 and 26.something or other. It is a mart comp so that would explain everything, will check the box later.

Why are these things so complicated.

 

[Kerplunk]

Crown races were 27 and 26.4. Couldn't see anything anywhere that said if it was JIS or ISO.

 

[one-eyed_jim]

If they've provided two crown races, it may be that they're also trying to get away with a compromise cup size. If your frame has been milled to the upper end of the size range for ISO cups, it may be just a little too big for a compromise to work.

If you have access to a good Vernier caliper or a suitable micrometer you can measure your frame and the headset parts you have. The pdf here has a table of head tube and cup dimensions for all the standards:

http://www.sutherlandsbicycle.com/Chapter12.pdf

You've got a few options. You can buy a headset that you know is ISO - a Campag or Stronglight would be a safe bet. You could contact the vendor of your Mart headset to see if they have any information on compatibility. In a pinch, Loctite makes products to seat loose bearings.

 

[David B]

Some other useful snippets here from the good folk of Park Tool;

http://www.parktool.com/blog/repair-hel ... et-service

David