Headset sizing help

Marko1962

I'm in the process of ordering a headset for a Ribble TT frame I'm building up but don't know what size headset I need, 36 x 45 or 45 x 45, I have no idea what to measure to determine a 36 or a 45.

Any help will be greatly appreciated.

Weejie54

The "IS" system is considered the most common. The name Integrated System is not a registered trade name. The system uses the 45-degree bearing contact in the frame. The bearings for the 1-1/8 inch steering columns use a 41mm outside diameter with a 45-degree bearing contact in the frame. The bearing may be marked "36-45". The first number refers to the inside bearing contact with the headset race or centering cone. The second number refers to the frame contact.

http://www.parktool.com/repair/readhowto.asp?id=68

Marko1962

I did read that at Parkers but it made no sense. Re-reading it again makes it a little clearer.

Monty Dog

The only definitive answer is to speak to Ribble - there are numerous models of integrated headset with only small differences that you only find won't work when you try assembling the frame. IME the majority are the 'Campagnolo' pattern 45x45, but Ribble might be different

Marko1962

Received an email from Ribble

You require a 45 x 45 ITS headset for our TT frames.

Quoted in case someone else has the same query.

PeterBL

Monty Dog wrote:

IME the majority are the 'Campagnolo' pattern 45x45, but Ribble might be different

Does "Campagnolo" designate the diameter? Or is that the same for all integrated headsets?

In other words, are all 45x45 integrated headsets compatible, or are there other variations?

Monty Dog

For the definitive answer, download the headset technical guide from the FSA website - it has drawings and dimensions of all the different models - there are lots! The Campagnolo pattern refers to both the diameter - ID 41.8mm of the bearings and 45 degree chamfers. Park Tool has a guide too.