Never fitted an integrated headset before, its a Cane Creek 40 One of these going into a Dolan Preffisio frame.

I’ve removed the old headset, the new one doesn’t appear to be anywhere near size, I expected the bearings to drop into the frame and maybe require a little tap, the Cane Creek bearings are about 1mm all around, I don’t fancy whacking that into the frame to make it fit!

Bearings are positioned with the angle down going into the frame correct?

I’ve probably missed some change in standards somewhere but I thought you were pretty safe with 1.1/8 integrated?

Dolan recommends this but as Merlin had the Cane Creek on for £20 I went with that as I thought it’d be slightly better quality.

both are 36/45 which I thought was the important part…

Usually the external angle is 45 for integrated IS headsets, the internal angle only matters if you want to reuse the crown race and compression ring (or the crown race is integrated in the fork).

Try to measure the frame ID and see what type of headset you have: http://www.parktool.com/blog/repair-help/headset-standards#article-section-11

Dolan recommends ITS the Cane Creek is IS – I’m guessing these are two very slightly different standards, both about 1mm apart and I should have bought the one from Dolan…

both are 36/45 which I thought was the important part…

Unfortunately for us headsets aren’t that easy to choose and several “standards” exist
If you look about halfway down the Wiggle page that you linked to there is a SHIS code (IS41/28.6 IS41/30) which is explained here

Thanks, I’ve checked the diameters, the cup width in the frame is 41mm, the bearings are 42. The headset came in a clear polybag from Merlin with no ref to IS41 or 42 on the bag, Cane Creek 40’s come in both standards.

I’ll call them and send it back and see if they’ll swap it.

Thanks all!