I’ve just got a C456 frame. I’m toying with the idea of slackening it, not least because the top seal cover and crown race are missing from the fitted Smoothie. On One are selling anglesets but only have the 90mm headtube version in stock, and I kind of assume won’t be getting any more in for the 105 head tube on my 18″ version. So, why are they head tube specific? What would happen if I tried to fit the 90mm version in a 105mm tube?

So, why are they head tube specific?

remember back at school, maths class, some smart arse pipes up

“what will i ever need Pythagoras for?”

well, now you have the answer.

the bearings won’t line up with the wrong set.

Yebbut…. on Work Components site the head tube lengths give “within tolerance” values of about 7 or 8 mm depending on the set. Eg the 44-49 2 degree version gives 100-108mm, then 109-116 etc etc. I’ve never seen one up close, so don’t have a mental picture of how they fit. I presume therefore that the 90mm version simply won’t align as you said?