[Christopher Robin]

My old frame has a CC headset that's ZS44 upper and EC49 bottom. So tapered steerer.

My new frame needs a 1-1/8 upper bearing and a 1.5" lower bearing. So IS 41/28.6 and IS 52/40. This is for a Santa Cruz frame.

I know the bearings will fit fine...but is possible to convert an external headset into an IS headset by just not using the headset cups???

 

[Harold]

My old frame has a CC headset that's ZS44 upper and EC49 bottom. So tapered steerer.

My new frame needs a 1-1/8 upper bearing and a 1.5" lower bearing. So IS 41/28.6 and IS 52/40. This is for a Santa Cruz frame.

I know the bearings will fit fine...but is possible to convert an external headset into an IS headset by just not using the headset cups???

Uhhh, no. You can't just "not use" the headset cups if your frame requires headset cups.

There are structural differences in the frame between IS and pressed cup types. IS headsets use the frame to support the bearings, whereas pressed cup types use the pressed cups to support the bearings. If you did what you wanted, there'd be nothing to support the bearings and no way to properly preload them.

https://www.parktool.com/blog/repair-help/headset-standards

 

[Lone Rager]

^^^ that's how I first read it, but after re-reading it, I believe he is asking if he can use the parts from an external headset, except the cups, on an integrated headset frame. It sounds plausible, but IDK for a fact.

 

[Aglo]

OP, check the bearings numbers, if they match you can use them.

 

[Harold]

^^^ that's how I first read it, but after re-reading it, I believe he is asking if he can use the parts from an external headset, except the cups, on an integrated headset frame. It sounds plausible, but IDK for a fact.

Ah, if that's the case, then yeah.

OP, check the bearings numbers, if they match you can use them.

Yep

 

[Christopher Robin]

Haha yeah I didn't quite word that clearly...

Looks like the bottom bearing fits fine in the new frame, and the crown race looks like it seals it up as if the bearing was sitting in an actual headset cup. The top bearing sticks out a bit above the headtube in the new frame so top cap doesn't seal it up. So I'll have to look into that...I'll probably just go to the shop down the street and let them figure it out.

 

[Lone Rager]

Yeah. Headsets can get pretty complicated. There are 5 dimensions for a headset bearing that need to match the application: ID, OD, thickness, inner chamfer angle and outer chamfer angle (36 or 45 degrees). And those things are different for the top and bottom bearings. (There are actually two more, the depth of the chamfers, but I've never seen these specified.)

Chamfer angle is important and not easy to check. A bearing with the wrong angle can still seem to fit and work properly but it can cause problems further on. Nowadays, headtube contact angles are all 45 degrees as 36 has fallen by the wayside.

 

[eshew]

When you find replacement bearings do yourself a favor and pop off the seals and top off both sides with water proof grease. After reinstalling the seals make sure you coat those liberally with waterproof grease as well.

Those bearings don't really seal that well, one wet ride and they will get water intrusion if they aren't topped off and have the extra grease to reduce intrusion.