ZS44 Headset

[saab9002]

Good afternoon all,
Hopefully someone can explain this problem I've got, I bought a frame from a German supplier in July but have since had two major ops,
so progress to build has just started. The headset I bought is 44mm top and bottom bearing cup size, as is the frame, but when I came to
fit them I found after not getting anywhere, that checking the frame it measures 43.70mm, the headset measures 44.00mm.
I have contacted the supplier of the frame and in no uncertain words he stated that the frame is the right size and to check S.H.I.S, so I have and for ZS44 it states that the frame bore sizes should be 44.00-43.95mm.
Needless to say we seem to have come to an impasse except through paypal the supplier will refund my money if I return the frame at my own cost,(to Germany). The frame is want I wanted and to buy a "correct" headset will cost less than returning the frame.
So could one of you far more experienced builders of bikes please tell me what are the correct sizes and if I need to buy a specific type of headset.

kind regards Chris

[slowster]

You might need to get the head tube reamed. From https://www.parktool.com/blog/repair-help/head-tube-reaming-and-facing:

Many headset cups are held in place by a “press fit”. The headset cup has a slightly larger diameter than the head tube inside diameter. Generally, differences of 0.1-0.25mm are considered adequate for a press fit. If the pressed cup is more than 0.3mm larger than the frame inside diameter, it may be very difficult to install, and frame damage may result.

[Brucey]

..I have contacted the supplier of the frame and in no uncertain words he stated that the frame is the right size and to check S.H.I.S, so I have and for ZS44 it states that the frame bore sizes should be 44.00-43.95mm....

the SHIS chart I just looked at said the frame should be 43.90 to 43.95mm ID for ZS44. The cup should be 44.1mm dia when it fits this this frame dia, i.e. there should be 0.15 to 0.2mm interference.

Even if your measurements are correct (and with cheap calipers they could easily be 0.2mm out) then you are still within sandpapering range. If not then a quick ream will sort it out.

If you want to check your calipers (to about 0.02mm accuracy) then this is simply done using the inside/outside diameters on a standard (smallish, stiff) cartridge bearing as a gauging piece. This will enable you to tell if your measured discrepancy between ID and OD is entirely 'real' or not.

This kind of problem is not uncommon when building bikes and there is more than one way to address it.

cheers

[Bowedw]

I had something similar in fitting Hope cups to a Giant frame. I spun the headset cups in a wood turning lathe with some fine wet and dry abrasive held against it in a gloved hand as heat builds up quickly.

[saab9002]

Thank you all for the fast replies, bowedw, Brucie and slowster,
I am over the moon to be proved correct in my assumptions and actually do not feel any animosity towards the supplier of the frame, also I'm a qualified engineer, just about to retire, Nov 30th but will put the cups in soft jaws and take out 0.20mm then all will be well.
I might even forward this conversation to the German bike frame supplier and forgive him at the same time

Thanks again
regards Chris