What is the width of the chainstays at the rear flat mount points? I may have to give this frame a try too.
Is this where you mean? I can take a more accurate measurement tomorrow if this is not sufficient.
Lovely frame.
Can you say more about how the Carbonda headset for the integrated bar is inferior to FSA's? I'm buying FAS's stem and have no objection to buying their headset. I could wait till after the frame with headset arrives to decide about ordering the FSA headset, but I'm very curious.
In order to have the expander flush with the top of the handlebar, you would need to have an offset of about 3mm due to the thickness of the part that sits on top of the fork and stops the expander from dropping straight in. In the image below, the top half is the FSA ACR expander, and the bottom half is the one Carbonda ships with the bike, which you can find on aliexpress. Both headsets were tightened to a semi-snug fit (expanded, but still able to rotate freely) so show where they would approximately sit within the steerer tube.
The FSA ACR expander covers a good region of where the stem bolts are. The Carbonda one barely covers half of the top bolt. Note that the expander cannot sit any higher. Although you can have the stem sit slightly lower, the length of the knurled region that pushes against the steerer tube is just about enough to cover the space between the two bolts and would need some fiddling to get right.
Also the knurling on the FSA ACR expander definitely feels like it has much more grip. When tightening both to a semi snug fit, I had a harder time extracting the FSA ACR expander.
The bearings I got from FSA also ran smoother. As for spacers, FSA spacers were out of stock, but I know they can be put together without removing any cables as they join at the space where the cables route (like a padlock), whereas the Carbonda ones join together at the gap for the steerer tube, with the gap for cables fixed.
I am aware that carbon tubes are strong when there are equal directional forces and that the Carbonda/AliExpress headset is sufficient for 99% use case, but I believe that the additional expense for a FSA headset is justified by having peace of mind.
Also, you cannot use the routing on the FSA ACR expander that was intended for the front brakes as it seems that Carbonda has routed the front brake hose to have a single entry single exit channel (from the flat mounts to a couple of inches above the crown race). If I try to push a routing cable from the top of the steerer tube, I couldn't get it to exit at the fork disc brake exit hole, though this could be ineptitude on my part. This doesn't bother me much as I'm okay with using the designed method of all four cables going down the same headset gap, but may be an annoyance to some.
In any case, Carbonda are pretty happy to accommodate to small customisations, and if someone were to want to definitely use the FSA ACR style routing, you could probably request for no channeling on the front brake hose.
