• Managed to get hold of the bike, and although im going to need to confirm tomorrow morning im pretty sure ive got to the bottom of it, and as usual its pretty much what tester said.

    I put wheel in with the 42c tyre, and as @Saffronspokes had the displeasure of discovering it was indeed very much in contact with the frame. Next step was to check alignment of rear end on surface plate using BB face as datum, everything ok. I then put dummy wheel in with nominal 650bx42 tyre, and everything was ok there too. Next step was to put new stock wheel without tyre in, which was centred. Ive attached photos of the dummy wheel on surface plate for people as dull as me who find this stuff interesting.

    After waving a vernier at the wtb tyre, it appeared to be not only width wise oversized, but also very tall, even without taking knobbles into consideration. This causes us issues as after the tyre the stays need to bend in very aggressively to clear the road q factor cranks/road chain line, so if the tyre goes beyond where we expected it to be, it very quickly gets boxed in by chainstays darting inwards, away from the cranks.

    On their own these issues wouldn't be enough to cause any grief, but together they compound very quickly to what sam bumped up against this weekend.

    Nomimal clearance and real world clearance often dont have a lot in common, just compare the nominal 42c tyre guide in the picture attached versus Sam's photos and you'll see what i mean. He was sold a bike that said it cleared a 42c tyre, bought a 42c tyre and somehow found himself with a new permanent braking system instead of fashionable mixed terrain rubber attached to a boutique artisan frame.

    We have actually put a whole section on our (soon to go live)new website about this exact problem, and are looking at ways of mechanically squeezing a little more room if we can, but while narrow cranks, short stays and fat tyres are being used its always going to be a squeeze.

    Once im sure that this is the issue, im going to increase dimple size to match these tyres, and going forward im going to change dimpling process to move the dimple centre slightly further up to avoid this from happening in the future.

    Im also going to post some parts of a (unused) check list to show how many times we check rear end alignment throughout the build process. This isn't for any defensive reasons, but solely so that everyone who had clearance issues with the protoype frames knows we took that incredibly seriously and put a lot of checks in place to avoid it happening again.

    @Saffronspokes ive dropped a message on email, and will be sending proper report tomorrow, thanks again for spotting this. We sell a lot of frames abroad now so incredibly grateful this didnt happen in Malaysia! 😂

  • Thanks @coldharbour we got the email and really appreciate you looking at it so quickly and replying well out of 'work hours'. Really glad that hopefully you can sort it out for Kat.

    One thing it would really help to clarify is the '+ guards statement' on the website. The fact the frame is noted to have room for 42 plus guards is probably where quite a lot of our issues came from. It would imply that there should be ample space for a 42c tyre even if it comes up bigger as guard clearances are quite a bit. Anyway, in our case if it's fits 42 without guards that will be just fine. Thanks again for the swift action and hopefully it'll all be sorted this week!

  • Not a problem at all, we had a lot of practice dealing with clearance issues early on so this was just revision for us 😂.

    Ill post a pick tomorrow with a pdw guard in place so you can see where it would go, but of you imagine the there being an offset profile following the leading edge of the tyre guide in my post above, which would come right up to the stays in this set up.