I am a frame builder AMA

So I can ask ham fisted questions about geometry and you can design me a frame yeah?

I think that's how ama works ;)

Question for the frame builders regarding BB shell replacement. I have a Fothergill (more info at the link below) and due to wear and tear the BB shell has no thread left and have been told is to thin to re-thread and as such needs replaced.

Is this something that would be easy to do by a frame-builder or two much hassle / cost for the value of the frame?

http://www.classiclightweights.co.uk/builders/fothergill-james.html

Also, if it were to be fixed and re-sprayed is there a source for the old decals?

Thanks muchly.

For this sort of thing Winston and Mario Vaz are your friends.

https://www.varonha.co.uk/

a source for the old decals

The decals thread.

Thanks both, much appreciated.

I do some voluntary work for a local cycle charity. We’ve got some projects in mind that we’ll need some welding done on. We’re thinking about buying a TIG welder as that will help us with this work and also would be handy to have at the workshop for future bike stuff.
I was thinking that a fairly entry level TIG welder with a foot pedal is what we need.
Can anyone advise what’s a good starter option? Being a charity there’s not a huge amount of cash around but we want something that’s not complete rubbish.

Or the other option is going the gas brazing route which would be mor bike specific and then would it be possible to use it for some general, non-bike fabrication in steel plate?

Quick question...

I recently got some post mount disc 15mm thru axle forks from China and the brake mount is ridiculously close to the rotor (160mm) and the centrelock lock ring.

I have queried this with the place I bought it from but they have said I need to use a 140mm rotor not a 160mm and this will alleviate the problem.

Is this true or does it sound like they're fobbing me off with the incorrect rotor size argument...?

Picture below

140mm rotor would sit better, although it wouldn't change the position of the lock ring. I assume that is one of the BB lock rings and you have a 15mm axle? I would say there is a good chance 140mm would be fine.

Thanks - Yeah I have a 15mm axle.

The lockring is the hunt adapter one that came with the wheels - I can't fit the shimano lock ring that came with the rotors as the thru axle end cap blocks the tool. Do 140mm rotors fit on post mount brakes without adapters?

My other thought was to buy some of these - https://www.accu.co.uk/en/shim-washers/416329-HSHN-15-21-1-A2-BL and put between the inside of the fork leg and the hub on the tru axle to push things inboard a bit...

YEah you have to use that lockring. Fit a 140mm and see what happens, the calipers were designed to run 140mm or 160mm, just rotate mounting plate to adjust. I wouldn't put a washer on, the rotor has to be where it is to work with the caliper, plus you will knowck the dishing out, plus put stresses on the fork they weren't designed for (albeit minor).

Ok thanks for the advice

This is the hunt lock ring: https://www.huntbikewheels.com/products/shimano-sm-hb20-hmb618-centre-lock-ring-for-disc-rotors-to-fit-around-15-20mm-front-bolt-through-axles

The Shimano CL adaptor kit comes with a low profile steel lockring. That'll give you more clearance...

http://www.chainreactioncycles.com/mobile/ca/en/shimano-centre-lock-adaptor-sm-rtad05-/rp-prod130953

I've had to use it for the same reason. Annoyingly not available individually

It's lower profile than the Hunt one?

Any mm I can save around the fork leg is worth it

Yep, it's steel instead of alloy so much thinner. Still compatible with thru-axle hubs too (install/remove with an HT2 bb tool)

Perfect! Thanks for that link - I'll definitely be getting one!

You mention the mounting plate and rotating it to switch between 140mm and 160mm. I have the RS-785 post mount brakes

I'm afraid I can't tell what mounting plate you are referring to, pretty sure mine are just attached directly to the fork mounts

http://si.shimano.com/pdfs/dm/DM-BR0008-08-ENG.pdf

The flat mount versions have a reversible mounting plate by the looks of it.

Oh crap, sorry I thought you had flat mount. If it's the post mount then the mounts dictate position. If the manufacturer specs 140 then go with 140. I wouldn't stress about clearance at the lock ring too much, that is going to be the most rigid part of the fork, I don't think it's going to flex enough to rub.

Ah no worries, thanks for the clarification.

So in theory if the manufacturer says it is a 140mm fork then there should be no way I can get a 160mm rotor to fit.

The fact that I can mount a caliper with a 160mm rotor would thus dictate it is a 160mm fork and they're wrong / fobbing me off.

Thanks for the reassurance about lock ring clearance! For the sake of £8.99 I'll probably get the slimmer lockring but good to know it isn't an issue!

If it fits then it might work BUT they won't have tested it with a 160mm rotor.

Unless you are very large of volume 140mm front and rear with those calipers would be ok, although I always use 160mm on the front as theres no such thing as too much (modulated) braking power. In that respect 140mm seems a strange size for a road fork, but totally plausible that that is what they designed it to run.

Ah Ok

I think I assumed that as 160mm fits then 140mm wouldn't as the rotor would be too low and the pads would just pinch thin air. Sounds like i need to find one and test it...

Hang on. If the caliper fits without an adaptor with a 160mm then yes they are chatting rubbish it wont work with a 140mm. Pics of it on probs best.

It is definitely a 160mm fork! Issue lies with the combination of centerlock rotors and fork. I emailed Hunt and they said they have had the issue on a number of forks with their wheels. If forks are only ever tested on 6 bolt hubs then sometimes the centerlock to 6 bot adapters can rub on the fork leg (which mine did until I switched to centerlock rotors and no adapter). They recommend the narrower lockring that @Alb mentions above to give a little more room still.

But that wouldn't make the rotor rub against the boss mountings at the top edge of the rotor. That means either the boss is in the wrong place, the disc is sitting too far out, or the hub is holding it too far out.

Sadly still doesn't help with how close the top of the rotor is to the fork leg.