Front mech problem: too high over chainring

nickvonfiction

I bought a frame a few weeks ago and have started building it up. I’ve got one issue I’ve not encountered before which is that the front mech can’t be set low enough on the braze on to be within the proper height above the big ring - it’s about 7-8mm above. My outer ring is 50t, which is obviously a variable affecting the clearance over the mech, but even with a 53t, it still seems too high, based on pix of the previous owner’s build. I’d be grateful for any suggestions for resolving this one. I thought initially maybe a band-on mech below the braze on would work but that would put the mech too low, unless you removed the braze on completely, and I’m not sure that’s a good idea on a Ti frame even if I wanted to do that. Another way could be to get a much bigger outer ring – this may have been a custom frame built for a monster - but this would then affect the rest of the gearing and probably not be the set-up I want, so I am reluctant to go down that route. Is there any kind of adapter to fit to the braze on that could drop the mech 5mm, or some other solution, other than giving up and selling the frame?

Pix:
With a 50t


With a 53t

on-yer-bike

Looks like the braze on bracket has been put in the wrong place. They should accommodate compact and standard chainsets, no problem.

nickvonfiction

Hmm, I thought that could be an option but who would make such a schoolboy error!? Possibly this lot.

peteone

Never seen that one before. A braze on adapter below the fixed mount may work but may be a bit trial and error.

http://www.sjscycles.co.uk/images/produ ... G28410.jpg

Matthewfalle

If you don't want to sell the frame or get the braze on cut off and rewelded, you could dremel the slot for the mech longer - so long as you have enough meat on there to keep it clamped in then dremel away.

If you aren't confident then any frame builder would do this for you but its not actually a big job.

Is it second hand or new? If new, send it back and get a refund. Alternatively, have a word with the seller and say its not fit for purpose and you want your money back.

nickvonfiction

Thanks for the suggestions.
What sort of adapter would one use?
Re dremelling, unfortunately the ideal position is right at the bottom of the braze on, so I think that might be a bit dodgy.
It's a second hand frame, but it was quite a bargainous Ti frame, so I would quite like to get it to work!

peteone

You can buy braze on adapters which is just a band on with fitment for a braze on mech. Maybe this would sit below the current fitment and allow you to lower your mech. It's not gonna look great but should solve the issue.

http://www.sjscycles.co.uk/images/produ ... G28410.jpg

mrdsgs

http://www.velotechservices.co.uk/shop/ ... 7386000002
just the bracket with two holes, plus the hex bolt and you just need a nut behind the braze on and plate leaving the other hole in the plate just below current slot.

keef66

It's clear it's been welded on too high. Looks like nice round tubing so I think I'd be grinding off the braze-on and fitting a band-on adapter. Do it carefully / progressively so you don't get the area too hot.

nickvonfiction

Thanks very much for your thoughts and suggestions - much appreciated.
I was thinking of filing down the slot, but the ideal position would mean taking the spot between the bottom of the slot and the bottom of the braze on thus compromising the braze on totally, so I would probably be best off getting the whole thing removed and stick a band on instead.
It is about 14cm from the bottom of the braze on slot to the bb centre so it doesn't seem abnormal positioning.
I am going to see if I can get a cheapo 53t off ebay and see if that makes for an acceptable arrangement - but then I guess there may be a problem with switching to a 34t inner. Gah.

flasher

Grind the mount off and fit a band-on FD, should be very easy especially as it's a ti frame, no repainting involved!

Monty Dog

Titanium's a pretty hard metal to work with hand tools - it blunts them pretty quickly - but grinding-off an using a band-on would be my preferred option if wanting to stick to a 50x34. If looking to switch to a 53 chainring, you'll need to fit a 37 inner otherwise the chain may rub on the bottom of the cage - 52/36 might be a better compromise.