braze on front mech too high

[english john]

I want to change my front chainset from a 53/39 to a 48/34 (stronglight)

Problem: My new(old) bike hase a braze on for the front mech , which looks far too high for the 48/34, even after adjustment down as far as it will go.
It will be too high compared to the general guidance of 1mm above the teeth of the outer ring, but will it work anyway ?

It works fine with the 53/39
1.Will a braze on adaptor below the real braze on work - possibly, looks a bit tight
2.Change to a triple , with a 53 outer

Has anyone else solved this problem ?

[CJ]

Get rid of the "braze-on" (hacksaw and careful filing will do the job) and fit the clamp-on variety.

[gaz]

.

[Valbrona]

Using a cylindrical needle file, you could try extending the length of the slot in the bracket downwards. Or you could remove it with a hacksaw and file, and use a bracket.

[english john]

My front levers are oldish Campag, so I think it works on friction ? So I will have a play

I do have a dumb question though...

If I do hacksaw the braze-on off , then where can I get some cheap touch-up paint (and what type to use) ?

Please keep improving my DIY skills everyone - Im starting from a very low base !!

Thanks

[CJ]

Model shops sell tiny pots of enamel paint (used to be Humbrol - perhaps it's Chinese now) in many colours, so you'll probably find something near enough. Give the bare metal a coat of primer first.

[York Commuter]

If there isn't a modelling paint that is a good match is there a nail varnish?

A coat of nail varnish with a coat of clear varnish on top will be pretty good until time for a re-enamel.

[PW]

Humbrol is still on the market. A coat of Finnegan's red oxide then the enamel (if it won't match use black, the mech and the muck it throws off will cover a tiny mark where the braze on was). If it matches then add a coat of clear enamel varnish. I think it's called Gloss Cote but don't confuse it with the special plastic glue which comes in the same type of bottle. Read the very small print first!

[Valbrona]

...It will be too high compared to the general guidance of 1mm above the teeth of the outer ring, but will it work anyway ?

Here's mine.

It's a 38T outer. Rather than setting the front end of the mech to clear the ring by 1-2mm it has to be set so the tail end clears the chainstay by 1-2mm.

Mine shifts fine on friction; indexed front shifting may be less forgiving.

At the budget end of things, Shimano do an FC-M151 7 speed/triple front mech designed for use with a small (42t) outer chainring. The idea being that the cage is a little bit shorter so as to not foul the chainstay. Cable routing for this part is optional - under the BB old style, or along the top tube new style.

[Steve Kish]

I went from a 53 outer to a 48 outer on a braze-on and although the cage looked high, worked 100% perfectly.

[Raph]

I've had this problem a couple of times - on one I removed the braze-on as mentioned above, on the other I filed the slot downwards, also as mentioned above.

Both solutions worked perfectly, though the touch-up paint job was a bit rubbish - a mate now owns the bike so I have to see the ugly job I did every time he gets it out - BUT, at least I know it was functionally decently done as it hasn't rusted and I did it about 20 years ago.