Front Mech Range Question

Hello again. I really am being a pain with all these questions I know but, here we go again.

I have a rather nice 600 chainset. It was supplied with a 53 tooth big ring and very nice it is too. I bought a new small ring and with Ed's Gospel ride a possibility, I made it a 38 tooth version.

This means that even I may need to spend some time in the big ring! The one on my other bike is more or less NOS as I prefer a higher cadence and don't have the legs I used to have.

So, I'm thinking of getting another less big big ring as it were. My question is this. The frame has a braze on bracket for the front mech which is a standard 105 jobbie. Will the slot that allows a little up/down adjustment for the mech have enough to allow for the smaller ring?

Does anyone here run a 38/50 combo on an older frame with the braze on bracket?

Thanks as ever.

I'm glad you like the crank and big ring

You should have no problem with the front mech if you decide to use a 50t ring, but the easiest way to tell would be to fit the crank with the 53t to your bike, fit the front mech in the correct position, and then see how far down in the slot it will go.

The difference in radius between a 53t and 50t ring is about 6mm (107.5mm vs 101.5mm approx), but bear in mind that the front mech outer plate should be between 1 and 3mm vertically from the tips of the large chainring when the chain is in the small ring, so this might give you some extra adjustment room.

Depending how much material there is around the slot in the hanger, and how good/orignal/special the frame is, you could file the slot a bit longer to fit the mech lower.

If all else fails, I do remember seeing some adaptors that fit between the hanger and mech to fit it lower down (can't remember where I've seen them though).

hope this helps!

Not a great picture but I had a 48t ring fitted on this with a braze on mech, it worked fine although was further from the ring than I would have chosen to mount it: