9 speed triple front mech replacement

[wajcgac]

I've a broken tiagra 9 speed triple front mech FD-4403 that I'd like to replace on a 20yr old bike fitted with 52T, 42T, 28T chainrings. The 28T is not an original fitting and in theory exceeds the 22T capacity but it seemed to work fine for me.

The nearest replacement spec wise that I can find is the Microshift R539 but the only place I can find it actually mentioned in the UK is Wiggle/CRC where it says 'stock expected soon'.

Is the Shimano Sora FD-R3030 a possible alternative?

It has a 50T 39T 30T spec. I coud swap my 52T for a 50T but would the then 50T/42T (outer/middle) combination I have fall foul of its applicable top mid tooth difference of 11T spec. I'll only have 8T difference, will this be an issue? I've seen comments related to other mechs that not having the required drop between outer and middle can result in the cage catching the middle ring?

Anyone been through this already with an old triple mech and have any recommendations?

[yoav]

I must admit, I've never considered the quoted tooth capacity of a front mech, just the rear mech. As long as the triple front mech's inner plate is low enough to shift the chain off the smallest chainwheel then it should work. I'm currently using an ancient campagnolo mirage triple front mech with a 52/42/28 chainset. No idea what the mech's capacity is but it works. Like yours, the 28T was not the original fitting which was 32T.