Moulton Front Derailleur Adjustment

[igauk]

Since I acquired my new to me Moulton TSR 30 I've been going round in circles trying to get the front derailleur adjusted correctly. When I got it it was overshooting changing up into the big ring. Simple I thought, tweak the limit screw. Except I couldn't find a sweet spot, it either overshot or didn't change up. Went back to basics and started from scratch. I think I've now gone through every possible combination of height, limit screw adjustment and cable tension. This is with a Campag Chorus triple (56, 42, 30), Centaur QS shifters, Comp Triple FD, Centaur RD, 10 speed 11-23 cassette. The rear shifts fine, the chain isn't worn and there's no play in the bottom pivot. I'm about to put a new cable on it, in case that's a problem, but before I do a couple of questions.

1) The cable clamp on the FD has a 'pip' on it - the cable is currently clamped over the top of this, is this correct?
2) I've noticed Moultons seem to have their FD set higher than the usual 1-3 mm above the outer ring - does this help? (it didn't seem to when I tried it, I got overshooting and chain rub!)
3) Any secrets to this?

Thanks

[pwa]

Have you tweaked the angle. as viewed from above?

[igauk]

Yes, even tried it slightly out of alignment.

[pwa]

Maybe it is related to having a 56t chainring, which sounds a bit larger than usual. I know why they do it, with the small wheels, but I wonder if that is the root of the problem. Maybe the FM cage is shaped for more like 52.

[Mick F]

Hi, I'm another TSR30 owner!

Mine came with a Stronglight 58/48/34 triple and Shimano Tiagra derailleurs.
The braze-on is set too low, so the Tiagra front mech was right at the top, also the mech was originally maybe 10mm above the big ring.
First thing I did was to lower the mech so it was set 1mm above the big ring in accordance with the instructions.
Trouble was, the front mech cage is quite deep, so when changing to middle ring, the mech inner plate caught on the middle ring!
That's why the mech was set too high.
Being high, it seemed to work ok, but very very hit and miss if it worked nicely or not. Very crunchy changes and I had to be patient with it.

Main problem with the TSR is that the braze-on is not variable enough. It's a standard braze-on on a non-standard tube. Moulton would have been better to have designed a clamp-on unit that could be moved and adjusted to cope with a wide triple.

The Campag Comp Triple front mech I have on Mercian has a pip and a slot to hold the cable under the washer. The cable goes ABOVE the pip.

Secrets?
Loads of them with Moultons.

I sold the 58t outer and bought a 61t instead. With some jiggery-pokery and the help of an engineer I designed a unit to bolt onto the braze-on to hold the front mech in a better position. Also, by having a 61/48/34 the front mech can be set close to the outer ring and still clear the middle one. Front changes are perfect now.

[igauk]

It's possible pwr, but as 56 teeth (and up) are fairly common on Moultons I would have thought the FD could cope

[pwa]

It's possible pwr, but as 56 teeth (and up) are fairly common on Moultons I would have thought the FD could cope

And four extra teeth over normal isn't going to make the circumference much bigger. It could explain why you have noticed the mech being a little high on Moultons, though, to get the tail of the cage high enough perhaps.

[igauk]

Thanks Mick F. I've a spare 58 ring, so maybe going even bigger with a high set FD will do the trick! I noticed the SST version has a re-designed front mech mount, good of them to fix the problem - 10 years later! I like a fettle but this Moulton is straying dangerously close to complete PITA territory.

[Mick F]

The front mech inner plate needs to be parallel with the chainwheels and set as low as possible. Campag state that the outer plate should be 1mm above the outer ring.
The cable should be above the pip and clamped tightly with the cable along the slot under the washer.
The limit screws should be set so the chain doesn't overrun off the outer ring, or underrun off the inner ring.
If it's like that, you can do no more.

-------------------------------------------------------------
Don't forget about the rear suspension pivot or the front suspension bushes. All need regular maintenance.

Moultons - especially the TSR - are definitely in PITA territory, but great fun.

[Brucey]

42-56 is a larger than normal interval and may be part of the problem. The shift onto the big ring will be a touch baulkier and by the time it goes, it may be in a mood to overshoot.

If you are all out of ideas then I'd suggest a 46T middle ring (and maybe a larger inner ring to match it).

cheers

[Mick F]

58/48/34 for the original TSR that I bought.
Now a 61/48/34 and far better for it. Mind you, I'm on DT shifters now so they may be more sympathetic.

Changes are good and reliable and I don't worry about it at all.

[igauk]

Thanks all, I'll tinker tonight and update. A 48 middle ring wouldn't be bad idea.

[igauk]

I got just about acceptable shifting with the FD as low as possible, literally a hair's breadth clearance on the outer chain ring, parallel alignment. Still not entirely happy with it but it'll do for now. I take it a TA outer chain ring can be reversed and fitted to the middle if I go down the 48 tooth middle route?

[fossala]

I've owned quite a few Moultons and rode a few that wheren't mine, non of them had good front shifting. I believe this is because of the larger chainrings and the front mechs aren't made for them. I never managed to get one set up that would never drop or overshift once in a while.

[hercule]

Moulton sell (or used to) a threaded aluminium spacer that fits between the mech and the braze on. This has the effect of mounting the mech further back and a bit lower down and seems to make normal sized front mechs work better with over sized rings. It works fine on my AM with an Ultegra double front mech and a 62T chainring.

Bear in mind what Moulton prices are like though.... DIY might seem better if you know someone with a milling machine!