Cycling UK Forum

I have a Dawes Audax bought new about 18 years ago that is very much a second bike these days, but a nice thing none the less. A couple of weeks ago I decided to take it out, but before long I lost front changing. An inspection revealed that the spring retainer seems to have broken off the front mech, which is Tiagra. A search for a replacement found advertised an old stock Ultegra mech that specifically stated triple 9 speed and 52 teeth maximum. However when it arrived it looked quite different from the Tiagra and on fitting it I found that because it has a ridiculously wide backplate it won’t pass the second chainring if mounted at a sensible height.
Any ideas what would work as a replacement? Paying more attention this time, I’ve found a Claris triple that looks similar to the old Tiagra (normal backplate) but it does state that it is for 8 speed. Would that be a problem or only when extreme cross chaining?
The brifters are 105 by the way and the chainset is Truvativ.
I assume road tourers with triples and relatively large chainrings are still made? If so what do they use?

I have a similar set up and run a 9 speed Campagnolo triple mech and it shifts beautifully with no compatibility issues whatsoever.

peetee wrote: ↑22 Mar 2022, 7:06pm I have a similar set up and run a 9 speed Campagnolo triple mech and it shifts beautifully with no compatibility issues whatsoever.

That sounds hopeful - thanks. I’ll extend the width of my search.

Altus is also a 9 speed option but fairly deep back plate too.

FOSS62 wrote: ↑22 Mar 2022, 6:56pm I have a Dawes Audax bought new about 18 years ago that is very much a second bike these days, but a nice thing none the less. A couple of weeks ago I decided to take it out, but before long I lost front changing. An inspection revealed that the spring retainer seems to have broken off the front mech, which is Tiagra…

… Any ideas what would work as a replacement?

Did you find a suitable replacement?

Can you grind the backplate to suit?

If the only problem with readily available mechs is the deep inner plate touching the middle ring, is it possible to just raise the mech so it doesn't do that? I know they say the mech is supposed to be 3mm above the big ring, but you can get away with more than that if it helps.

I have one of these Sora mechs (with adapter) on my 9 speed tourer and it works well. But the inner plate is deep.https://spacycles.co.uk/m8b0s106p3679/S ... Front-Mech

What rings are you using? Mine are something like 26 / 36 / 48.

You don't say what you mean by "relatively large chainrings". What is your crankset?

Mine are 48-38-26. My current FD is an Ultegra FD-6503. https://si.shimano.com/pdfs/si/SI-53H0B-000-00-ENG.pdfIt works perfectly with my chainrings. It's actually intended to be used with slightly larger chainrings - https://si.shimano.com/pdfs/si/SI-16T0B-000-ENG.pdf. My FD is set at the recommended height above the large chainring. The curve of the plate is obviously intended for a slightly larger chainset, but I don't have any problems whatsoever.

In the past I've also used the 105 FD from the same era, FD-5504 https://si.shimano.com/api/publish/stor ... 4-2174.pdf which was also fine.

I've also used the current Sora triple FD - https://bike.shimano.com/en-EU/product/ ... 030-F.html which was also fine, even used slightly outside it's spec.

I'm non plussed as to why you haven't been able to set the Ultegra FD up. You say nine speed and it's got a "ridiculously wide backplate". I assume you mean deep, from top to bottom? That isn't ridiculous, it's by design, so the thing works.

I wonder, are you aware that there is usually a minimum difference between middle and outer rings that a front derailleur is designed for? You can see what that is if you look at the specs for the crankset that matches the derailleur. The FC-6503, for instance is 52-42-30. That's the matching crankset for the FD-6503, so that derailleur is expecting a difference of 10 teeth between outer and middle. Anything less than that you may start to have problems.

You reference touring bikes, so a good place to look would be Spa Cycles. I don't know what you mean by "relatively large chainrings" but relative to sports cycles, touring cycles actually have smaller chainrings, usually. But relative to mountain bikes, larger ones.

For a good idea what works, look at Spa's builds:

https://www.spacycles.co.uk/m1b0s225p38 ... S-Wayfarer

LancsGirl wrote: ↑6 Apr 2022, 9:20am You don't say what you mean by "relatively large chainrings". What is your crankset?

Mine are 48-38-26. My current FD is an Ultegra FD-6503. https://si.shimano.com/pdfs/si/SI-53H0B-000-00-ENG.pdfIt works perfectly with my chainrings. It's actually intended to be used with slightly larger chainrings - https://si.shimano.com/pdfs/si/SI-16T0B-000-ENG.pdf. My FD is set at the recommended height above the large chainring. The curve of the plate is obviously intended for a slightly larger chainset, but I don't have any problems whatsoever.

Interesting observations. Just to add my experiences with a very similar set up.
I run 48/39/30 Dura Ace 7800 triple set. The only substitution being that 48 ring; standard is, I believe, 53. The mech has to be set ‘too high’ to clear the middle ring but performs faultlessly.

peetee wrote: ↑6 Apr 2022, 10:52am

LancsGirl wrote: ↑6 Apr 2022, 9:20am You don't say what you mean by "relatively large chainrings". What is your crankset?

Mine are 48-38-26. My current FD is an Ultegra FD-6503. https://si.shimano.com/pdfs/si/SI-53H0B-000-00-ENG.pdfIt works perfectly with my chainrings. It's actually intended to be used with slightly larger chainrings - https://si.shimano.com/pdfs/si/SI-16T0B-000-ENG.pdf. My FD is set at the recommended height above the large chainring. The curve of the plate is obviously intended for a slightly larger chainset, but I don't have any problems whatsoever.

Interesting observations. Just to add my experiences with a very similar set up.
I run 48/39/30 Dura Ace 7800 triple set. The only substitution being that 48 ring; standard is, I believe, 53. The mech has to be set ‘too high’ to clear the middle ring but performs faultlessly. 3A8EEA32-9509-4B55-B533-61172BC27B50.jpeg

(large chainring in DA triple 10 speed is actually 52, I think)

Yes, that is to be expected. You've got a 9 tooth difference, outer to middle, whereas that derailleur is expecting a difference of 13 teeth.

https://si.shimano.com/api/publish/stor ... 00-ENG.pdf

So your difference is 3 teeth "too few". Each extra tooth adds 2mm to chainring radius, so your 3 teeth too few means that you've had to set your derailleur 6mm higher to be in the same place that it would be if you had a 52 tooth chainring (which is what it expects).

That looks about right, yes? Maybe not quite 6mm higher, but certainly higher than usual.

EDITED for maths.

What other size chainring is the OP using, 52/?/?, as it will help to know.
A "road" triple mech works with a min 10t difference and a "MTB" works with min 12t.
If you've less then you ....
Either need to set the mech slightly high to clear the middle ring.
Or change to a "road" double that doesn't have a deep backplate and hope it covers the range of movements needed.
Or even find a secondhand triple mech of the right vintage that will work with less than 10t difference.

Luck............

LancsGirl wrote: ↑6 Apr 2022, 11:20am [

(large chainring in DA triple 10 speed is actually 52, I think)

Yes, that is to be expected. You've got a 9 tooth difference, outer to middle, whereas that derailleur is expecting a difference of 13 teeth.

https://si.shimano.com/api/publish/stor ... 00-ENG.pdf

So your difference is 4 teeth "too few". Each extra tooth adds 2mm to chainring radius, so your 4 teeth too few means that you've had to set your derailleur 8mm higher to be in the same place that it would be if you had a 52 tooth chainring (which is what it expects).

That looks about right, yes? Maybe not quite 8mm higher, but certainly higher than usual.

Indeed. Just including this as the set up on one of my bikes and it’s worth noting my previous post about substitution of a Campagnolo mech. Much the better arrangement, IMO, as the absence of specific tooth-count-related ramps on the mech plates makes it a far more versatile choice.

The "deep backplate" is a modern contrivance designed to make the shift "foolproof" for modern cyclists who expect everything to change under pressure.
Previous incarnations of front mech. relied on the rider easing off the pressure on the pedals for half a turn in order for the change to proceed, and didn't need to be so complex, and had the advantage of working as well (or as badly ) with a range of chainwheel sizes.

Long ago, I silver soldered a bit of stainless to extend the outer plate of a F. mech. cage to suit a "smaller than designed" big chainring, paired with a "design" middle chainring. It worked OK, but then I don't expect it to change under pressure!

DSC00237_0009 by 531colin, on Flickr

Long time since i've seen a Romany, whats the story with the 'wrong' side front disc?

bear with me on this; my recollection isn't that clear......
I have an original rim brake 853 Romany; in fact, I have the one which went out to the magazines for testing.....I got it a bit cheaper as it was "used".
I think a pal had a subsequent Romany with disc brakes, which would have been a similar class of bike? Light blue?
That one in the picture is a wholly different animal. It was built for rim brakes; I put disc brakes on it because I wanted to try them on the cheap, and I put the front one the "wrong" side because people worried about the brake pulling the wheel out of the dropouts.
It wasn't a success, I think the brake was too far away from the fork, and/or the fork was too flexible; in any event it was OK in the dry, but as soon as I got into cloud (not difficult off road in the Dales) the brake simply howled and didn't slow me down. I guess the pads were alternately gripping and slipping on the disc as the caliper mount flexed? Back brake was fine, I think I mounted it to both seat and chain stays.
I think they were some cheap frames that Simon had bought up maybe as a job lot, and he was flogging them off. It was about the time that Orbit was getting into difficulties, and those frames wouldn't have helped.....it was an awful, leaden thing to ride, my lasting impression is of "crashing through the potholes"....there was nothing nice about the ride at all, and the bottom bracket was ridiculously low, I got pedal strike just riding on uneven ground.
All down to experience!