Smaller Chainrings with Shimano FD

[NetworkMan]

I'm in the process of updating/rebuilding my 2001/2 Dawes Audax which is mostly 9-speed Tiagra SIS 4400 series.
I've done bars, stem and tyres and am now doing chainset which entails reducing the chainrings from 52/42/30 to 48/38/28 initially. Because I might want to go smaller still later I'm fitting a Spa TD2 110bcd chainset which handily needs the same 113mm bottom bracket as the Shimano FC-4403 130bcd one which I'm swapping out.

The question concerns the FD-4403 mech. which is intended for 52/42/30 and I'm changing to 48/38/28. In his "Beat the System" article, CJ says that this change should just about be OK since the front difference is the same and the 4T change in size is the maximum he recommends.

I wonder if anyone has done a similar change and if so did the front indexing/changing still work OK?

If not I could buy a modern Sora 9-speed FD which is intended for 50/39/30 which looks like a better match, with a max. 2T difference rather than 4.

I'm asking this question now because bike-discount.de have a special offer on a Sora triple mech at £8.18 https://www.bike-discount.de/en/buy/shi ... 9mm-477854

and a suitable shim at £1.38 https://www.bike-discount.de/en/buy/shi ... ount-36909

Of course if I used this mech. I'd still be using my old ST-4400 shifters, not the new ones, but I suspect that this may not matter too much.

Any views appreciated.

[meic]

Dawes themselves did this at some point in their production.

https://www.thebikelist.co.uk/dawes/galaxy-2011

A Deore MTB crank rather Spa 110bcd but still smaller chainring sizes than standard Tiagra, while retaining a Tiagra front derailleur.

It was in one of the old CTC mags and I seem to recall that CJ praised them for the slight deviation from the norm.

[NetworkMan]

Dawes themselves did this at some point in their production.

https://www.thebikelist.co.uk/dawes/galaxy-2011

A Deore MTB crank rather Spa 110bcd but still smaller chainring sizes than standard Tiagra, while retaining a Tiagra front derailleur.

It was in one of the old CTC mags and I seem to recall that CJ praised them for the slight deviation from the norm.

Yes it can be done but that mech. is 10 years newer than mine.
Spa use a new 9 speed Sora on their tourer with 48/38/28 so I could probably make that work. They have modern shifters too of course.

PS
Thanks for that meic. It got me looking around and I realised I had a Dawes 2003 catalogue. The 2003 Super Galaxy had a 48/26/26 chainset and a 9 speed setup with Tiagra front derallieur. Unless the 2003 Tiagra changer is significantly different from mine it's highly likely that I can make it work. Probably no need to buy a newer changer.

[meic]

I see your point and a mech aimed at 50/39/30 would probably be better suited than one aimed at 52/42/30.
I have always avoided 105 on those grounds.
I do have a Tiagra 4603 because they were intended for 50/39/30 and I failed to spot you said 4403.

However I would certainly give the existing FD a try and only replace it if it didnt work.

[NetworkMan]

Meic,
See my edit - our postings crossed. Thank's again.

[meic]

I havent got the facts totally straight in my head but when setting up a FD with mismatched chainrings, you dont always choose to set it up based on a gap from the outer ring.
Sometimes it is better to set it up based on the middle ring, a bit higher than you would choose based on the outer ring.
So 52-42-30 is a 4 tooth change to 48-38-28 and 50-39-30 could be more like a 3 tooth change, than a 2 tooth change.

[NetworkMan]

Yes, it's unclear to me too - suck it a and see I guess. The newer Sora mech looks different from my old Tiagra; much deeper on the inside face. Whether that would be help or a hindrance to a mismatch of rings I've no idea!

[Brucey]

I think your original FD will be fine because the intervals are similar. Using an FD that is meant for (say) a 13T interval is unlikely to work anywhere near as well, IME. Even an 11T design interval on a 10T interval leaves the FD slightly higher wrt the outer chainring.

cheers

[freeflow]

I've been happily using ultegra 6603 and 6703 front mech with a 44/32/22 xt chainset since Jan 2015. The front mech sits about 10 mm above the 44 tooth chainring due to chainstay clearance.

You need a slight pause between each click of the left hand shifter otherwise about 1%of the time the change is very graunchy.

The riding I've done on this setup has been extensive, including a double Audax ratty in 2015/6

[NetworkMan]

Many thanks to all for the help. The cranks and rings will arrive on Monday so we'll soon see....
Lovely new Kinlin XR22T wheels for the Spa tourer too so very exciting!

[Sweep]

Great choice on the chainset. They are right when they say in the blurb that it is classier looking than the price suggests.

One thing.

Here:

https://www.spacycles.co.uk/m2b0s109p20 ... e-Chainset

it seems to say that you need a 110mm bottom bracket

though I have an idea in the back of my head that perhaps when I fitted it there was some confusion(at least in my own head) as to whether it should be 110 or 113mm.

[meic]

You may be thinking of the other version the TD2 which is 113mm
https://www.spacycles.co.uk/m2b0s109p30 ... cral-Rings
equivalent to this Stronglight which uses a 115mm.
https://www.spacycles.co.uk/m2b0s109p28 ... act-Triple
Or the double version of one or the other.

[NetworkMan]

Great choice on the chainset. They are right when they say in the blurb that it is classier looking than the price suggests.

One thing.

Here:

https://www.spacycles.co.uk/m2b0s109p20 ... e-Chainset

it seems to say that you need a 110mm bottom bracket

though I have an idea in the back of my head that perhaps when I fitted it there was some confusion(at least in my own head) as to whether it should be 110 or 113mm.

I have the XD-2 on my tourer but I'm getting a TD-2 for the Dawes Audax because it needs 113 mm not 110 mm. Having said that there is a confusion in that the correct axle must depend on whether the rear wheel is 130 or 135 mm. I suspect that the XD-2 110 mm. is correct for 130 mm and that for 135 mm it should be about 113 mm since the sprockets move out by 2.5 mm.
I'm happy with 110 mm on the tourer because if it is wrong it's biased slightly towards the lower gears which I use more and in any case the difference is only about 1/2 a rear sprocket pitch. I did wonder about swapping bottom brackets and buying another XD-2 but I think the TD-2 actually looks prettier. A TD2 plus the two larger rings costs about the same as a complete XD-2 and I already have a 28T.

Edit.
Now I'm confused since a 3 mm longer axle only moves the rings out by 1.5 mm. We'd need an axle 5 mm longer to account for the difference.

[Sweep]

thanks for your post networkman.

Will be taking the BB out soon and will check just what I ended up putting in there.

The bike is a 90s steel hybrid.

I do have an intermittent issue with dropping down to the bottom ring.

It's possible that your post points to a resolution.

[NetworkMan]

It's too late in the evening for me! Goodnight!