Author Topic: What is the maximum size large ring that will work on a Tiagra 4703 triple?  (Read 1044 times)

Shimano says only 30/39/50.

But based on past experience I know that I can usually get 22 or even 24T capacity from a Shimano triple front mech, but that the middle/outer ring gap needs to be preserved. 

Ideally i would like 28/41/52. Would that work?

It's for a tandem and I want as broad a range as possible to do both hilly-ish club rides and the odd TT. 

LittleWheelsandBig

  • Whimsy Rider
I would expect it to work. A 41t middle ring is pretty rare.  You might need to use a 40t.
Wheel meet again, don't know where, don't know when...

BFC

  • ACME Wheelwright and Bike Fettler
I have used 7703 which had 30/39/53 rings as standard (9s DA, octalink aka HollowtechI) and 7803 which had 30/39/52 rings (10s DA HollowtechII) with their corresponding front mechs - the features on the inner guide need to match the delta between the outer and middle rings to give correct upshift performance. Using GS rear mechs, double crank set ups of the era use the SS rear mechs.

 

Thanks.  I've got John at Spa on the case. 

I've just checked their site and it does look like 41T middle rings do not exist so that won't be an option.  If they don't have them I don't think I'll find them anywhere.

I think keeping that 11T gap will be the most important thing so would need to either go up to 53 or down to 51.  53 would be ideal for TTs but means I am not likely to get less than a 29T inner. I see they don't exist either, so either a 30 or, if I am very lucky, 28.
28/42/53 would be ideal, if it will work.  30/42/53 more likely to work but slightly higher bottom than we currently have. 

The other option is to just go for a double, 11-speed and an 11-40 cassette with GRX rear mech.  As I see that the options for triples are quite limited, I'm gradually re-realising why that is what I have on my own bike!  Only downside is some large gaps between the gears but I think we can both live with that.

LittleWheelsandBig

  • Whimsy Rider
Rivendell made a range of odd-toothed inner/ middle rings (Willow but made by Vuelta) in the dim dark past but those rings are long gone.
Wheel meet again, don't know where, don't know when...

Do Middleburn or the company that took them over no longer produce chainrings

I've run 26-38-50 successfully with older style Tiagra and 105 FDs
ISTRC they spec-ed an outer to middle gap of minimum 11T but 12 works too IME

I've run 26-38-50 successfully with older style Tiagra and 105 FDs
ISTRC they spec-ed an outer to middle gap of minimum 11T but 12 works too IME

Thanks Pete, that's useful. 
I recall you were a die-hard triple user!  Are you still on one? I guess not as ISTR our last conversation was about Absolute Black oval rings!

Ordered 28/40/51. 23T difference vs recommended 20.
22 works on most bikes, my galaxy has 24.
I'll find out if I can get away with it in a week or two.

I've run 26-38-50 successfully with older style Tiagra and 105 FDs
ISTRC they spec-ed an outer to middle gap of minimum 11T but 12 works too IME

Thanks Pete, that's useful. 
I recall you were a die-hard triple user!  Are you still on one? I guess not as ISTR our last conversation was about Absolute Black oval rings!

Good memory !
The AB ovals (46/30) on 105 -R7000 cranks got moved to the new carbon "Sunday best", although if both stock and funds had been available at the time, I might have gone for 48/32 ovals on that.   It does mean the Ti Audax machine has, for now at least, reverted to triple.  The 531ST Dawes Galaxy that is in use as a daily commuter through the winter months also sports a triple, although I never seem to use anything other the middle ring on that.