Expert advice on choice of front derailleur, please.

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Chris Jeggo
Posts: 188
Joined: 3 Jul 2010, 9:44am
Location: Woking

Re: Expert advice on choice of front derailleur, please.

Postby Chris Jeggo » 14 Jun 2020, 5:43pm

Many thanks, nsew and gaz,

for your further useful suggestions.

As soon as I have a good solution, I'll post here to let you all know what it is.

Chris

PaulS
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Joined: 26 Jan 2012, 6:45am
Location: East Yorkshire

Re: Expert advice on choice of front derailleur, please.

Postby PaulS » 6 Sep 2020, 12:09pm

Does anyone know where I can find the maximum tyre size for a (road) front derailleur? I cannot find that in the Shimano documents.

Brucey
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Joined: 4 Jan 2012, 6:25pm

Re: Expert advice on choice of front derailleur, please.

Postby Brucey » 6 Sep 2020, 12:28pm

PaulS wrote:Does anyone know where I can find the maximum tyre size for a (road) front derailleur? I cannot find that in the Shimano documents.


laterally? It depends on chainline mainly plus a few other things. The type of FD wouldn't make a very big difference.

Radial clearance is primarily about the frame geometry.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

gregoryoftours
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Joined: 22 May 2011, 7:14pm

Re: Expert advice on choice of front derailleur, please.

Postby gregoryoftours » 6 Sep 2020, 12:32pm

PaulS wrote:Does anyone know where I can find the maximum tyre size for a (road) front derailleur? I cannot find that in the Shimano documents.

Component manufacturers wouldn't be able to give you that information because it depends on too many variables to guage with any certainty, for example chainstay length, rim width and how it affects tyre width, etc. It'll be more suck it and see.

gregoryoftours
Posts: 1346
Joined: 22 May 2011, 7:14pm

Re: Expert advice on choice of front derailleur, please.

Postby gregoryoftours » 6 Sep 2020, 12:41pm

If you have a 28.6 seat tube you could also try a 34.9 band on front MTB mech but with an asymmetric shim to bring the range of the cage to suit a slightly narrower chainline. I haven't tried it but it's a thought.

https://www.sjscycles.co.uk/gear-spares ... hed-split/

PaulS
Posts: 74
Joined: 26 Jan 2012, 6:45am
Location: East Yorkshire

Re: Expert advice on choice of front derailleur, please.

Postby PaulS » 6 Sep 2020, 1:34pm

Thanks for the replies. I spotted that Campagnolo quote maximum tyre size for a front derailleur as 32mm. And Shimano say their GRX gives wider tyre clearance, but doesn't quote a limit. That got me thinking, and measuring.

https://www.campagnolo.com/UK/en/Compon ... derailleur

https://bike.shimano.com/en-EU/product/ ... 810-F.html

For my next project I would quite like wider tyres, and up to now I hadn't considered the limitations of the front derailleur. I was worrying mostly about the frame and the brakes. Tyres probably 40mm or thereabouts. Don't really want a 1x drivetrain.

Brucey
Posts: 41508
Joined: 4 Jan 2012, 6:25pm

Re: Expert advice on choice of front derailleur, please.

Postby Brucey » 6 Sep 2020, 1:39pm

GRX uses a different chainline to more conventional 'road' stuff

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

peetee
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Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: Expert advice on choice of front derailleur, please.

Postby peetee » 6 Sep 2020, 2:19pm

I have a Campagnolo 9 speed triple front mech on my everyday bike. It is running 30-39-48 rings but is designed to suit a 53 tooth as standard. Despite the 5t difference in the top ring it produces a superb, near silent shift across all the rings and doesn’t need to be set high even with a 9t ring difference between rings. Given the shift is that good I figure it could probably deal with your set up.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

PaulS
Posts: 74
Joined: 26 Jan 2012, 6:45am
Location: East Yorkshire

Re: Expert advice on choice of front derailleur, please.

Postby PaulS » 6 Sep 2020, 8:19pm

Brucey wrote:GRX uses a different chainline to more conventional 'road' stuff


Well spotted, thanks. Looks like GRX will take 42mm tyres with the double chainset.

https://www.bikeradar.com/news/shimano-grx/