front derailleur for a 46/36 or 48/36 double?

Dan Daniel said:

When you set up a double with small chainrings, is it better to use a
typical road double front derailleur, or an MTB triple? I'm looking at
combos like 48/36, 48/38, or 46/36. These all are 'in spec' for an XT
751 front derailleur (48 teeth max). But maybe a bit small for a road
double, like the older 105 I have on now with a 48/39 and working
fine?

I have no trouble with a 46/30 and a road derailleur.

--

David L. Johnson

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_`\(,_ | property, without due process of law; nor deny to any person
(_)/ (_) | within its jurisdiction the equal protection of the laws. --
Fourteenth Amendment to the U. S. Constitution.

One of my bikes is set up with 48/38 (Salsa rings on Ultegra crank, 105 front
double derailleur). Works perfectly.

Mike Yankee

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Quoted message said:

When you set up a double with small chainrings, is it better to use a
typical road double front derailleur, or an MTB triple? I'm looking at
combos like 48/36, 48/38, or 46/36. These all are 'in spec' for an XT
751 front derailleur (48 teeth max). But maybe a bit small for a road
double, like the older 105 I have on now with a 48/39 and working
fine?

This is with bar end shifters, so indexing is not an issue.

Thanks.

I have a 50/36 with the chain derailed by an old 105 front mech operated by
even older 105 friction downtube shifter, moved by an even older rider !
This setup was in place before STi came along and IMHO the operational
parameters are most significant when STi shifting is used. With friction
shifters one has plenty of fine trimming available and one can usually
overshift to force the jump - less so with STi so matching of components is
more important.

I think most road doubles are designed with a curvature for a big ring
at least 50T. That said, if you can get the derailer low enough without
it hitting the chainstay, it will work with smaller rings. I use a road
double to shift a 44x29 combo on my touring bike.

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