54,55,56 tooth big ring with Ultegra fr.der?

Quoted post said:

Originally posted by 02DeRosaV
Hi,
I am contemplating a switch to either a 54, 55, or 56 tooth big ring. Has anyone had success in using an Ultegra front der. with this setup? BTW, I am using an old-style 39/53 D-A crank. Thanks!!

What else would you use? If the frame uses a braze on FD make sure you can get it high enough.

Quoted post said:

Originally posted by 02DeRosaV
Hi,
I am contemplating a switch to either a 54, 55, or 56 tooth big ring. Has anyone had success in using an Ultegra front der. with this setup? BTW, I am using an old-style 39/53 D-A crank. Thanks!!

The spec for Shimano front road der. is 15T difference. You may not get very good shifting performance with a 39/55 or 39/56. My brother runs 42/55 on his 650C-wheeled tribike with Ultegra drivetrain.

Quoted post said:

Originally posted by Gonzo Bob
The spec for Shimano front road der. is 15T difference. You may not get very good shifting performance with a 39/55 or 39/56. My brother runs 42/55 on his 650C-wheeled tribike with Ultegra drivetrain.

That 'spec' gets exceeded all the time,and if not by excesive amounts,there is no downside. But right if someone needs a 56 they probably don't need a 39 to go with it.

A few years ago I occasionally used a 39/55 set-up with Ultegra 600, and had no shifting issues at all.

Any possibility that the bigger chainring could max out the RD, boudreaux? e.g. if there's already like a 12-27 cassette on there and a short cage mech.

Quoted post said:

Originally posted by mjw_byrne
Any possibility that the bigger chainring could max out the RD, boudreaux? e.g. if there's already like a 12-27 cassette on there and a short cage mech.

Well, a 56/39 and 12/ 27 is 32 teeth and 9 speed shimano RD are speced for 29 teeth. Again, spec is conservative.I got one speced for 26 that wraps 32. Somehow, I think a preson considering a 56 is not using a 27, and even if they were all one has to do is stay out of the smaller cogs when in the small ring,assuming there are wrap issues to begin with.

A 56/39 works fine.

Thanks for all the help....I have a 12-25 cog by the way. I'll probably end up going with the 55 just to be safe (that 56 sounds scary anyways).

You need a 55 or a 56 and you dont use an 11 on the cassette????????????????????????????????????????????

Quoted post said:

Originally posted by mrowkoob
You need a 55 or a 56 and you dont use an 11 on the cassette????????????????????????????????????????????

I´m sorry i´ll try to be more specific. One cog on the cassette equals 4 on the chainring so upping from 53 to 55 means upping from 12 tó 11.5 get it?
53-11 is the same as 57-12

I've used a 55/39 setup with several different cassettes (12/25, 11/23, 11/21), depending on the course, and had no problems.

You also need to realise that once you put a larger chainring on then you get greater effective spacing between gears. The ratios will not be as close any more.

Quoted post said:

Originally posted by tafi
You also need to realise that once you put a larger chainring on then you get greater effective spacing between gears. The ratios will not be as close any more.

D'oh?