going double to triple

[Eden]

hmmmmmm it looks like you could possibly order that crank with a 52 outer and 24 inner, but I would think that would not be such a good idea. With a difference that great in the rings shifting would be a real bear... you'd really be pulling hard to get the chain up from the small ring to the big one and when you shifted down the drop would be so big that you'd probably drop your chain a lot... I'm looking around for the biggest suggested difference between inner and outer rings.

[SadieKate]

The rule of thumb I've been given is 10-12 tooth max difference between rings for the snappiest shifting. This is part of the reason there was a real lapse in the performance of shifting on compact doubles, the 16 tooth jump. Until recently many front derailleurs just weren't designed for this gap, hence the intro of derailleurs designed for compact doubles.

[Eden]

I have doubts that a 28 tooth difference would shift at all.... on my old bike with a triple it was *hard* to shift from the 30 to the 42 and that's only a 12 tooth difference.

[SadieKate]

I went back and noticed that the drivetrain is Campy. Definitely stick with 10-12 tooth gaps max.

Look at a nice polished Sugino triple with 46-36-26. This should give you a nice set of climbing gears while still maintaining the tight cogs set for flat land riding. You will need a new bottom bracket but you can get some nice quality JIS taper BB's for a reasonable price.
http://www.sheldonbrown.com/harris/cranks/11074.html

For upscale cranks, you can look at TA cranks from Peter White and customize the ring choices even more.
http://www.peterwhitecycles.com/carmina.asp

Here is info on calculating your derailleur capacity
Chain Capacity and Cage Length
http://branfordbike.com/page.cfm?pageID=62

[SadieKate]

I have doubts that a 28 tooth difference would shift at all.... on my old bike with a triple it was *hard* to shift from the 30 to the 42 and that's only a 12 tooth difference.

Yeah, typically the smallest ring to the middle ring should only be 10 while you can go to a 12T gap between middle and big.

[SadieKate]

Don.t forget you would have to change your shifter also.

Why?

Most Campy shifters (not 11 speed) are both double and triple compatible.

And Campy triples shift most excellently.

[aicabsolut]

Here's a Campy 50-34 crankset:
http://www.excelsports.com/new.asp?p...jor=1&minor=13

[wnyrider]

Well, I just purchased a campy 13-29 cassette. I can't tell you how I fretted over choosing which component to swap. There was no definitive answer, and that is what I was bugged about. Thank you all for your input. It was appreciated. The least $ route was to go with a new cassette and the LBS will swap it for me, but I want to be there so I can see how it is done for future reference. It'll be at least a week before I'll be able to test it out... I'll report back on the result.

[added: It has been 2 months and I still haven't chosen clipless pedals yet!!]

[wnyrider]

Here it is October and the company I ordered from has called twice stating the cassette is still on backorder, waiting for delivery from Italy. I checked with several other companies and they don't have that particular getup in stock either. At this point, even if I find the cassette available, I will pass. I am nearly ready to put the bike away for the winter-- no point in making the transition if I can't test it out comfortably in the elements. I suppose it could make for a winter project, but my enthusiasm has waned. I shall ready my cc skis instead!