At 8:31 AM -0800 12/5/07, Tom Dalton wrote:
>Jan Heine wrote:
>Campagnolo's derailleurs don't have that feature. They shift
>immediately - for clean shifts, you have to let up slightly on the
>pedals. As a result of the immediate shift, you get immediate
>feedback when you move the friction shift lever.
>
>Are you comparing similar vintage Campy and Shimano stuff? Newer
>Campy is apparently just Shimano clone, with the Hyperglide (sorry,
>Exa-Drive) style ramps and the floating guide pulley. Given the
>apparent similarity in design, it's hard to imagine that the two
>systems funcction in fundamentally different ways.... or have
>I missed something? Perhaps you are comparing SIS/Hyperglide to old
>drop parallelogram Campy?
I am comparing current-generation Campagnolo with current-generation Shimano. Sorry this is OT. At least some of the bikes that I rode with this equipment were KOF.
Shimano's and Campagnolo's systems are not exact clones, no matter what people say!
Shimano enables almost silent shifts under full load, but the price is a delay between activating the shift lever and the actual shift, while the system aligns chain and ramps.
Campagnolo will crunch during full-load shifts, but the shift is immediate. (To avoid the crunch, I let up slightly on the pedals, as you did in the "old" days.)
I am sure Frank Berto could test this difference on his machine (and Shimano would come out ahead for its smoother shift), if he still had it. However, I prefer Campagnolo derailleurs - for their function, not the name - showing you that lab tests often don't replicate on-the-road experience.
I find STI's delay in shifting even more bothersome because STI allows only a single shift to a smaller cog. With a compact double and 16 teeth between rings, this makes for a difficult transition from large to small ring as you approach a steep climb: You have to shift to smaller cogs on the rear as you downshift on the front, because the front step is rather large. Depending on the cassette, you may need to shift as many as 4 cogs on the rear, for example, to get from a 50-23 (59" gear) to a 34-18 (51" gear)...
With Campy Ergopower, one sweep of the lever is all you need, in fact, you can shift front and rear simultaneously.
With Shimano STI, it is shift, wait, shift, wait, shift, wait, shift, wait. With the initial shift from 50-23 to 34-23, I need to increase my cadence within a second or two from 100 rpm to 150 rpm to keep my speed the same. (The 34-tooth ring is 33% smaller than the 50-tooth ring.) I find that hard, and so my speed drops to the point where I need another shift or two when I finally reach the "consecutive" gear. Perhaps this problem is more pronounced in Western Washington, where the recently glaciated landscape have lots of bumps, where the roads go from flat to 10% within a few yards.
For pro racers, these shortcoming of STI probably matter little. They use their big ring for most riding, and their small ring often is only 8 or 10 teeth smaller than the big one. So a front shift is 1) rare and 2) not a huge change in gear ratio, so there isn't a lot of rear shifting needed when going to the small ring.
Jan Heine
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