As you say, a triple, or even a very wide range double, can drop a chain, although this is seldom a problem with an experienced tourist. On a wide range front setup one is most likely to drop the chain when shifting to the smallest ring. The same is probably true of all front setups. One can of course drop the chain outside the largest ring, but that is usually due to an incorrectly set FD outer stop sdjustment. And one can sometimes drop the chain between rings, but that is usually because the spacing between rings is too large or because of really poor shifting technique.
The tendency to drop the chain when shifting to the smallest ring can be caused but an incorrectly adjusted inner stop, but even if the adjustment is correct,one can drop the chain, especially, as you say, when shifting quickly. It is my experience that this is due to causing too much momentary slack in the chain. A triple can be pretty slack on the inner ring/outer cog combo anyway, as even with a long cage RD there must often be a compromise between handling a large outer ring for downhills while not having the chain too slack on the small-small combo. This is made worse the wider the range is, so a 52-28 front will tend to have more slack than a 50-32. I think the problem dropping chains comes when one suddenly introduces slack when shifting to the smallest ring. Not only is the inner ring gear shifted to likely to have a somewhat slack chain, but the chain is momentarily much slacker yet, until the RD cage takes up the slack introduced by the front shift. With the momentarily excessive slack it is very easy for the chain to deflect enough to drop off inside the inner ring. And the faster you make the front shift, the less time the RD has to retension the chain.
At my previous job in Texas, I had a mostly flat commute with one very steep climb. Approaching the climb I would usually be on the large ring and the middle cog or even one cog smaller. I would then shift to the smallest ring and largest cog for the climb. My normal tendency was to shift to the smallest ring first, then make the rear shift to the large cog. But doing this I experienced several dropped chains, including one that jammed between the crank and BB and proceeded to snap in half a perfectly good Campy Rally RD. The experience of destroying a rather expensive RD motivated me to analyze the problem. I came to the conclusion that by shifting to the smallest ring with the chain still on a middle to outer cog increased the extent of the momemtary slack in the chain, whereas if I shifted to the largest cog first, the tension on the chain would be higher when I started the front shift, and the chain would not become as slack during the shift. After adopting the technique of making the rear shift first, I don't think I dropped another chain.
There are devices called "chain minders" or some such that clamp to the seat tube and provide a "lip" just inside the small ring to prevent the chain dropping. I have one of these but have never installed it, as it seems rather an admission of defeat that one cannot solve the problem with proper equipment adjustment and shifting technique.
Regards,
Jerry Moos
Tuscaloosa, Alabama, USA
> From: Steve Whitting <ciocc_cat@yahoo.com>
\r?\n> Subject: Re: [CR] Dawes Red Feather bike
\r?\n> To: "Peter Brueggeman" <4peebee@peterbrueggeman.com>, haxixe@gmail.com
\r?\n> Cc: classicrendezvous@bikelist.org
\r?\n> Date: Saturday, February 6, 2010, 10:50 PM
\r?\n> My (albeit limited) experience with
\r?\n> triples as a bicycle mechanic in the mid 1970s was that the
\r?\n> better front derailleurs available at the time could handle
\r?\n> them well enough, but not necessarily under fast-shifts
\r?\n> where they'd often drop the chain off the chainrings.
\r?\n> Maybe acceptable for a tourist, but not something a
\r?\n> competitive cyclist wants to contend with in a race.
\r?\n> If you live in flat country (as I do), the need for a wide
\r?\n> range of gears sort of goes out the window. My pre-1983
\r?\n> Ciocc has a 47-inch low gear - plenty low for this neck of
\r?\n> the woods even for a 55 year-old fart like me.
\r?\n> Footnote - more gears aren't necessarily better if the
\r?\n> resulting combinations are duplicates or
\r?\n> hard-to-get-to-extremes.
\r?\n> Steve Whitting
\r?\n>
\r?\n> "The Ciocc Cat"
\r?\n>
\r?\n> Prairieville, Louisiana USA
\r?\n>
\r?\n> Website at http://ciocc-cat.angelfire.com/
\r?\n>
\r?\n> --- On Sat, 2/6/10, Kurt Sperry <haxixe@gmail.com>
\r?\n> wrote:
\r?\n>
\r?\n> From: Kurt Sperry <haxixe@gmail.com>
\r?\n> Subject: Re: [CR] Dawes Red Feather bike
\r?\n> To: "Peter Brueggeman" <4peebee@peterbrueggeman.com>
\r?\n> Cc: classicrendezvous@bikelist.org
\r?\n> Date: Saturday, February 6, 2010, 4:13 PM
\r?\n>
\r?\n> What's up with so many English bikes not fitting front
\r?\n> derailleurs?
\r?\n> Seems like an odd choice to say the least, needlessly
\r?\n> limiting the
\r?\n> practical utility of the bike. I guess they wanted to make
\r?\n> them look
\r?\n> like TT racers.
\r?\n>
\r?\n> Of course I never understood double chainrings when three
\r?\n> would serve
\r?\n> 99% of riders better for the same reasoning.
\r?\n>
\r?\n> Kurt Sperry
\r?\n> Bellingham, Washington
\r?\n> USA
\r?\n>
\r?\n> On Sat, Feb 6, 2010 at 1:07 PM, Peter Brueggeman
\r?\n> <4peebee@peterbrueggeman.com>
\r?\n> wrote:
\r?\n> > A "Red Feather" Dawes on UK eBay.
\r?\n> >
\r?\n> > http://cgi.ebay.co.uk/
\r?\n> >
\r?\n> > or http://tinyurl.com/
\r?\n> >
\r?\n> > Nice seat tube graphics! You can see those
\r?\n> interesting pump pegs mentioned,
\r?\n> > which doubled as brake cable stops.
\r?\n> >
\r?\n> > Peter Brueggeman
\r?\n> > La Jolla California USA
\r?\n> > 4peebee(at)peterbrueggeman.com