Sheldon Brown wrote:
>
> Jim Flom wrote:
>
> > I'm thinking that for racing, sheldon's guideline of threading the chain through the large-large
> > combination (apart from the der) and adding a link would leave the chain too short for racers,
> > who will find themselves in the large-large combination from time to time.
>
> What are you basing this on? What problem do you imagine will occur?
>
> > Is there another suggestion for racers?
>
> Actually, racers are less likely to do this than beginners are, 'cause a fair percentage of racers
> have a good understanding of how to use their gears most efficiently.
Well sure experienced racers will know it is not favorable, but that doesn't mean it doesn't happen,
and quite intentionally at that. Racing is reactionary unless you are the one initiating. That means
double shifts are sometimes forgone in practice in favor of the simpler and usually brief chain
crossing. The key is the briefness -- if a low gear is anticipated for a more lengthy time, there
will be a lower incentive to cross. Also, if the road is known/seen and by that it is known that the
cross will be brief, then crossing will often be chosen over the cost of two double shifts and the
possibility of dropping the chain -- which is a really bad thing to do at any key time in a race.
Insurance is worth the cost of crossing and racers do it from time to time as a concious choice.
I recognize that you never said racers *won't* do it (and beginners are sure to do it!), but I
wanted to point out that it happens in racing and training for racing with fair frequency. I almost
never cross my chain on fred rides. But for certain training ride courses and races, I do cross
(big-big) the chain quite conciously. I can't say I like doing it, but I do it.
Look at Eric Wohlberg at last year's Cat's Hill Crit (he was on fire -- he lapped the field solo and
then dropped them again), which has a 23% grade. He big-ring'ed and crossed the chain *every* lap
for the main purpose of simple gear selection and avoiding the dropped and mangled chain that is so
*common* at that race.
http://www.shutterfly.com/os.jsp?i=67b0de21b303fc45c43d
http://www.shutterfly.com/os.jsp?i=67b0de21b3030e1f452e
I was standing right beside the photographer at the top of the hill. Personally, I use a 53x46 w/ a
12-24 cassette for that race and I do change rings for the hill.
> My bikes that have double chainwheel setups are set with the chainline biased to permit use of all
> rear sprockets with the big ring, and that's how I set my chain length.
>
> Big/big is much less damaging than small/small.
You mean for your special setup?