No matter what brand of components you prefer, when even the
top pros can be seen stopping to put their chain back on (remember Andy Schleck
a few years ago at LeTour?) it’s clear that “operator error” plays a big and frustrating
part in this unfortunate situation. Here’s how you can avoid it.
You might say, “but wait, with the new electronic systems
available now, I should be able to shift to any gear at any time, the
tiny computer will certainly make things happen perfectly”, but you’d be wrong.
Nothing is foolproof as even top pros, riding the most carefully set up and
maintained machines in the world, (yes, even those with electronic controls)
can make even the best systems malfunction.
The biggest mistake we see, even from seasoned riders, is
the classic failure to anticipate the need for a lower gear. Remember that
front shifting systems (aside from the ill-fated Browning of the late 80's) despite their
pins, ramps and profiled teeth, really just push the chain off the big ring so
it can (one hopes) simply fall down onto the smaller one. This worked pretty well
when differences amounted to only 10 teeth or so, as in the old standard 42-52
setup.
With modern 39-53 or 34-50 chainring pairs, the difference is much
greater. Differences of 14 or 16 teeth are a big challenge, especially when
tension on the chain is high as you struggle up a climb in a too high gear.
Get a gear chart, then count the numbers of teeth on your
rear cogset. All of the cogs. Then write down the development when combined
with each of your front chainrings. You’ll no doubt notice that the 53 (or 50) combined with
your largest rear cog is a similar ratio you could enjoy with the 39 (or 34) chainring and one of the smaller cogs. Using the smaller chainring will do two
things; First, it will make your drivetrain more efficient as chains prefer to
run in a straight line rather than “cross-chained” at the huge angle
required by using the largest cog and largest chainring. Greater efficiency is
realized too when the spring tension on the rear pulley cage is not as high as
when using the “big-big” combination. Of course you also want to avoid the
“small-small” combo though spring tension is not an issue in this case.
Think of driving your car at highway speeds and
suddenly jamming the transmission into first gear. You probably avoid this when driving,
but many riders do the equivalent while cycling. When you ride along in the
large chainring and shift only up the rear cogset as the climb steepens, when
you eventually need a lower ratio you then are faced with the same situation as
abusing your car’s transmission. There’s only ONE shift you can
make, asking the highly tensioned chain (both from your pedaling forces and the
derailleur spring tension in that “big-big” combo) to fall off the large
chainring onto the smaller one. Even electronic systems can drop the chain
under these conditions and we’ve seen it happen... even to the pros.
Plan your shifts - instead of running the chain all the way up the rear
cogset in the large chainring, try shifting down to the small one and moving
the chain down a couple of cogs to get a similar ratio. This way you’ll easily
be able to shift into a lower gear if needed OR go back to the larger
chainring if necessary. Those profiled teeth, pins and ramps do a remarkable
job of helping the chain climb UP to a LARGER chainring, though backing off on the
pedaling pressure still helps.
If you rarely ride on hilly routes, consider ditching the
huge difference in chainrings and improving your shifting in all conditions. 14
or 16 tooth differences make for a wide range but chainrings with less
difference shift better and let you keep a more constant cadence without so
much shifting. Pros at flat races like Paris-Roubaix often set up their bikes
with 44-54 chainring combos….they know that 10 tooth difference makes for
better shifting.
Need a low ratio but still like the idea of smaller
differences between chainrings? Consider a triple chainring setup. While some
makers supply triples with a 39-53 pairing and a 28 or 30 tooth inner ring
(which really doesn’t improve things much) others offer cranksets with closer to 10
tooth differences, like 30-40-50 or 32-42-52. They know this makes for a nice
progression and good shifting.
“Shift early. Shift often.” All systems shift UP (to a
larger ratio for more speed) better than they shift down, especially up front.
Finding out you’re in a lower gear than you need is MUCH better than vice-versa
and your drivetrain (and mechanic) will thank you…..and you might never drop
your chain again!
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