Winter Cycling - Tiagra RD freezes up below -10C

I'm riding a hybrid with Tiagra on the rear. Anything below approximately -10C or so and I know that the rear deraillreur won't work. That's why I try to leave it in a middle gear when I finish a ride. The rear thumb/finger shifter moves but has no 'action' to speak of. The FD hardly ever fails to operate although at -20C it takes a few good presses to effect a chainring switch. If I bring the bike in the house for a couple of hours before riding, both FD and RD work well when I head out.

Question. Is my problem more likely to be moisture in the line or simply a frozen RD. If the latter, any quick fix solutions?

There was somebody else on this forum that said replacing their cables fixed a similar problem for him.

I notice that my RD gets sticky when it's down below 0 (F). I can always shift down, since the cable is being pulled, but things need to loosen up before I can upshift. I haven't checked to see if it's the cable or the derailleur itself.

sounds like water in the cable housing.
though it wouldn't be a bad idea to overhaul the RD.

sounds like water in the cable housing.
though it wouldn't be a bad idea to overhaul the RD.

+1

Try 'rinsing' the cables (use the straw, and squirt inside the housings, liberally) with WD-40.

Same with the RD.

Then lube the RD, conservatively, with TriFlow, or equivalent.

Might help. Can't hurt.

for the RD, you should keep the WD-40 away from the pulley sprockets if possible.
the rest of the thing is made entirely of springs and pivot joints so flushing them out with WD-40 is ok, though they come packed with some grease to keep the moisture out.

for the RD, you should keep the WD-40 away from the pulley sprockets if possible.

Good clarification/addition, though I was limiting the RD to the parallelogram. Could have made that clear.

Generally, keep degreasers (like WD) away from anything that you wouldn't want degreased ;)

90% of freeze-ups I have dealt with are cables. Start there. To check, with the thing frozen, move the derailuer parallelagram back and forth to verify it still moves freely. Assuming it does, you have verified you have a cable problem.

Squirting WD-40 is a good first attempt. Worst case, pull the cables, lube with oil/grease, and re-attach.

cables


the rd just needs one whack and it'll free up if frozen

90% of freeze-ups I have dealt with are cables. Start there. To check, with the thing frozen, move the derailuer parallelagram back and forth to verify it still moves freely. Assuming it does, you have verified you have a cable problem.

Squirting WD-40 is a good first attempt. Worst case, pull the cables, lube with oil/grease, and re-attach.

Easy on the grease at minus 20. That might be part of the problem. Use a lighter lube than you would in the summer to accommodate thickening.

that's why i bike single speed in the winter. less is more in harsh conditions.

other than that, try thawing it out and giving it a good cleaning, sounds exactly like an like ice problem. my brake cables and brake pads freeze up often but that's a lot simpler than derailleur cables. i just hammer on the levers and it solves it self in a few stops.

also be careful with lube, make sure it doesn't contact any braking surface (rims, rotors) that stuff takes forever to burn off in winter

do you have full cable housing or do you have exposed cables?