noimagination

I recently had to replace the left-hand brake/shift mechanism (Shimano) on our tandem due to corrosion inside the mechanism. The right-hand shifter still works, though I can see corrosion there and the brake lever doesn't return to the release position after braking (I have to move it there with my fingers). So that shifter is likely due for replacement soon as well.

The LBS mechanic said the corrosion was due to rain or perspiration. We don't ride our tandem in the rain, much - I mean, we've been caught in sprinkles a few times, but that's it. And perspiration doesn't seem likely as I keep my hands on the hoods or drops, so I don't see how much perspiration can get inside the shifter body during the brief times I'm braking and the mechanism is exposed. However, I will be more conscientious about wiping down the bike after use.

I think that moisture got into the mechanism during transport. We use a roof rack, and we've driven through rain with the bike on the roof several times over the years. I will get a "bra" to minimize the driving rain hitting the bike, but my question is: is it a good idea to use compressed air to dry out the shifter mechanism after it gets wet, or will that just drive moisture into crevices and make things worse?

Thanks for any advice.

(Note: I'm not interested in debating roof rack vs hitch rack vis carrying bike in the car. Hopefully my thread won't degenerate to that type of debate in this forum, as it likely would in the General forum.)

Andrew R Stewart 

It's very rare to see the internals of a STI lever to get rusty/corroded. I've seen lots of handle bars with aluminum oxide under the bar tape, some people sweat acid and the bar tape might as well be a sponge to keep the salty moisture in contact with the bar. When I lived in Raleigh, NC my sweat was so much it would run down my arms and soak gloves and tape. I would let the tape dry out before bringing the bike inside yet the next day the tape would be wet again with no additional riding. I figured out that the salty tape was absorbing moisture out of the air overnight. Fortunately, my sweat doesn't seem to be super corrosive.

My suggestion is to periodically lube the shifters, maybe once a year (which is what Shimano called for when road STI first came out). Compressed air is not what I would use though. It can drive into the tight spaces any grime and make sure water is also driven inside. Perhaps hanging the bike from the rear wheel after water exposure so any can drain out the front of the lever.

I would also be concerned about water getting into the frame. I've seen significant amounts of water dripping out of bikes when hanging them upside down at work, annoying when that happens on your head I hope you have been servicing the eccentric and posts too. Having them freeze in place is a real pain. Andy

Iride01 

30 year old bike or a 3 year old bike?

noimagination

Bike is about 8 years old. My wife isn't nearly as avid a cyclist as I, so it has < 5,000 mi on it. Which is annoying, shifters should certainly last longer than that. Hell, shifter cables can last that long.
Eccentric is fine, I had to replace the front timing chain ring (ran over a deer's leg - long story) a year ago. Also had to move the eccentric to account for chain wear, so the eccentric is fine. The seat posts are also OK, I lube them periodically.
I have spray lube I use for pivot points (brake/derailleur pivots), I suppose I can spray a little of that in there periodically. Hopefully that and the "bra" should take care of the issue.

Iride01 

Was the cable replaced? I too would think 5 years is too early for it to get corroded, but I wouldn't say there aren't some situations that it may be just a couple years. Or even less.

Though I wonder if some of your issues might be a frayed cable up inside the shifter. STI or shift lever? Though maybe not from your description of the issue. But I'd sure check by pulling six or so inches of the cable out of the shifter But that's going to require you to undo the cable at the pinch bolt and readjust after re-attaching.

Trakhak

Long distances on a roof rack, especially if through rain (although condensation from temp changes would work, too)---sounds like the source of the problem. Corroded shifter innards, lube blown out of headsets, etc.---that's why bike bras were invented.

Simplest work-around: wrap the levers in plastic bags before loading the bike on the roof rack.

FBinNY 

Brake levers are pretty well designed for normal exposure to the elements. The larger parts are anodized or plated for protection, and the internals protected by the thin film of lubricant covering them.

HOWEVER - Moving through rain at 50+ mph on a roof rack, especially if front end is in front, isn't normal and not designed for.

So, rain can be driven into a closed lever and douse or spray the internals well beyond the design limits or what a thin film of oil can protect from. Odds are that you can lube and massage these levers so they come back to normal, except cosmetically. But if you're going to use that roof rack, consider covering each lever with a plastic bag secured with a rubber band or reusable wire tie. Consider doing the same if your saddle is leather or leather covered.