Motolegs

While out riding today went to shift the front chainring from large to small- and it wouldn't. The shift paddle just swung freely with no resistance. Was able to duplicate the phenomenon about three times after that- the majority of the time it was fine. It was cold out today, and it was the first time this happened.. any ideas?

maddog34

ratchet grease got stiff due to the cold? downshifts rely on a ratchet pawl engaging a disc... if the pawl doesn't move, there is no resistance at the lever..... and no downshift!

thin it out with a few drips of penetrent oil.

Andrew R Stewart 

I would go through the usual process of separating the various parts of the system and see how each works. The basic three elements are the der the cable/casing/routing and the lever. Each can get sluggish with cold, freezing water, old thick lube. But the cable is the most varied aspect. It's path, the ease for grit to enter the casings and the degradation of new condition are all common challenges for cables. Andy.

maddog34

Andy's got a point there... when(not IF) the cable begins to break, the fraying can do some rather odd things... and you DON'T want to dig the barrel out of the brifter... trust me on that one!

Kimmo

It's almost certainly not the cable fraying, unless you've already replaced the right one, which is the first to go.

In any case, removing a frayed cable from these shifters is NBD compared to earlier ones; plenty of access - IIRC there's a cover under the hood you can remove.

But here's a thing - if you fold the hood over as if you're doing bar tape, you can reproduce this symptom. So it seems the section on the front of the underside under the hood is open, and intrusion can stop the small lever. First thing I'd do is ensure the hood is properly fitted. Then I'd aim some WD40 at the mechanism that lever actuates.

Since there may be a correlation with cold, thinning the lube could be the go.

Motolegs

Thanks guys, I suspected the cold weather might have played a role. The whole setup has about a hundred miles on it from new. Tried shifting it indoors several times last night and it was fine. I'll give WD-40 a try before the next ride.

Tunnelrat81

I would seriously advise against using WD40 on a new set of shifters. Flushing them that way will break down all the good factory grease that's in there, and may compromise any warranty claims you have in the future. The above suggestion was for a drop or two of penetrating oil....WD40 is a solvent. On a brand new set of shifters, I'd give them a chance to break in at least before freaking out. I know it seems they should be perfect, but flushing with solvent is the wrong answer at this stage of their life.

-Jeremy

Motolegs

That's good food for thought. In fact I'll forget about the WD-40. Hadn't considered giving things time to break in.. at any rate it's not a problem that keeps me from riding the bike, I'll just leave it be for the time being.

Yellowbeard

You're probably just accidentally pushing the main lever a bit when you go for the downshift paddle. Did you wear thicker, less dexterous gloves than usual because of the cold, maybe?

Motolegs

For sure I was pushing just the lever to shift to the small chain ring. In fact it swung about twice as far as it goes when it shifts properly, with no resistance at all.

2manybikes

It's the cold weather, if it shifts when in the house. It happens. If you thin out the grease now so that it works in the cold you may not have enough grease to prevent wear when the summer comes. A years old bike can have the grease thinned as it gets very old, the parts may not have a lot of life left anyway. But with almost new parts, I would not want to thin out the grease. When it happens to me, depending on what bike I am on, and how cold it Is, I may just tap the outside of the brifter a few time to get it to shift. It's OK when you ride alone.
I ride down into the single digits (F) every winter. If you own an old bike with friction shifters it will be a good winter bike. Or a single speed, or a fixed gear bike.

Edit - Also after tapping the brifter, and it still does not shift, move the non working lever back and forth too. A tiny bit of heat is created, and the grease can be pushed out of the way. This is not consistent but, it works. Don't be worried it will be OK when the warm weather comes back!

Motolegs

After answering your post above went straight to the bike and "nicked" the entire shifter while pushing the downshift paddle. What do you know, looks like you nailed it, gloves and all. My embarrassment is total.


Kind of has me wishing for a larger paddle surface, like the SRAM mailbox flags.

2manybikes

You need to ride a typical distance or time In the cold, while watching to not nick the other lever, to be sure that is not the only thing happening. Poor shifting in the cold is very common.

Motolegs

Yes, I'll have to take it out again this weekend which calls for cool and dry conditions. For the brutally cold weather this bike stays home.