Why Shimano shifters stop working in 25F degree weather?
 

Hi all, we've had cold weather here on the USA's east coast. I've always had some problems upshifting the rear derailleur (going from large cog to smaller cog) and downshifting the front derailleur in colder weather but, yesterday, in 25F degree weather it got so bad that I was trying to shift 5 or 6 times before it would click and shift--sometimes it wouldn't shift at all. Very frustrating. My riding buddies said they have the same problem, although it doesn't seem as severe as mine. Can anyone explain what's going on? I have Shimano 'FlightDeck' Ultegra shifters on a racing bike, 10 speed rear, double crank. As always, thoughtful, well-informed opinions are the most appreciated.

Because it's cold out.
The grease inside gets hard and the pawl can't move to click into place and the cold makes it even worse.
The usual remedy, besides warmer temps, is to thoroughly flush the shifter with WD40 and relube with a lighter lubricant.

As above the lube in the shift mechanism can get stiff in the cold and not let the ratchet move. Another possibility is water in the shift cable housings that froze and won't let the cables move. Either can be cured with cleaning, drying and lighter lube.

^This^ And when was the last time you replaced cables/housing?

All you have to do is pull the brake or pull back the hoods to expose the shifting mechanisms and spray some oil in there.

Most shifting problems are cable related. If your cables are old they could be dirty/corroded/etc or have moisture in them that freezes.

Your shifters might need to cleaned and re-greased. Blasting them with WD-40 is the quick fix.

Finally, the rear derailer pivots should be occasionally oiled.

I was thinking cables too, but the OP said he was pushing the lever multiple times before he got a “click” - sounds to me like the shifter itself wasn’t working, as opposed to multiple shifter clicks but no derailleur movement (as you’d expect with a frozen/jammed cable)

Thanks to everyone who replied. My riding buddy talked with a professional mechanic today who said the same thing as the first reply: the grease or oil becomes gummy when it gets that cold. Fortunately, the weather has turned a bit warmer since yesterday and we may have turned the corner weather-wise here in Wash. DC. But I will definitely have to remember the trick to getting the shifters to work, come next winter.

Again, thanks to everyone who replied--nice to know my shifters aren't getting worn out!

Once the grease gets old and hard enough it won't matter what weather it is and you have to do the flush & lube

What do yiz recommend for the shifter re-lube?

The recommended technique back in the days of 7 and 8-speed STIs was to remove the lever assembly from the bike, remove the hood and soak the entire thing in OMS (odorless mineral spirits) with frequent agitation to wash out the old lube and dirt, let the solvent dry and then flood the shift mechanism with a light lube like Tri-Flow. A less invasive approach is to flood the shift mechanism with WD-40 several times, let it drain and then use light oil.

If I understand your wording correctly, those shifts rely on spring tension at the derailer to pull the cable through the housing and let the derailer move. Clean / proper lube (maybe silicone) or new cables might be what you need.

Sometimes the old grease is so solid, you've got to open them up and chisel it out.
I've benefited from this condition, getting older bikes and brifters cheaper because, "my shifters are broken".

On "upshifts" RD spring tension moves the cable, on "downshifts" the lever moves the cable on a "high normal" RD. Opposite on FD.

Certain Shimano STI road levers are also notorious for frayed inner cables at the shifter. I replace my 6600 cable yearly just for that reason.

I use die-drawn stainless inners and lined housings without lube, so no stiffening in cold weather; at least not my cables.

It seems to me that Shimano uses cheap grease, if that's the case. I've used grease that has lasted way longer than this grease. And, yes, I've busted several cables right at the end, inside the shifter housing--boy, it is a real PITA to extract the cable end when it happens! I once had to pay a mechanic $40 to extract it with a special tool.

Overall, my impression of Shimano has not been favorable. They build the STI shifters in such a way that there are no 'user serviceable parts' inside them; they are basically disposable and cost, I don't know, maybe $300 to replace. It would be nice if they warned customers about the importance of inspecting the shifter cable ends every 2000 miles or so. And it would be nice if they didn't use cheap grease...

I also used to curse Shimano's "cheap grease". But I think the truth is that any small amount of grease will harden in an unsealed environment, exposed to air/water/dirt/etc.

These days I've graduated to indexed Shimano downtube shifters. I actually prefer them to brifters, and my 30 year old ones work great. Someday I'd like to tear one apart and see if there's anything to maintain inside...

Those shifters are 10?15? 20? years old now? I'd say the grease lasted just fine without any maintenance at all.
On the cables, before I just replaced yearly I would notice the downshifting degrading and replace. When installing a new one I also use some light grease on the first inch or so by the head where it wraps around the drum when shifting.

It isn't so much they aren't serviceable as Shimano doesn't make or sell the parts so you can service them, or discontinue producing/selling the complete unit for replacement forcing you to up/downgrade.
When the next generation of 10s (6700) came out I bought a set of new 6600 STI on closeout that I still have NIB for future replacement, but have 10's of thousands of miles on the current ones.

if you want “user servicable”, buy Campagnolo, although I don’t know if serviceability and parts availability applies to the newer components like it does to older ones.
FWIW, although I overhauled my 10sp shifters myself back in ~2004, when they were up for another round in 2020, I farmed the job out (being older, lazier and having a little more disposable income). They came back like new, but the job cost >$300, so unless you’re willing to do the job yourself, it seems like “service vs replace” might be a wash

What sort of expensive grease should they use? It is not cheap grease it is fine grease but after such a long time it can harden up. Grease isn't some magical substance that will last forever in every single condition for so many years most old shifters need to be cleaned out and re-lubed. If you have a better grease proposal I would love to here it. Sure maybe the Krytox aerospace grease (I cannot remember which version but it can get like 1k+ per small tube) might work better but you better believe the price for STIs would shoot up even higher using that sort of grease and honestly it isn't needed. Occasional flushing can bring back old shifters quite nicely and using some light lubricant does wonders.

Busted cables is just a sign you need to probably replace them more often, maybe gentler shifting and of course making sure it is properly seated upon first install. Most mechanics and shops recommend replacement every 1-2 years (ish) and at that point as well you can replace your bar tape and not because it looks bad but so you can take a look underneath that stuff to see the bar and see what all your sweat has done being soaked into that tape. If you tune up your bike at lease once a year a lot of problems don't occur or at least they can present themselves so you can take care of it. A bike doesn't last forever by riding it and not caring for it and maintaining it.

I don't think Shimano really needs to warn about care and maintenance on a bike more than they probably are already doing in their manuals. I mean it is usually in every bike manual and most shops and mechanics will tell you to bring it in more often.

In terms of non-user serviceable parts, that does suck and I can agree there but on the flip side it isn't a simple mechanism and a lot of small tiny springs and stuff that are a pain to get together correctly at home without the little tools and such. However yeah I would rather have parts like older Campy levers.

As above, my experience is that Shimano Hard-Grease-itis is common but only after a few years of use, and esp. if the bike has sat in a garage or some other non-temperature-controlled environment for a few freeze-thaw cycles. I have never seen it happen on a new bike. When I opened this thread I was guessing to myself how old the OP's bike was, and '10 speed Ultegra' means it is at least ~10 years old.

Campagnolo quit selling rebuildable shifters around 2009, right about when they went to 11 spd. At least they still make the replacement parts for the 2008 & earlier shifters, but anything after 10 spd is no longer rebuildable.

That's too bad - I'll likely stick with Campagnolo, but I'm running out of specific reasons to do so :(

Thanks to everyone who replied. Very instructive!

Indeed. Grease is an oil suspended in a filler (the lithium complex or whatever). If that oil has evaporated out, or polymerized into longer molecules making it something more of a tar, you're left with a high solids goop, that isn't very flowing any more. There might(?) still be enough oil in it to prevent dry metal on metal contact, but the aged grease itself becomes an impediment to movement.