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Sounds like the ratcheting mechanism is broken. Maybe a bit of wire got stuck inside somewhere? Some people have luck spraying lube inside to try to flush it out but usually an STI shifter doing that is done.

There's a little cog inside with teeth, and a couple of those teeth likely snapped off. It does ratchet up one at a time though, right?

When this happened to an old STI I had on a classic mtb I got in the habit of ratcheting "up"(really "down" to a larger, lower gear?) two or three times as soon as the mech passed those missing teeth. It worked that way for quite a while and did no harm to the bike.

If you can find a replacement cog, it's easy to swap one in. If you're obsessive and miserly, you could tap holes where the teeth were, and epoxy in new pegs. I do not recommend this option.

Shifter's shot; replace the cog or get a new one.

You have several unrelated issues here. First is that you fraying cable was not caused by the crash. Shimano shifters will cause a cable to fray over time. If you run a 1.2mm cable it will last longer than a 1.1mm cable. It will still eventually happen with a 1.2mm cable.

Second is probaly not crash related also. The fast that it is releasing all of the cable at once is because a ratchet is sticking inside of the shifter. Spray the inside of the shifter with shifter out with PB blaster (and only PB blaster). Work the shifter a bit after the PB is applied. Let it sit overnight. In the morning it probaly will work fine.

The shifter is probably shot, but there's a chance that it's just gummed up and the ratcheting mechanism is sticky. If it's like my broken Ultegra brifter, you can't find small parts for sale, but you can take it apart if you're careful and pay close attention to where everything goes. Take pictures and be prepared to replace it.

ohhh i'm excited to see which one of our lucky contestants gets their solution accepted and also which one is right in the long run

Ah, Jason and I posted at the same time. But yes, what he said about fraying cables. They're difficult to inspect, and of course they only fail when you're on a ride. You should probably replace them on a schedule.

Nah, it's the ratchet cog.

Replacing cables (and housing if necessary) regularly is good practice, but this ain't that.

I'm excited to see who wins too!

And Mark, tell the lucky contestants what we might win! I'm sure the lovely Pseuda is standing by Door One, Tabby by Two and...

?

What? Like "Let's Make a Deal" or "Wheel Of Fortune" where they have Vanna or another glamorous spokesperson (who inexplicably doesn't speak) standing next to the prize, (in this instance, whatever we might win for correctly guessing what's wrong with the OP's shifter). Nothing personal intended, if anything please take it as a compliment? I picked "board names" out of the air to try to be funny. I guess I should have used Stu at "Door Number Two" to gender balance?

I'll slink away and forage fungi now...

There's a goat behind one of those doors, isn't there?

I'm sure our board members love being substituted for objectified women on game shows...

Nobody said the cable was the issue, hence the preface "you have several unrelated issues"

Good grief, Pierce. Can I apologize and explain any more completely then I have already for any perceived slight? Pseuda initiated and hosted an event called "Smorgasbike Try-A-Bike Jamboree Picnic Thingie" so I assumed Pseuda has a sense of huma. Tabby is a public figure and fair game, having appeared on stage at Penalosa's "Let's Make A City Liveable". I could be wrong here, and I am not going to check so help yourself, but as I recall it was "Stu" who wrote he'd wear a skirt at a "skirted" Flock ride. If anyone was grievously offended by my post I'll happily salmon the west end bridge for a week at the evening rush as penance, okay?

Now on to identifying the entries in the contest? "Jason's" post which starts out about several issues seems to ignore the OP had already changed the cable. Only issue is the "skipping" of gears when upshifting the rear derailer.

johnwheffner advances the entry that a piece of wire is stuck inside. (Sounds like cable is the issue, eh?)

Jason says "...a ratchet is sticking inside of the shifter."

Lyle suggests the unit may be shot but that "...there's a chance that it's just gummed up and the ratcheting mechanism is sticky."

I believe the toothed cog inside the shifter now resembles an old school hockey player's smile: absent many teeth.

We'll probably never know how it goes, but on the off chance the OP tears apart the shifter and discovers the issue, Lyle, I think the booby prize (and with that term I refer to the avian booby and no part of any human anatomy), is a two week all inclusive stay on "The Isle of Mann" for the annual "Bike Riding Bear Fair", with the recently returned and rejuvenated edwardm as the gracious host and guide.

Is there a "stupidest crap I've had to read on this forum" contest?

I'm surprised Pierce let Lyle's goat comment slip past. [< sarcasm]

In all seriousness, though, I wasn't grievously offended, partly because I know Fungi a little bit IRL. However, objectification of women is the low-hanging fruit of the humor world. Sometimes I just have to fire a question mark out of my feminazi language assault rifle. Internet message boards usually have a readership beyond the folks who also have the chance to joke around in person from time to time, so lets raise the bar with our online jokes please.

Meanwhile, I *was* enjoying lurking on this thread to learn about a new kind of shifter that I have no experience with. Back to business...

If my foot is not on a pedal, it's probably in my mouth...

I'm sure that I'm not the only one! :p

I have no experience with STIs myself but I've been sufficiently scared by what I've read here and other places. It makes me regret not taking a jewelry class at some point so that I could cast my own small parts and build up a better shifter. It seems there would really be a market for anyone who could rebuild or reenforce an STI shifter. The engineer in me wants to buy one and take it apart just out of curiosity.

Question for you folks, the internet consensus seems to be that your are generally ok with a Tiagra or above STI and that the Sora and below are more prone to failure. Is there any truth in this or are they all pretty much equally prone to failure?

Headloss, I have a broken road brifter you can practice on if you want to, and I'll happily throw you fifty bucks if you can fix it along the way. I don't know how different the MTB shifters' mechs are, but I know that failure of the road brifters is annoyingly disuncommon.

woah i love how out of hand this thread got... its almost like this is the real internet now and not the quaint little conversation space i know and love. sigh.

@Pseudacris

Sometimes I'm too lazy to ram my beliefs down everyone's throat. But I also to make sure my comments are sure-footed

@Headloss, that more or less squares with my experience. Even Tiagra is pretty close to junk.

Baah. These internet flamewars are shear agony.

Whoa, just now saw all the subsequent responses. I'll give the PB a shot. It'd be great if something were just stuck in there.

Without a cable in it, it seems to click back and forth upshifting and downshifting just fine. My theory so far is that the ratcheting mechanism probably still has its teeth (or most of them) but they're too worn down to handle the tension when there's actually a cable threaded into the lever. We'll see...

@Pierce + @Lyle: Ewe two are hilarious. This could get unguly.

Pseuda: No kidding around; ewe are baby sheep. Had to chime in as factual inaccuracies get my goat.

@superletour: Even with no teeth, as long as there is no cable tension, it would still behave as yours is doing. The teeth don't wear so much as shear off. On some models a brass pawl will wear (which would not affect indexing), but they make the cogs from a hardened metal specifically to avoid erosion, which would lead to a slow and steady decline in shifting accuracy.

Open it up (carefully). There are only a few small screws holding it together, and see for yourself?

@headloss: The one cheapo STI I tore apart had a toothed cog cast from some inferior "pot metal", and it lasted barely a season. The LX which went "hockey dental" on the coldest night this past winter was 20 years old. Metal didn't look anything special.

Tore apart a ten year old LX over the last hour to get more information. Thermoplastic housing is shot on this one, but guts are good. Toothed ratchet is cut from heat treated steel, and is unworn. Interestingly, the pawl is some inferior steel sheathed with millimeter of some other steel (it appears). How cool is that?

What gets my goat is that parts are not interchangeable between models, nor even between years of the same model (in general), so to meld two together, one needs the identical model from the same year with a different problem. (Unless, of course, one mills a replacement cog or Makerbots a new housing segment...)

That really gets my goat.

To address your question; cheaper ones have wimpier guts.

I definitely would not take my advice from someone telling you to tear apart a road sti lever. mountain shifters do not equal road sti's.

You are right, mtb sti's are not the same as road sti's. Was comparing quality of guts as I've only worked on one road sti.

Used this guide, which was helpful.

@Lyle, I'd love to take you up on that offer. I'll PM when I know that I'll be in town.

@fungi, if you take any more apart for fun, please photo-document (mtb or road). I'm going to start a folder for brifter/shifter internals ideally with measurements... who knows, Shimano may share internals between some of their shifters or perhaps even their fishing rods.

@lyle There's a goat behind one of those doors, isn't there?

I'm standing behind one of the doors, with my GloRioUs Speedo® swimsuit and a pair of Birkenstock Sandals.

With socks.

@headloss: "...if YOU take any apart for fun or profit, please photo-document (mtb or road)...", we can incorporate it into the database of our humble and modest little project coming together over here on the northside. Share data?

"...Shimano may share internals between some of their shifters or perhaps even their fishing rods." The fishing reel idea is indeed clever. I worked on them for seven years, and have boxes of gears and small parts I sometimes incorporate into my art. Have yet to find one interchangeable with any mtb sti component. But one never knows. Even the tiniest Shimano ultralight reel doesn't have internally ratcheted circles as I've seen in road sti(s). And year after year Shimano would change the dimensions of the parts. This contributed to my decision to switch to the long rod for salt water applications almost two decades ago. Even surf casting I use the fly rod and a very nice simple durable and inexpensive reel. Apparently it's caught on in the meantime? (This is also why I won't use anything but friction bar ends.) KISS.

"And year after year Shimano would change the dimensions of the parts."

That is an interesting point, not that they necessarily change annually, but frequently enough that it might explain the lack of spare parts? As for the fishing reel, I just thought I'd throw that out there. Having never taken one apart, I really have no idea... but you figure there must be some shared design somewhere along the way.

With time, the collected minds over the internet should be able to stumble on a few trade secrets. With any luck, perhaps we'll one day have a reliable STI.