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here's the question: Can you use a triple shifter w/ a double chainring?

here's the background: I'm leading a beginner women's ride last night and one lady is having really bad gear problems. Like getting off to shift, or having to shift her front d with her right hand, because she has to push that hard. Says it just came back from the bike shop but they didn't fix it.

I get on the bike. I can't make it have any problems. I hand it back to her and ask her to try it now. She says she still can't do it. I get back on. Sure enough, i can't get it to drop into the small ring. (thumb shift) I try repeatedly and finally push the CRAP out of the little lever and it shifts. But after that it goes back to shifting fine.

I bring it back to her and we discuss. It's the blind leading the blind at this point. I'm trying to figure out what makes it start acting up and why she seems to think it's f-ed up ALL the time. finally she says something about not being able to get in "three". What do you mean, i ask? She points at the little red indicator at the top of her shift lever. Repeats that she can't get shift into "three." I point out that she doesn't have a triple. This does not register at all. I point at her rings and we count "one", "two". We find her friend's bike and count to three.

She seemed VERY skepical of what I was telling her, I think she'd been "shifting to three" for a long time. Says she used to have trouble shifting to "one" (shows me the sift to the big ring) but that the bike shop fixed that.

So... I'm still a little confused over what's happening, but I think maybe when she's trying to jam it somewhere it won't go, she's screwing it up somehow, and that's why the shift problem (as I see it) is intermittent. Anyhow, will this fix itself if she stops looking for three? or do triple shifters just not work w/ double chain rings?

(it was Shimano, but I failed to look at exactly what group)

I love the newbie rides. I'm the most helpless, stereotypical female imaginable when it comes to mechanical crap, but last night my ability to change a flat and count chain rings made me look bad ass. ;-)
 

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Tell her to switch to Campy, it goes to 11. Seriously, a triple shifter can be used a double crankset; I've set it up on many bike. However, its not as smooth or efficient as a double shifter. It sounds to me like she needs to totally ruin what she has and, hopefully, learn how to shift and and what is and is not possible in the land of bike components.

To address her indicator landing on all 3, if the cable tension is set to where 2 = the small ring and the lower limit screw is set properly, the indicator would shift down to 1 withiut an actual shift, and therefore, 3 would = the big ring. When I set up a bike like that, I set 1 = to the small ring and 2 = to the big ring. Setting the upper limit screw will keep the shifter from going to 3, but it also eliminates the "dead" shift that doesn't do anything.
 

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It sounds like someone has been messing with her bike quite a bit already, if it's got a mix of parts like that on it. As Daren wrote, it's doable, but not ideal, by using the limit screws.

Some bar top shifters might not work well with certain road cranks... They might not be well matched... I.e. might not move the derailleur the precise distance to ever shift properly or well.

If' she's putting a whole lot of strain on the system trying to make shifts that don't exist, she's likely "stretching" the cable (actually compressing the housing) and eventually will snap the cable or damage the shifter or both. This will cause it to constantly go out of adjustment. If I were working on it and wanting to use the existing parts, I'd set it up one way or the other (as described by Daren), then put a piece of tape over the indicator window blocking the gear she shouldn't be trying to use!

She might want to try another bike shop. I'm not sure how good the mechanic is that she's using now, considering the way the bike is set up.

Alternatively, she might just be better off springing for a new, matched triple crankset and having it properly set up. It sort of depends... damage might already have been done to the shifter and it might need to be replaced. Again, she should get the advice of a good shop on this.
 

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I run a bike with an Ultegra triple left shifter and standard double cranks. It can be made to work but requires much more careful set-up and gives slightly stiffer shifting. As others have mentioned the key is to use the settings corresponding to the little and middle chain-rings on the triple, and to use the upper limit screw to prevent shifting into the gear setting corresponding to the big ring on a triple. If you do over-shift into that big ring position you will be overly stressing the shifter and the cable. It will be hard to get out of that state, and you will possibly break something in time. Of course once you force it into that state it makes it more likely that you will be able to do it again. One also needs to distinguish between full shifts and trim shifts, and that may well confuse things even more.

It is interesting that Shimano only made a triple shifter for 105 for quite some time (5600 generation), and manufacturers routinely speced this onto bikes with doubles and compacts. This required the careful setup as mentioned above. On top of this the 105 triple shifter had a design weakness that caused many to fail in this mode due to the increased stress of shifting when not perfectly set up. There are many threads on this on this forum and elsewhere. It seems that there was a running modification to that 105 shifter to fix the weakness.

Now it seems that more and more bikes are being speced with compacts, and that triples are getting pushed down to the lowest spec bikes only (and touring/MTB bikes).
 

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ukbloke said:
I run a bike with an Ultegra triple left shifter and standard double cranks.
Some Shimano road bike shifters were designed to work with either double or triple (I think I've got a 9-speed group stashed somewhere that includes one of these).

However the OP didn't know what specific parts are on this particular bike and talks in her post about a gear selection display and small thumb lever that sound to me like this is a bar top shifter of some sort.... which AFAIK would be designed for and matched up with a triple crank. So I'm speculating that some of these might have the same spacing as doubles and might be made to work, while others may not work with a double crank.

Either someone has switched to a double crankset.... Or they've removed the smallest chainring from a triple and are running the bike without it.

Either way, I start to get some concerns about the bike shop that's been servicing and maintaining the bike for her. We're not sure who sold the bike to her, if it was used or new, etc.

Chances are it can be made to work to some degree... But apparently she still doesn't understand that the bike has been modified in some way and keeps trying to shift it into a gear that doesn't exist. It might help to explain that to her again, and/or to cover up the unused speed on the display with a bit of tape to discourage trying to use it (if keeping the double ring set up), or do whatever is necessary to go back to using a triple crank so that all the gears will be usable. I'd still be concerned that some damage might have already been done to the shifter, though, and it might need replacement. At the least, if a lot of stress has been put on it for a while now, I might install a new cable just to be safe.

P.S. I wonder if the OP's friend realizes that you need continue pedalling when shifting, to effect a gear change? Maybe she just stops pedalling and starts pushing buttons expecting something to happen. :rolleyes:
 

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ukbloke said:
I run a bike with an Ultegra triple left shifter and standard double cranks. It can be made to work but requires much more careful set-up and gives slightly stiffer shifting. As others have mentioned the key is to use the settings corresponding to the little and middle chain-rings on the triple, and to use the upper limit screw to prevent shifting into the gear setting corresponding to the big ring on a triple.
This. I have the same set up, but with a compact crankset. It works fine.

It sounds like her shop didn't correctly set up the front derailleur.
 

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Amfoto1 said:
However the OP didn't know what specific parts are on this particular bike and talks in her post about a gear selection display and small thumb lever that sound to me like this is a bar top shifter of some sort
It sounds like a Sora shifter - these have an integrated optical gear display, thumb shifting and the left shifter is both double/triple compatible. All the previous points about setting this up correctly should apply.
 
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