Bicycle Mechanics - Change to double crankset, change shift levers too?
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Hi, I'm almost a newbie here but please bear with me because I need some help. I have a bike with Shimano 105 crankset, 105 shift lever, and Flightdeck computer. I switched to a double crankset (dealer offered me that option to make more of a racer). Now when I shift the double, the computer does not register the downshift unless I shift twice! The dealer says this is because the 105 shift lever is a triple still and I would need the double to make it work without the glitch. I researched a little on the internet and could not find different double versus triple versions of the shift levers. So could he be mistaken? If so, how does one go about setting the shifter to double? Thanks, maybe should have let well enough alone.
07-19-02, 08:10 PM
Ok, from the 2002 Shimano catalog:
The ULTEGRA, 105 and TIAGRA dual control lever and SL-R4400 Rapidfire lever can be used with either the double and triple crankset available with each group.
When setting up the left lever for use with a double crankset, use the lever's middle position for the large chainring, and the low position for the small chainring. The lever offers a trim poisition which allows the derailleur to be adjusted to prevent chain rubbing.
When setting up the left lever for use with a triple crankset, all three lever positions are used. (well, duh, Shimano ;) )
Is your front shifting set up in this fashion? You could tell if it weren't, because the front shifter would have one "vacant" shift (for the missing inner chainring). If you pushed your downshift button several times, you'd have a really slack FD cable due to the vacancy.
Also, Shimano's 2002 catalog shows only one type of 105 levers, the ST-5500-CA. Can you look your levers over and confirm that this is the exact model number (including the -CA suffix) on your levers?
Thanks for the help on researching the shift levers. The bike is currently still at the shop, but I'll talk with the shop owner about looking for the shifter model number. Then I'll ask him to try to fix from the manual. I'm pretty sure it is the one you cited. Actually, the problem may be with the way the Flightdeck computer is set up. The fact that the owner thinks there are different double and triple versions leads me to suspect that he is not very experienced in these matters. Thanks,
07-19-02, 08:57 PM
If it is set up with a vacant shift for the inner ring, fixing it will be pretty simple... loosen the cable-clamp bolt, pull the wire taut with a pair of pliers, and tighten the bolt down again, and perhaps do a little fine-tuning of the indexing if needed.
I'm hoping to get my road frame built before the season's over, and put on some Flight-Deck-compatible levers too... Flight Deck looks useful, and I'd like to have that "virtual cadence" feature too. Besides reporting cadence, it would be useful to know what RPM I'll be turning if I pre-shift before I'm able to start pedalling in earnest. :)
Your report based on the Shimano catalog gave me the idea of looking at the service instructions myself at the Shimano website. Indeed there is the capacity of the shift lever to be either a double or triple as you reported. Then I saw that there is a different front derailleur for double versus triple (FD-5500 versus FD-5503 respectively). Now I think that the triple derailleur was left on despite the change to a double crankset. Do you know if that would cause a problem beyond the effect of the Flightdeck computer? Incidentally, I liked the Flightdeck because of the cadence feature but also so I could see the gear I was in without looking through my legs.
07-19-02, 11:58 PM
If it were me, I'd be ok with the triple-compatible front derailleur. The only way I could see it being detrimental is this: the triple crank's outer two chainrings would be further from the frame by perhaps 5mm, and the derailleur could be built with that in mind. If it shifts well, then that's a moot point and the only downside would be appearance.
I don't think the derailleur itself would cause your FlightDeck problem, since the FlightDeck monitors the position of the shifter's guts, not the derailleur itself.
These are all helpful suggestions. Thank you very much!
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