Tandem Cycling - DaVinci front derailer issues
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01-01-10, 09:12 PM
My wife and I just bought a DaVinci Grand Venture about 2 months ago. We ride it about once a week. I am an avid recreational cyclist, and have been riding road bikes for over 20 years. The problem I am having is shifting the front derailer. It seems like sometimes it needs 2 clicks to go from the big chainring to the middle one, and then one click to go back up to the big chainring. I'm having the most trouble getting it from the smallest chainring to the middle chainring. Sometimes it won't get there even with 2 clicks, and then with a 3rd click it jumps all the way up to the biggest chainring.
I've fooled around with the shifting with the bike up on a work stand. I can see the front derailer uses more than 3 clicks to travel between the various chainrings, but is there some system for shifting between the 3 chainrings? So far it seems pretty random, and I end up doing a lot of over shifting and then adjustment clicks.
Any advice would be greatly appreciated.
01-01-10, 09:44 PM
What kind of chain rings? Does the middle chain ring have ramps and pins?
Maybe the derailleur cable is not tight enough. If it is too loose the derailleur won't move far enough.
The cable should be tight when the shifters are in the lowest gear.
01-01-10, 10:03 PM
This is a daVinci with Shimano STI shifters and three chainrings I assume. We don't have the same setup on our daVinci, but we have found that the FD requires careful adjustment. We have four chainrings, 1-4, with 1 being the smallest. The 2-3, 3-2 shift can be the most troublesome especially if I've let the cadence drop and am trying to shift from 3 to 2. Although the FD is definitely set up "correctly" it's almost as though I'd like to offset the FD movement by 1/2 click so I don't snag the larger chainring with that last click. While I wouldn't trade the Campy Ergo shifters in general it's almost as though a bar end friction shifter would be superior in this one instance. RD, of course, shifts like a dream.
One additional observation: Changed to an 11-34 cassette and needed a new chain. Bought two Shimano cn-7701 and if I didn't know better I would swear this chain shifted better than the SRAM I had been running on my 13-30. Time will tell. YMMV
01-02-10, 06:08 AM
My wife and I just bought a DaVinci Grand Venture about 2 months ago. The problem I am having is shifting the front derailer. Any advice would be greatly appreciated.
Questions: Do you mean a daVinci Grand Junction? Did you buy it new?
Suggestion: If you haven't done so and assuming you bought the tandem new, let your dealer and/or daVinci know about your shifting concerns and see what they have to offer. The original owner of a daVinci (or just about any other reputable brand of tandem), post-sale support is part of what you pay for. Moreover, they may have already encountered the same issue with other owners and may have a ready solution.
My assessment: It sounds like a basic cable or cable housing problem, i.e., there's a kink in the cable, the cable housing isn't seated correctly, a cable-end wasn't fitted with a ferrule, or there's simply too much cable housing. If it were me, I'd probably pull the cable and housing off the bike, inspect it and then do a reinstallation by the book, making sure there was no excess cable housing, that the ends were all cut cleanly, and ferrules were installed followed by a good pre-stretch of the cable once it was re-installed. After that, fine tune the movement using the barrel adjusters at the cable stop (assuming they still fit those to Shimano's Tiagra level components).
01-02-10, 01:41 PM
Absolutely sounds like a cable issue; all the symptoms you describe would lead me to look there first. Listen to the Geek; he speaks the truth.
Second, depending on where you bought it, it might do no good to return to the bike shop. My experience is that with extremely few exceptions, bike shops just don't know beans about the da Vinci ICS system and how it works. There are a few dealers that do, definitely, but not many. Please call Todd at da Vinci. He's the greatest at customer support for his products...and he owns the company to boot. He will treat you right.
Call Todd directly. He will take care of you.
01-02-10, 07:28 PM
I agree with the advice to call Todd. I've often wondered if the Shimano 3 ring setup should provide 1 click shifting. Certainly the 4 ring Campy setup that we have does not and it is the slightly annoying tradeof for having the fantastic gear range that the 4 ring system provides. It typically takes 3 to 4 clicks to downshift our setup and it is easy to overshoot. Upshifting is better but I sometimes jump two rings.
01-03-10, 03:00 AM
One more thing to check is that the front derailleur cage is lined up completely parallel with the chainrings, and is not pointing inwards or outwards. This would probably be noticeable because it would also cause increased chain rub in certain gear combinations, but it can cause shifting problems even if it is not extreme enough to cause much more chain-rub, so I would take a look to make sure it hasn't moved a little.
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