Chainline and front derailleur
My wife and I have owned a KHS Cross tandem for about 1 1/2 years. I have never been terribly impressed with the front derailleur and the chainline. The front derailleur must have a fairly weak spring because it will only downshift if the pedals are nearly completely unloaded. Even then it may take several revolutions before it happens. The chainline is also an issue. The bike is 3x8 or 24 speed as equipped, but only 1/2 of them are usable. The chain will actually rub on the next bigger chainring and the shifters do not have any 'feathering' clicks.
Does anyone else have some or all of these problems, and if so what fixes have you come up with?
There is a very good chance that poor chainline (chainrings too close to the frame) is also the primary cause of your shifting woes. It could be that the bike was built with the wrong BB cartridge. Is it practical to take the bike back to the shop that sold it? If not, a well-equipped mechanic can install spacers under the RH BB cup to improve chainline. Worst case, you will need a new BB to give good chainline and centered pedal "tread." But I'd try the spacers first.
The "feathering" clicks you are referring to are known as trim. The issue with the derailers may be the shift cable adjustment or the limit screws as well. You should not be using combinations such as large/large or small/small even though they exist.
Yes, but that only takes out perhaps 4 of the 24 combinations, and the OP said only half were usable. Without any trim, I could see that happening.
Originally Posted by jccaclimber
What he said.
Originally Posted by bikeriderdave
I thought I would post an update regarding our problem and the solutions so far. I took the bike back to the LBS where I bought it. They felt that the chainline was good so they did not mess with it. The front deraileur did not need to be replaced. The derailleur probably twisted slightly, this is what had caused the major change on the fronting shifting performance from one ride to the next. They also adjusted the cable tension and cleaned and lubed the cable. The poor shifting performance from the big ring down to the middle ring seemed to be a combination of calbe tension and too much friction in the cable.
We took the bike out for a 40 miler on Saturday with hils and did not have any further problems with the front derailleur. Because the front derailleur does not have trim, I still am not very happy with the total number of usable gears. This leads me to my next request:
I am now thinking of changing the shifters from the flat bar 8 speed currently on the bike to some drop bar brifters in either a 9 speed or 10 speed configuration. The goal of the equipment change would be to give me better derailleur trim as well as improve the large jumps in gearing I currently have with the 8 speed. I would like feedback from people regarding using 9 speed versus 10 speed. and what models have good trim for the front.
Brifters: We're using Campagnolo Ergo shifters. They give me trim on the front: (seven positions total, generally about right on the triple). Apparently it is now possible to select among 8, 9, or 10 speed in the rear, using a kit. So a) you can make the change without going to 9 or 10 speed; and b) you aren't locked into one of 9 or 10 speed.
Originally Posted by ljonesjo
Regarding 9 vs. 10 speed, a 10 speed chain is thinner than a 9 speed. So you're going to be going through chains faster. And a tandem already puts more stress on the drive chain, so you're already going through chains faster than on a single. For my money, a 10 speed is not worth it.
What it gives you, if you're willing to put up with the faster wear on the chain, is slightly closer gear spacing. Tandems do seem to want more precise choice of gear - as in we're shifting way more often than on a single. But the difference between 9 and 10 isn't huge as far as that goes.
I upgraded from 8spd to 10spd and went with Ultegra shifters and an XTR RD. The Ultegra shifters have a single click of inward trim on the big ring and fine clicks of outward trim on all three positions.
I am still using the 8spd 105 triple FD and Shimano square taper crankset, but my FD shifting is still improved over the same FD with the 8spd shifters.
The rear shifting is perfect. I am using teflon coated cables for both derailleurs now.
Check your hub to make sure it can take an 11 tooth lockring before buying an 11-xx cassette, not all 8spd hubs will take an 11 because the lock ring will bottom out before the cogs are tight. All should be able to take a 12.
I'm using a Wipperman chain with the connex link. I don't ever put chains together with pins on any of my bikes. The chain tool is only used to shorten new chains to the correct length.
Also, if you have V brakes, you will need to get a "travel agent" to compensate for the difference in brake lever pull ratios.
Last edited by andr0id; 04-06-09 at 02:29 PM.
Gear Combo Guru
Shimano brifters don't give you much control over the front derailluer. My solution is to use an Ultegra brifter with XT rear derailleur, and then a bar-end shifter with the Ultegra front derailleur. The bar end gives a full range of adjustability and control. Unfortunately, if you don't have extra parts lying around like I did then this may mean buying two sets of shifters, which becomes expensive. Alternatively, single brifters are occasionally sold on ebay.
EDIT: Also, if you use a bar end for front shifting, then you can use a V-brake compatible lever on the left side, meaning that you won't need a travel agent for the brake that lever is controlling (normally the front brake). Cane Creek and Tektro make a more comfortable and modern drop-bar V-brake lever than Dia Compe's more classic lever.