justcrankn

I'm having trouble shifting to the granny ring on our new (to us) bike with DuraAce FD. When the inner limit is set to Shimano specs it won't shift to granny. Loosen the inner stop and it will shift, but it's prone to dropping the chain. I've experimented with FD height and rotation to no avail.

Will Shimano chainrings make any difference?
Should I just set the inner limit loose and install a jump stop?

2007 CoMotion Supremo, FSA SLK crankset with FSA 30,39,53 rings, DuraAce 7803 FD. I had my LBS adjust it and he set it at a compromise between shifting ok and dropping the chain. This is my first experience with 10 speed and with a CoMotion.

Al Bundy

Disclaimer about your specific bike, but I use a jump stop and have been very happy with its performance.

I dont mind if the shifting up to the big ring is occasionally fiddly, but when I want the inner ring, then I want it NOW. Hence I have set the FD to really throw the chain inwards in a sort of suicide attempt to drive the chain into the frame and in this way I never have issues when I need to downshift. It really helps knowing that its there when you need it.
cheers
mike

professorbob

You'll hear a lot of noise from people about the FSA crank. Not sure whether it's warranted or not, but try setting the inner limit loose and putting in the jump stop. Sounds like a good solution.

tandem rider

I have both Ultegra and FSA cranks and I prefer the Ultegra but they have not been available for a few years. The tandem mechanic at my LBS says that the spacing between Shimano rings is not correct for FSA and shifting will not improve. Good advice on the two previous posts about a jump stop is good advice.

Bill G

I have 10spd STI Ultegra on our Co-Motion with a FSA Gossamer Triple Crank in 52-39 and a 28 for the grany gear. I also use the Jump Stop for plain old good measure and our Co-Motion shifts perfect and smooth. Most of the time about 90% of the time it's just getting things adjusted to spec. The front Deraileur should be lined up straight with the outer rings teeth running inline with the outer sides inner edge of the Deraileur, there should be apox 2mm to 2.5mm gap between the top of the chainrings teeth and the outside leading edge of the Deraileur when lifted even with or above the outside chain ring. After this the chain should be on the little ring in the front and the big cog in the back and the set screw should be set on the front Deraileur to maintain around 2mm clearence between the chain and the Deraileur spinning the crank checking the clearance. The next step after this is the cable should be pulled up in place and tightened down with no slack in it with all inline cable adjusters turned all the way in so there will be future adjustment for cable strech. Now the low side is set. Shift to the big ring up front now and the little cog in the back and set the high set screw to maintain about 2mm clearance between the chain and the derailer spinning the cranks around checking clearance. (Note) shift back to the middle ring to make the set screw adjustment then back to the big ring this way your not grinding the set screw into the stop with pressure on it. If all is set right and nothing is worn out it should shift with no problems.

Sorry I do not mean to sound like a know it all but I have worked on and repaired a lot of tandems over the years and when there not adjusted right they can drive you crazy.

Also get a Jump Stop and set it to spec they are worth there weight in gold.

Best of Luck,
Bill G

dvs cycles

Use a Jump-Stop and make sure that when the cable is in the default(granny) position that there is hardly any tension on it. Just enough to take up the slack.

dfcas

I assume this is an STI shifter? Since STI front shifting issues never end, consider using a bar end shifter. Or a Campy Ergolever

Bill G

STI shifts just fine if adjusted correctly, all of my bikes shift great and smooth as glass including the Tandem, all have STI shifters. With that being said Bar Cons are full proof and shift great..

Take Care,
Bill G

justcrankn

I don't see how the shifter is behind this problem. It seems to be more of a problem between the FD and crankset/chainrings.

mkane77g

I have the exact same bike as you, 07' Supremo. I try and have the chain about 3 cogs down so the chain line, when shifted is perfect, this may help keep the chain on the sprocket. I try and never maked this a last moment shift, it's no good when it misses. How do you like the bike? I have had issues @ times. Mabey a little more cable tension so it doesn't slam. Keep fine tuning, you'll get it right.

uspspro

more aggressive limit setting + jump stop device = problem solved.

tredlodz

+1 on the jump stop. Tandem shifting to granny is always a little tricky
1) Plan ahead - try to do it before the steepest point
2) Often it works better if you're not already in the largest sprocket
3) Communicate: This is the one change I'll yell out for
4) Stoker needs to back off the power, not just the Captain for the smoothest shifts (a key reason for 1))

I'd say this worked 90% for us - the Jump stop is good insurance

Carbonfiberboy 

Another Jump Stopper. As above, plus we accelerate in the granny, then call out the shift from granny to middle ring so we both back off. I wait to shift to the middle ring until we're in the 4th cog in back. Then I don't have to set the cable tension up to get that shift. We have a 26T in front, FSA cranksets. Works great, except that I can't use the top two cogs in back with the middle ring. I'll replace the chainrings with Ultegra when we wear out the FSA. Friends have done that, said it works fine. I set the gears just like Bill G recommends.

joe@vwvortex

Why can't you use the top two cogs with the middle ring? Because of the Jump Stop? I'm in the process of going to a 26/39/53 in front with an 11-29 in the rear (Campy 10) and was considering getting the Jump Stop. However - if it makes me give up the top two cogs in the middle ring - i'll look for other alternatives.

jnbrown

Because with such a big differential between the 26/39 rings the chain will rub against the inside of the 39 when using the 26 with the smaller (rightmost cogs) in the back. I assume "top" means smaller or else I misunderstood.

joe@vwvortex

Ok - definitely misunderstood. When you said top - I figured you meant to the top of the cluster - not gear range. Thought it was odd. I have the same issue with my compact crank in the small ring - rubs the outer when in the last two gears.

Carbonfiberboy 

Yes, top means smaller to me. I can't ride those two cogs in the middle ring because the chain catches on that pin that sticks out on the inside of my FSA big ring. I don't have any trouble with the chain rubbing on the inside of the 39, mostly because I never shift past the 5th cog while in the granny. The smaller the chainring, the greater the chain tension and thus chain wear, a bigger deal on a tandem. So I ride in the largest chainring that will do the job without cross-chaining.

Bill G

Big Time cross chain issue,(This goes for any set up or configeration of gears with a tripple chain ring set up) When useing the small ring in the front one should only use the top 4 to 5, 6 cogs in the rear and when on the big ring up front should only use the bottom 4 to 5, 6 up in the rear anything more than this on any set up is called exstreme cross chaining and is bad bad for the drive train. The exception is the middle ring up front you can use all the cogs in the back with no real issues with cross chaining the drive train.

By not keeping the chain lines within reason one can pre maturely wear out the drive train and yes have performance and shifting issues. Take a look at any manufacture tuneing and shifting procedures or data and you will see that they talk about cross chaining in detail with pics of the proper chain line in refference to the gears and cogs .

Ride Safe,
Bill G

justcrankn

When in 12-39 (smallest cog-middle ring) the chain keeps jumping the pins on the big ring (53). The LBS said it is normal. Could this be related to my original shifting problem?

justcrankn

We've only had the bike out for one ride before I got hurt elsewhere. Stoker says it felt different than our Trek T2000, I couldn't tell the difference-they're both good. Interesting how this "racing bike" is 3.5 lbs heavier than our Trek, but that includes a disc, WoundUp fork and couplers.

Bill G

Sometimes what your talking about can happen in the configuration your talking about. If the Bottom bracket housing is welded off just a mm or the chain stay is off just a little not enough to notice or be out of spec or a spacer was left out of the bottom bracket install if required common with FSA cranks moving the rings and crank in a mm or so inward more than they need to be or sometimes out a mm or so. All this kind of stuff mentioned can contribute to this. Some bikes just don't like the small cog in the back with any other ring than the big one in the front. Also some cranks just have larger chain ramp pins that cause this issue in the configeration your talking about. 9 & 10spd stuff has very tight tolorences 10 being real finicky sometimes.

Ride Safe,
Bill G

Carbonfiberboy 

Not related. It's just how FSAs are. Same on my bike. Nothing wrong with your setup. You can see exactly what it's doing if you put it on the stand. I now use the big ring for all the rear cogs except the inner 2. That works fine, maybe better. More teeth are going to wear more slowly than few teeth. Plus you want to ride with your chain up on the carrier as much as possible. The smallest cogs don't have a carrier and tend to bite into the hub on a tandem.

If you work out the gear-inches for all your gear combinations on a spreadsheet, you'll see where the middle ring can fill in gaps that the big ring leaves.

fietsbob

You have the right side drive crankset on the Captain's Crankset ? (long chain)Long
or the stoker's crankset? ... much shorter.

Classic Tandems in the 50's did run the chain all the way back , from the front crankset.

that long a chain and chainline matters much less.

CaptainLane

Another thing to consider is the age of your chain. Chains tend to get more flexible as they get older, therefore more push from the front derailer is required. The jump stop sounds like a good idea.

merlinextraligh

Really not surprising. The Trek is aluminum, and the Supremo steel. My guess is that the Trek frame probably weighs the same or less than an uncoupled Supremo.

The components are farily similar. Add the weight of couplers, disc brakes, and a disc compatible front fork, and it's going to weigh more.