I'm not what you would call a bicycle mechanic, but I do wrench on my own bikes enough to keep them going. I even changed the cables on my road bike last year - that was a pretty big job, but I was successful.


The reason for this intro is my Cannondale tandem (with disc brakes) has a 3X9 setup which I've never really liked. The shifters annoy me, the 3X gearing on the front never seems to be lined up right and the RD doesn't take up all the chain slack. And now the middle chain ring has a bent tooth, which causes skipping. I would like to fix the problem soon since it is bad enough to make me not want to ride the bike. I went to one of the local bike shops and without seeing the bike he estimated changing to a 2X9 or 2X10 setup with "bread and butter components" would run in the $1700 neighborhood .


I've been reading posts here about switching to full right hand drive, and that sounds cool, but the LBS dude said "no, you can't do that"... Made me realize that wasn't the right shop to go to.


I've been looking at CL for drive line parts to save money but have no idea if they will even work on a tandem, much less be an improvement over what I have.


So I guess I'm looking for some advice here. I'm more than happy to do the work on my bike, but I don't want to have to do it twice. Or, if tandems are specialized enough, should I be looking for a local mechanic who is well versed in tandems? I'm not sure how to find that since these bikes are so few and far between.

What age is the frame? 9-spd in the back could mean you can't fit a 10, depends on the dropout spacing. Your biggest concern will be needing a pretty large ring on the back to maintain a usable gear range, but that is not insurmountable. A 2X10 e-geared drivetrain with all the bells and whistles might get you into the $1700 range, but you have a lot of options and if you do a quick search on here you'll see quite a few threads that discuss 2X solutions that have worked for people.

I will recommend that if you are considering doing the work yourself, that you should first get your existing drivetrain dialed in, just to give you the experience and confidence to do the work. Then you can change one thing at at time.

I second this.

3x9 is a proven system that provides the most range for nearly any terrain. Most issues come from them being improperly set up. I have learned to get even very low end systems to work way better, simply by watching videos at Park Tool, youtube, etc. Which tells me that some shops or builders don't take the time to dial this stuff in. Moving to 2x adds other variables and challenges while reducing your range. And doesn't eliminate the front derailleur concern anyway. If you take the time to learn how to dial in your existing stuff you will have a great appreciation and reference point for planning future changes. Or may even decide to keep it as it is.

However if you still have specific questions maybe you can share with us:

1. What make/model are your derailleurs and how old are they?
2. What make/model shifters are you running?
2. When was the chain last replaced? And by whom?

A.) Bent tooth/ chain skipping: Rear wheel needs to be off the ground/ preferably in a repair stand. you need to put a small stick against the mid chainring teeth to find that bent tooth. You need to mark the tooth. Maybe masking tape on the chainring below the tooth line. Next you need to find a way to tap on the tooth till its the same as the others; test ride it.
B.) Chain not taking up all the slack: See how the length looks like in the big ring/ big cog. Could the chain be any shorter? Is so shorten it. That should help with taking up slack, unless the rear derailleur is a short cage or some other unforseen factor.
C) Front derailleur adjustment: Shift the rear derailleur up the large cog. Shift the chain from the large ring down to the mid ring. Make sure that the inner plate of the front derailleur is almost being grazed by the chain. If it is too far away , then shifting will suffer, so it will need adjusting ( via barrel adjuster) until almost grazing.

All very good advice. Over the years I have always found triples to be finicky, but when dialed in, just fine. I’ll add the following;

-if the middle chainring is bent, chances are it’s worn. It might be a good idea to replace it with new. Go with a ring from one of the big guys, I.e. Sramano. Ditto if you are having issues climbing into the big ring.

-chain - if you are using a 10 speed chain, consider a 9 speed. The outer width of the links/pins is a little bit wider and may have an easier time engaging with the pins and ramps in the chainrings.

-Derailleur capacity. If the derailleur is not taking up max slack, it could be that the chain is too long as mentioned above, or the derailleur capacity is not large enough for your drive train. Capacity is easily calculated based on max and min tooth counts of the crank and cassette. You will need to know the capacity of your derailleur. Google all of this, find your number 2 pencil, and it should be apparent where the issue lies. If you can’t find the derailleur specs online, reach out to the forums, or try shortening the chain (this is best done with an old chain, or do it with the existing chain when you are installing a new one).

If you have a capacity issue, there are 3 options

1- change the derailleur
2- change your gearing range
3- live with it.

If you opt to replace the derailleur, also pay attention to the derailleurs max cog size.

Changing the gearing range will result in loosing high end, low end, or both ends of your gearing range. This is a personal call and a great use for a simple spreadsheet analysis.

If you decide to live with it, you could shorten the chain so it won’t go into the big-big, but I would recommend highly against that. You don’t want to shift into a condition where your drive train locks up while you and your stoker are pedaling. The risk of crashing or damaging the drive train (or both) is great.

Good luck.

As for gear ranges: if you think of making any changes, this gear calculator is really easy to use: Bicycle Gear Calculator You'll see the differences there pretty quickly.

If you are using stock components and didn't change crankset/chainrings, cassette size or chain before, I would assume that the rear derailleur is designed to take up the slack and you shouldn't have to change that.
Take some pictures of all gear components and the issues (configuration with chain slack, bent chainring) and post it here, it'll make commenting easier.

Trying to keep to the lowest budget, I’d just replace the middle chainring and put in some elbow grease. Clean and lube the cables, cable guides, derailleurs, and chain. Then take the time to fully tune the shifting for both derailleurs.

Switching to a double may make it easier to tune the front derailleur. The cheapest approach is removing a chainring, then tuning the shifting. You’d probably have best results with two new matching double chainrings installed in the inner and middle positions. Try 52/36, 50/34, 48/32, or 46/30 for a combo - depending on your needs. You don’t need to replace the shifter or front derailleur.

As for right side drive, that’s not going to make your shifting any better. Poorly setup right side drive will result in lots of frustration on the road when the drive chain gets tangled with the sync chain. There aren’t any stock cranksets that would be a major upgrade over whatever tandem crankset you have AND give you the correct chainline for the rear hub.
I highly recommend taking some pictures to share with the forum, and sharing more specs from your setup.

Thank you all for the great advice. The shifters are Ultegra, which I think are good enough for me.
I tried to straighten out the bent tooth, and managed to get the chain to stay on the chain ring, but it was still bent. I could see the chain move maybe .05 in that spot as I rotated the crank. I found a local bike shop that had a middle chain ring in stock so I just replaced it.
My wife and I were going to go for a ride today, but plans changed. Hopefully we can get it out soon.

Sounds like you got those Folsom Shifting Blues! Sorry, couldn't resist :-)

$1700 is way high for simply changing to a 2x setup. With this being a hugely popular setup in the MTB world, there are plenty of good components at reasonable prices out there. If you have a 9-speed cassette hub, which it sounds like you do, you can fit 9-10-11 speed MTB cassettes on there to upgrade. Shimano SLX/XT level (M7000/M8000) 11-speed components are pretty good values and have cassettes up to 46 teeth to get you some decent low gears with a 2x front setup (I have this on my Santa Cruz MTB). However, as far as I know the 11 speed MTB stuff is not compatible with road shifters. You didn't say whether you have an MTB or road tandem. If an MTB/flat bar tandem, I'd seriously be looking at the 11 speed SLX and XT stuff (basically the same, but the XT is a little bit lighter and more expensive). If you need road shifters (drop bars), then your options are more limited because the road and MTB components are generally not compatible, unfortunately.

All that said, there is no reason why your 3x9 shouldn't be working well, given some competent attention from a good mechanic. Sounds like it just needs to be dialed in a bit. Correct chain length, a RD with a cage suitable for the amount of chain you need to wrap, a FD set up correctly, etc. Assuming all the components are in good shape, find a local shop that's good and spend $100 on a good drivetrain tune up.

Totally simple: change out at least the two outer rings. First read a couple other 9 sp. triple threads which are on here right now.

I have 2 bikes with 9 sp. triples, including our tandem, and one 10 sp. triple. Shifting problems with any of them have usually been cable issues. That said, I have worn out an Ultegra left brifter on one bike and the right Ultegra brifter on another. I've replaced the badly worn left brifter on our tandem with a 10 sp. triple brifter. Works perfectly with my Ultegra 9 sp. FD, though the shifting pattern is a little different from the 9 sp. brifter.

If you don't have Ultegra brifters, you might consider buying a set of 10 sp. Ultegra triples. I bought mine from bike24. I'm only using the left now, but I can see a day when big 9 sp. cassettes will become hard to find. You should probably have the bike shop replace that brifter if you opt for that. And have them recable it with Jagwire cables and housings - and adjust the FD.

Philly, I do have drop bars, it seems that with the popularity of gravel bikes brifters for 2X10 should be way easier to get, but what do I know.


I agree with what a lot of folks have said here, my 3X9 setup should be able to work well. I think the cables may be something for me to consider replacing though - I know the last time I screwed around with the RD I replaced the cable housing since it was pretty gummed up.


For now, I've got a new middle chain ring - waiting for a chance to get the tandem out. My stoker seems to be waiting for the weather to warm up. California. Makes you soft.