Tandem Cycling - From double to triple with Shimano 6500

Hi

who can help me. I got a tandem with Shimano ST6510 shifters 2 x 9. I want to change this tandem into a 3 x 9. The shifters I can use for 3 x 9 as well but I need a new rearderailleur long cage and front derailleur triple.
The front derailleur should be a FD 6503 triple, the rear a RD6500 but of course those are older models and not for sale anymoe. What's should I use instead, what's compatitble with the old 6500 series?

thanks

I'm pretty sure our shifters are the same (though I could not spot the numbers when I looked this morning), and we use Shimano XTR derailleurs: older FD-M900 on front, more recent/available RD-M971 in rear. No issues, good shifts in combo with the shifters. Depending on anticipated terrain, we switch between 12-27 Dura Ace or 11-34 SRAM PG 990.

I would suggest going with the proper front der. Do some searching and they can be found. Ebay often has them, just ensure you are getting the proper size mounting.

As for the rear, should be that any of the 9 speed Shimano stuff will work. Find a shop or place to buy that sells the long cage in the level you desire. It may be a bit of effort but the stuff is still available new if you look.

PK

Our 9-sp Speedster shipped with Ultegra ST6503s, FD6503, & XTR RD. I'd think that XTR should still be relatively available, and I'd think that any Shimano triple FD should work, though I'd agree with PMK that the FD6503 should be the first pick.

I believe you'll find that in regards to rear der and shifters, you can mix mountain and road. In regards to front der and shifters, you need to match road to road and MTB to MTB.

Also, depending upon the number of teeth on the large chainring, it may be a bit funky how the cage radius and chainring radius play.

PK

Apparently the OP created two threads on the same topic. Here's what I had posted to the other thread, I suggest the other thread be closed:

The 6603 is a 10 speed derailer. This matters because the width of the cage on a front derailer changes to match the width of the chain, which is thinner for 10 speed.

Any 9 speed triple front derailer should work fine. The 6603 might work if you are willing to bend the cage a little to give more clearance at the points where it is needed. An 8 speed will work ok as well if you bend the cage to be tighter where it is needed.

A bigger factor is the number of teeth difference between the largest two chainrings vs the cage design of the front derailer. The 6500 and earlier series are made for a 10-11 tooth difference, in other words 52-42 or 53-42. 6600 and newer derailers are made for a 14 tooth difference, in other words 53-39. If you use a front derailer for a chainring difference it is not designed for, it will still work, but not nearly as well.

Rear derailers, on the other hand, don't care how many speeds you have as long as the cable pull is the same. Most long cage derailers will work just fine, except for a few newer exceptions - I think shimano mountain 10 speed is different, and others can probably contribute more accurate info. But any older xt, xtr, etc. will be fine with any speed shifters.

Thanks guys for all the info. I'll start looking for some derailleurs.
About the other topic.
I started this one but couldn't find it any more after checking a couple hours later so I thought something went wrong and deciesd to try it again..
I'll try to delete the other topic, if I can find it......