1990trek2300

I recently replaced the whole worn out drivetrain on my old trek, switching it to a 105 9-speed triple setup. Works great, but I'm thinking about switching to a double chainring.

so, two questions:

can I use my new ultegra triple front derailleur on a double crank? if not, should my old ultegra 600 FD (for 7-speed) work with the new 9-speed setup?

also, can I keep my long cage rear derailleur, or should I go to a short cage?

thanks for any help.

robert

TallRider

Triple front derailler will work fine. Heck, triple rear will work fine. And triple-compatible STI shifter, too. All you really need to switch is the crank, and probably bottom bracket. You could even (if you like the first two gears of your crank just fine) get a shorter bottom bracket spindle and adjust your front derailler's limit screws and run it as a double.
The longer cages on the front and rear derailler designed to work with a triple allow these deraillers to deal with a larger difference in gearing. They in no way limit the deraillers from working fine on a triple.
My guess is that your old Ultegra FD will work fine, although the cable-pull on newer FD's designed to be indexed with STI shifters may change things up.
If you have an old Ultegra RD from the 7-speed era, it'll work perfectly with your new drivetrain - cable pull is the same as modern 9- and 10-speed rear deraillers.

capwater

Search this forum, very in depth discussion. In a nut shell, it all depends on how much cash you want to part with. You can go double as simple as taking off your granny ring and readjusting you limit screws on the triple front derailler. If you go with a double crank you'll need a new bottom bracket or your chain line will suck. Could get away with the FD with adjustment. RD will be OK with a long cage.

zonatandem

Why bother to switch? You never plan to do some bigger hills?
I'd leave on the triple: better to have it and not need it, than to need it and not have it!

Avalanche325

Your chainline will be fine. The reason a triple had a wider BB is to give a little more space for the inner chainring to clear the chainstay. Moving the chainrings in or out a couple mm will have no effect on chainline on a multi speed bike.

You can run a long cage on double or triple. The shifting part (parallelogram) is the same.

Wil Davis

I recently changed my Veloce triple (52/42/30) to a double (53/39) and noticed that the profiles of the cranks were very slightly different - so even if the new cranks are the same length as those you're swapping, you still might need to swap them in pairs so that the pedals are spaced correctly from the centre-line of the frame. In my case the 111mm BB spindle was OK for both double and triple (according to Campy specs.) so I used the old one. I changed the FD for a double, but the triple would have worked also.

- Wil

DogBoy

Triple is not as cool as a double

I swapped lots of components around on my bikes. I had a triple road-bike, a double cross bike and a 34/50 compact double tri-bike.

I took the triple off the road-bike and put it on the cross-bike (my commuter/touring bike), ditched the cyclocross cranks and put a compact crank on the road bike. I swapped the front derailleur, cranks and the bottom bracket. Why? The compact crank was cheaper than a triple crank and now I can get used to the shifting pattern on the rollers with my road-bike and be ready to hit the roads in march on my tri-bike. I swapped the front derailleurs & bottom brackets from the cross bike to the road-bike. Luckily the shell size was the same, and my cross bike already had a long-cage rear derailleur and 105 brifters were already triple compatible.

So anyway, the point of all that is that I have no problems with the long-cage derailleur on my double setup. I should learn to be less wordy.

BloomBikeShop

I just switched from triple to double too. I would never use my little ring, so my smallest gear was a 44-23.

Now I have a 39-23 or 39-21. So with this setup, I can do bigger hills!

DogBoy

You could also just have purchased a 39 middle ring for your triple...

1990trek2300

[QUOTE=DogBoy]Triple is not as cool as a double

well, I hate to admit it, but, yeah, that's the real reason. Also, my 105 triple is black, and I miss having a shiny metal crankset to match my other shiny components and frame.

Also, i find I don't use the triple nearly as much as I expected. Besides, once I admitted to myself that I just liked to mess with things for the sake of messing with them, I achieved a certain peace with endless fiddling and upgrading. At least I'm not out modding my car...

thanks for the advice everyone! I tried a search, BTW, but didn't find any tips about the 600 series compatibility and the tech sheets on the shimano site didn't answer my questions about the rear der.

capwater

Pull the granny ring, it'll give you 90% of the coolness factor of a double. Go one step further and replace the middle (now inner) ring with a 39. Be really adventurous and grind off the ears of the triple crank. Best bet would be to eBay that crank for something like 50 bucks and pick up a double for 70 bucks. I would still advocate a new BB, Nashbar has 5500 (105 level) 68 x 109.5 for 20 bucks. All comes down to how much green you want to part with, mate.