channelz28

I have an '80s Trek touring bike with a front triple and the front derailer cant reach across all 3 gears. I can adjust it to shift onto the biggest, but then it wont get down to the little ring, or vice versa. If I actually position it perfectly in the middle, it wont reach either of the rings. The limit screws are wide open.

The derailer is a Sachs Huret bottom-pull that I took off another '80s Trek touring bike. I assumed it was stock on the bike, but who knows. It has the look of a double, but I always thought a double could still reach 3 chainrings.

I realized that the big ring I have says 53/39 on it so I assume it's intended for a double setup. It made me wonder if it's a bit thicker and that's why the derailer wont reach? It's the only thing I can think of, though it seems doubtful to me. I don't have a triple chainring around to compare. I basically just want to know before I buy a triple derailer and discover that it wont reach either.

Bill Kapaun

Sounds like the FDER is for a double and simply doesn't have enough reach for a triple.

HillRider

What is the shifter? Perhaps the shifter doesn't have enough range to move the fd all the way across the crank.

sweeks

Pretty sure the chainrings are all the same thickness, provided the chain is for a cassette with the same number of cogs (ie, chainrings for a double with a 10-cog cluster are the same as those for a triple with the same cluster).
Amirite?
Steve

McBTC

The rings are the same... but, the derailleurs are different

maddog34

if you can adjust the der to reach either the inner two, or outer two rings, then the der may have enough reach... HOWEVER, the der. has a different PULL RATIO... ok? the der. is probably for a double ring crank...

get a triple ring der.... make sure to order one with the proper clamp diameter.

channelz28

Shifter is Ultegra STI triple, so that's not a problem. I will just buy a triple derailer. Thanks for the replies!

fietsbob

3 is wider than 2 as a total, but the tooth width of the chainrings individually is unchanged

SkyDog75

The shifter itself isn't the problem, but pairing a Shimano indexed shifter with a non-indexed, non-Shimano derailleur is. Indexed shifters pull a specific amount of cable per click and they need to be paired with derailleurs designed to move a specific lateral distance for that amount of cable pull.

A Shimano road triple derailleur should shift across most triple cranksets OK. There are a few things to be aware of, among them:

Shimano STI triple derailleurs have sculpted cages designed for certain chainring size combinations. If your ring sizes are substantially different, such as a "half step & granny" setup, it might not shift well. And if your small ring is too small, a Shimano road triple derailleur might not be able to reach it.

Shimano STI mountain derailleurs use a different cable pull ratio than Shimano's road derailleurs. If you pick up a derailleur from a mountain group (e.g. Deore, XT, Altus, Acera, Alivio, etc.), it may not work.

The newest Shimano groupsets use an entirely different cable pull than previous generations. If you've got the latest Ultegra shifter model, it may not work if you pair it with an older derailleur.

Rowan

This, but it sounds like the issue for this poster is that if it's 9sp, the triple Ultegra is like hen's teeth; 10sp is getting that way very rapidly for the older Ultegra groups, and there are compatibiiity issues with the very latest triples (105) and older shifters. It's become an effing minefield. Is there even an Ultegra triple available any more?