Barrettscv 

I'm considering installing a double crankset and derailleur on a bike with Shimano 105 5603 STI brifters. The bike currently has a 105 triple crankset.

Will the triple 5603 STI brifters play well with a double front derailleur?

rccardr 

Yes, it should work fine if you set it up to use the small and middle ring settings, locking out the big ring with the limiting screw.

HillRider

That's not what you want to do. Set the shifter up to use the middle and big chainring position and lockout the granny ring position with the low limit screw. That way if you forget and overshift to the non-existent granny position the only consequence is a slack cable.

If you lockout the big ring position, trying to overshift can break the shifter internals.

Kontact

Is this something you got from a manual?


Every time you shift into the big ring you are essentially overshifting against the shifter internals and the H stop. What's different when you do it from the middle ring position of the shifter?

Most shifters sold as 2 or 3 have you start in the lowest gear. Having the shift cable hanging slack from an accidental downshift is going to create problems with the housing getting stuck.

Mr IGH

Yup, that's how I've done it on several bikes. This is the right way to do it if you don't want to break your shifter. LOL on the slack cable being a danger, gotta love the internet OSHA inspectors

Kontact

You're comparing the "danger" of breaking a shifter by using it the way it was designed vs. the "danger" of getting the housing stuck half out of stop.


Seems like both are at about the same level of concern.

shelbyfv

I have a couple of bikes that use 6603 shifters with a double crank and FD, works well. IIRC, Shimano advised using the middle and large settings but that didn't work well for me and I ended up using small and middle. It would take a really good shove to force the shifter into the large ring position against the limit screw. Have to be pretty ham fisted, IMO. May as well try it the "correct" way but don't hesitate to use small and middle if you need to.

rccardr 

<<shrugs shoulders>>
I've done it that way a bunch (small and inner ring settings) and never had a problem. If you're going to overshift while already in the big ring, well, you're going to do something you're not supposed to do anyway... breakage is breakage regardless.

But no reason you can't set it up with big/middle settings, should work fine, same pull done either way.

Steve B.

Obviously the OP hasn’t gotten the news that triples AND doubles are out, 1X is in.

So scrap the whole concept, lockout the small AND big ring, and get an 11-40 something cassette.

Apparantly front shifting currenly sucks and is getting worse by the minute.

Barrettscv 

Poor attempt at humor.

HillRider

As a matter of fact, yes. A manual from some incompetent source named Shimano.

Have you ever really tried this? The amount of slack cable that occurs from shifting from the middle to a missing granny position is very small and is never going to create a hazard.

70sSanO

I've heard that is the correct way, but I've always blocked out the large ring on a mountain bike because of the terrain situation and needing to make a shift and then have nothing happen would be more of an issue than the over shift breakage issue.

In theory I can see your point on a road bike. In practice when someone is pushing a big gear, wanting to shift up from a 50t chainring might be a rare moment in time or maybe a rare individual.

I also wonder if this is more prevalent for early STI shifters that tended to have their share of issues.

John

Kontact

The manual says it will break the shifter?