Since the Double has a trim function is there really a difference? Shimano makes two different models with different part numbers, but I can’t figure out what is actually different.
I’ve also seen references that the Triple STI does not work with compact cranks, even though is works with regular double chainrings. Any ideas why there would a difference? Seems like more a front derailleur issue than an STI issue.
Justin,
Your answer depends on the type of STI levers you are talking about.
Shimano Ultegra and 105 NINE SPEED levers are both double/triple compadible. You still need a triple crankset, BB, front and rear derailleur and longer chain if you want to make the switch.
Dura ace NINE SPEED requires either the correct double OR triple lever set.
Dura ace and Ultegra TEN SPEED levers are either double OR triple and ARE NOT interchangable.
105 TEN SPEED levers are double/triple compadible.
I hope this helps.
Since we’re on the subject…
I’ve got a 9-speed Bontrager triple, Tiagra front derailer, & 105 STI shifters. I’m considering switching to a 9-speed Bontrager double chainring setup.
At the shop where I bought the bike, they told me I needed a new crankset & BB, front derailer, and a new double-STI shifter ($200!!). With labor, about $600.
Another shop said all I needed was the crankset & BB, and front derailer. Does this sound right? Their guesstimate was about $400 before my discount.
Either way, I’ll get a written estimate beforehand. Thanks.
If you are mechanically inclined, you should take that the labor costs and invest in a bike tool kit and work stand. Then go to the park tool website and wrench away. It is not too hard to work on your own bike! and it’s quite satisfying as well. It’s just an idea 