So I'm road testing my new Retroshift shifter pods on my 126 mm rear triangle road bike. I'm using Shimano 105SC 7 speed levers with an older Deore LX rear dérailleur. The crank is an Ultegra 6503 triple. The Deore LX rear is not as crisp as I would like. And this is where I started think: it's either the 105SC levers, or it's a set up issue with the Deore LX rear. I'm running a Dura Ace 7400 Uniglide 12-25 7 speed cassette.
Here's an idea: What if I convert the cassette to a 12-21, change the shifter to a Dura Ace 7401, change the rear dérailleur to Dura Ace 7401. Would the rear dérailleur have enough chain wrap to keep the chain taut enough with the 30 tooth chainring on the Ultegra triple crank? Thanks for any opinions you can offer on the advisability of this build, from Bill.