Chain too long after adjusting b-screw?

[ReapThaWhirlwind]

So I'm finishing up a build on a 90's GT Outpost Trail. I took the set from 7 speed up to 10 speed.

I got a Zee rear derailleur and a SLX iSpec B Shifter.

So I get into tuning the derailleur, and at first I can't get it to shift down into the lowest gear. I realize the integrated hanger probably needs to be pulled out and realigned. So I take the wheel off, do some fine adjusting, and sure enough it was perfectly aligned. So next it didn't want to shift into the last two gears. I check the barrel adjuster on the shifter and make sure the inner bobber is even, flush, neutral with the sleeve. I remove, retighten, and refasten the cable to the derailleur. I also noticed some skipping on the cogs as I climbed into the larger ones. So I begin to adjust the b-screw, pulling it out little by little, and finally it works its magic. I can shift all the way up, but then when I got back down after all the b-screw adjustment needed, the chain was way too long, and will need to be cut down some more.

Anyone else have this happen to them? lol

[ReapThaWhirlwind]

Interesting update to this.

I cut the chain down some more, and attempted to tinker with it for the kill. Sadly, I just couldn't get it to shift all the gears. Namely, I couldn't get it aligned with the 11t cog (10th gear). I could only get it to shift all the way up into the pro gear, and run silky smooth as it was before.

I noticed the derailleur is a little bulky, and I just don't think it's very compatible with the 90's frame and the integrated derailleur hanger. I tried to bend the hangar a number of times, but to no avail one way or the other.

I think it's the length of the integrated hangar that causes this. It's not long enough to give warranted space needed by the Zee derailleur to set properly. You have to wind the b-screw way up to get the clearance—but then you won't be able to transcend to (and run in) the pro gear smoothly. The b-screw needs to be relaxed quite a bit for this, and that doesn't provide good alignment specs with the 90's frame, due to the shortness of the integrated rear derailleur hangar.

Luckily, I have an Ultegra RD-6600. It's a 10 speed road. They say Shimano 10 speed Road and MTB aren't compatible, but I linked it up and it fit like a glove. In no time I was transcending all the gears and back. Shifter is an SLX m670. After some tinkering with the b-screw and the limit screws, and the cable tension, no skipping gears or anything.

This should make sense—since the pull ratio and spacing is the same per speed. It's the length of the derailleur hanger that makes up the differences. Ultegra has a few Shadow clutch components. And the Shimano Zee is marketed for use with a Shimano 105 10 speed cassette. I'd say the myth here is busted. So long as the derailleur can handle your top gear, mixing Shimano 10 speed Road and MTB should be doable once all the adjustments are right.