I've got a triple OCR2 with 105 RD, Tiagra FD and Ultegra shifters. This is a 9 speed version. Thinking about swapping out the RD with an Ultegra RD-6600-GS. I've looked over Shimano's chart but not real clear if this 10 speed version will work properly with my bike. I've got a 26 cog in the rear.

Any feedback appreciated!

Thanks...

According to Peter White Cycles, the RD-6600-GS is backward compatible. https://www.peterwhitecycles.com/roadrear.asp

Thanks...I saw this page but wasn't entirely 100% convinced! When he says "37 teeth total gear capacity or chain wrap"...what does this mean?

edited: never mind...found that answer on SBrown's site.

What's wrong with the 105 RD? Is it short cage or long cage?

However moving on to one more item....sorry wish I was a bit smarter on these....My Giant has a braze on Tiagra FD. I can find a 6603 triple, which I think is also backwards compatible to my 9 speed, however it's a 34.9 clamp on. Will that work?

It's a long cage and kinda beat up. Since I can get the Ultegra for almost nothing as someone's take off, I've considering making the swap.

The rd will work fine but you need a braze on fd.