10spd upgrade to 11spd

Mungecrundle wrote:

.... Well if it was my money I'd seriously be asking what does 11 speed give me that 10 speed doesn't? ....

Well it's obvious isn't it. The old one goes up to 10, but the new one can be turned up to 11. That's all the way to 11, not just 10. I'm afraid 10 doesn't cut it any more, not now that 11 has arrived.
Who, in their right mind, would be satisfied with only 10, knowing all the time that some people have achieved 11, which is at least one better. That's one better in every way, of course. It's called mathematics and it's simple, if you concentrate.

vonhelmet wrote:

I stand corrected. That's a bit of a change from past tech where pretty much any old mech would work!

Yep, bit of a pity - apparently SRAM will pick and mix a bit, perhaps not ideally but at least functional.

vonhelmet wrote:

You shouldn't need derailleurs, I don't think, unless there is something fundamentally different between 11 speed derailleurs and all others.

Alas I think there might be differences..

Forget about using Dura-Ace 7900 derailleurs with 11-speed levers. The derailleur’s shift-activation ratio is different for Shimano 11-speed rear derailleurs than it is for Shimano 10-speed rear derailleurs. Furthermore, Shimano 10-speed mountain and road rear derailleurs have different actuation ratios from each other, and the same goes for Shimano 11-speed mountain and road rear derailleurs. Prior to road 11-speed and mountain 10-speed, things were simpler; Shimano road rear derailleurs up through 10-speed and mountain-bike rear derailleurs through 9-speed all have the same activation ratio.

And your intuition is correct that a Shimano 11-speed shifter will not work well with a 10-speed front derailleur because the 11-speed shifter is designed to actuate the longer lever arm of Shimano 11-speed front derailleurs

Read more at http://velonews.competitor.com/2015/03/bikes-and-tech/technical-faq/tech...

Sounds like that might well apply to 105 unfortunately.

vonhelmet wrote:

You shouldn't need derailleurs, I don't think, unless there is something fundamentally different between 11 speed derailleurs and all others.

The cable pull is longer on the 11 speed 105, so the compatibility that existed between 9/10 speed derailleurs unfortunately isn't true for 10/11 speed. It's also longer on the new 10 speed Tiagra due later this year, so you won't be able to mix shifters and derailleurs from that with old 10 speed.

The benefit is that shifting is now slightly more accurate and cable stretch leads to smaller alignment problems.

bikebot wrote:

It's also longer on the new 10 speed Tiagra due later this year, so you won't be able to mix shifters and derailleurs from that with old 10 speed.

That so? That's a bit crap. I've got Tiagra 4600 on one bike and I'm happy enough with it, so was relieved to see they were sticking with 10 speed for the next revision as I figured it would mean a continuing supply of spares...

vonhelmet wrote:

bikebot wrote:

It's also longer on the new 10 speed Tiagra due later this year, so you won't be able to mix shifters and derailleurs from that with old 10 speed.

That so? That's a bit crap. I've got Tiagra 4600 on one bike and I'm happy enough with it, so was relieved to see they were sticking with 10 speed for the next revision as I figured it would mean a continuing supply of spares...

All the parts taking the brunt of wear and tear, cranks, cassette and chain should be compatible. It's just the derailleurs and shifters that have to be matched.

What might be interesting for the future, is whether the new Tiagra has derailleurs that are compatible with 11 speed 105, as with 9/10 speed today. I should take a look at the Shimano docs and do a bit of maths.