Gearing compatibility - will this work?

[DMC3000]

Will a 105 road mech work with 8 speed gearing as long as I use an appropriate shifter & chain? Here's two options I'm looking at and I'm not sure which, if either, would work:

18t chainring (Heatsink on middleburn RS7 crank)
Shimano Sora HG50 8 Speed Road Cassette 12-21
8 speed chain
105 5700 10 speed mech
8 speed rapidfire (not sure what)
or

18t chainring (Heatsink on middleburn RS7 crank)
Shimano 105 5700 10 Speed Road Cassette 11-25
10 speed chain
105 5700 10 speed mech
zee 10 speed shifter

I'd prefer to run 8 speed but not sure if the chain will be too wide for the mech or if there's other issues to consider.

 

[scottproonly]

Re:

You don't have to use an 8 speed chain for it to work! I use a 10 speed chain on a 9 speed setup and its perfect!
Kes

 

[cce]

I've got a sneaking feeling road and mountain 10 speed are incompatible, shifter/mech wise

 

[legrandefromage]

use road specific flat bar shifters for the ten speed

use a nine spd chain if using the 8spd system

but, the 10spd mech may not do the 8spd shifting - cable pull ratio ans all that

 

[DMC3000]

Re: Re:

It makes sense that the narrower chains will still work on wider spaced cassettes and not the reverse but I hoped to avoid 10 speed chains.

You don't have to use an 8 speed chain for it to work! I use a 10 speed chain on a 9 speed setup and its perfect!
Kes

 

[mattr]

The only non compatible thing up there on either set up is the zee shifter. Need a road 10 speed. (R700?)

The 8 speed chains *should* work on the 10 speed mechs but might be a bit noisy, as stated above, 9 will work just as well.

 

[mattr]

18t chainring (Heatsink on middleburn RS7 crank)
Shimano Sora HG50 8 Speed Road Cassette 12-21
9 speed chain
105 5700 10 speed mech
8 speed rapidfire (not sure what)
or

18t chainring (Heatsink on middleburn RS7 crank)
Shimano 105 5700 10 Speed Road Cassette 11-25
10 speed chain
105 5700 10 speed mech
r700 10 speed shifter