Is this the Shimano short or medium cage derailleur?

[Mark1978]

Thanks for all the input people. Food for thought for sure. I think, as Will Spin says, the best option is to just get a new bike with the 11-32 pre-installed. I can just keep the Defy on the turbo throughout the summer in case it's raining.

I have no problem with spending the extra money on doing it properly to be honest. I'm an engineer, it's got to be right.

 

[Tangoup51]

I have no problem with spending the extra money on doing it properly to be honest. I'm an engineer, it's got to be right.

Resourcefulness is my secret to engineering. ^^

 

[Mark1978]

Resourcefulness is my secret to engineering. ^^

Yep, I have the resources, I'll buy the right stuff for the job.

 

[Winnershsaint]

As an alternative you could try a 12-30 cassette, a 30 works for me with a short cage ultegra.

Therein lay my problem. finding an eleven speed 11-30 cassette without forking out £160. If that was the only change I was going to make I'd have considered a Dura Ace cassette, but I was always going to go compact anyway so wanted to keep the costs down beyond buying new chainrings. When I'm back from France I'll keep the 50-34 up front and switch back to an 11-28 cassette, although I do have a brand new 11-25 in the garage.

 

[Milkfloat]

Yep, I have the resources, I'll buy the right stuff for the job.

That's not proper engineering, it is purchasing.

 

[Venod]

Therein lay my problem. finding an eleven speed 11-30 cassette without forking out £160

I must admit I haven't looked at whats available in 11 speed, I am still on 10 on the road/cx bikes, I have an 11-42 11 speed on the MTB a proper diner plate job.

 

[Mark1978]

That's not proper engineering, it is purchasing.

I could buy the tools to manufacture my own cassette and derailleur and do proper engineering, but then that's purchasing too.

 

[Tangoup51]

Yep, I have the resources, I'll buy the right stuff for the job.

I like to think Engineering as a challenge, using a credit card as your multi-tool is not the true mark of a great engineer. !!

 

[Milkfloat]

I could buy the tools to manufacture my own cassette and derailleur and do proper engineering, but then that's purchasing too.

A real engineer would make their own tools.

 

[Mark1978]

A real engineer would make their own tools.

OK, you win. I'm not skilled enough in mining or metallurgy to delve any deeper here.

 

[Milkfloat]

OK, you win. I'm not skilled enough in mining or metallurgy to delve any deeper here.

A real engineer would not let a lack of knowledge stop them, they would get stuck in then try and cover up their mistakes with sealant later

 

[mickle]

Yikes.

Only two things matter; 'max sprocket size' (the derailleur's ability to reach down far enough to influence the chain onto the bottom of the big sprocket and which is dependent on the geometry of the parallelogram) and 'tooth difference' (subtract the number of teeth on the smallest chainring from the number of teeth on the biggest chainring - and subtract the number of teeth on the smallest sprocket from the number of teeth on the largest sprocket and add these two figures together to get your total 'tooth difference') which is the dependent on the ability of the spring loaded cage plate to take up all potential chain slack. Also relevent (depending on the mech) is 'smallest sprocket' and 'front difference'.

'Max sprocket size' and 'tooth capacity' are listed on the box and in the installation intructions that came with your mech/bike. Or on the manufacturer's website: http://bike.shimano.com/content/sac-bike/en/home/components11/road/ultegra1/rd-6800-gs.html