Short Cage Derailleur

Taxuser1

There's not much clearance between the '32 and the RD hangars. I'm wondering does it require a longer rear derailleur? I had a compact Shimano 6800 but changed to a 53 x 39 6750 but retaining the 6800 RD. it does work but it could do with dropping a little further down. Has anyone had any issues with larger gear ratios. Seems right at the edge of the gearing ratio that high ?

Subcomandante Marcos

Taxuser1 wrote: »

There's not much clearance between the '32 and the RD hangars. I'm wondering does it require a longer rear derailleur? I had a compact Shimano 6800 but changed to a 53 x 39 6750 but retaining the 6800 RD. it does work but it could do with dropping a little further down. Has anyone had any issues with larger gear ratios. Seems right at the edge of the gearing ratio that high ?

In general, you need a long cage derailleur to run a 32t cassette.

Eamonnator

Did you add a few links to your chain?
That might be part of your problem.

niceonetom

Maybe a washer between derailleur and hanger would help.

Unknown Soldier

Taxuser1 wrote: »

There's not much clearance between the '32 and the RD hangars. I'm wondering does it require a longer rear derailleur? I had a compact Shimano 6800 but changed to a 53 x 39 6750 but retaining the 6800 RD. it does work but it could do with dropping a little further down. Has anyone had any issues with larger gear ratios. Seems right at the edge of the gearing ratio that high ?

I'm surprised you got any clearance with a short RD and 32t combo.

I wouldn't worry about "not much clearance". It either clears it or it doesn't, as far as I can tell.

You would need an extra link in the chain though for the FD. And unless the bike came with a 32 on the back you probably should have added one then too.

I read somewhere recently that is you are in the big cog on the front and smallest on the rear, the RD should hang nearly straight at 6 o clock. And when you move up to the large 32 on your rear, as long as there is still some S bends and it is not "straight" you should be OK.

iwillhtfu

Subcomandante Marcos wrote: »

In general, you need a long cage derailleur to run a 32t cassette.

The newer 5800/6800 series is capable of taking a 32 cog with a a short cage RD.

OP I'd say you need to add a link or two to your chain or a new chain.

Subcomandante Marcos

iwillhtfu wrote: »

The newer 5800/6800 series is capable of taking a 32 cog with a a short cage RD.

OP I'd say you need to add a link or two to your chain or a new chain.

I don't agree. Shimano removed long/medium/short and replaced them with short/medium but in reality what they did was just take long out of the road range.

The closest thing to an old Long Cage Rear 105 is now a DORE LX 11 speed long cage which comes with the "shadow" feature which make it very, very quiet.

Current Shimano "long" cage rear road derailleurs are identical to the old "medium" in capacity.

If you want to run "wide" gearing you're better off either installing a shimano MTB rear mech or switching to SRAM and using APEX.

My 2 cents anyway.

Alek

you're better off either installing a shimano MTB rear mech

It will not work with STI (road) shifters, at least for 10 and 11 speeds.

I've researched this recently and many people seem to successfully use short cage mechs with 32 cogs (not only the latest Ultegra, but also older ones) - it apparently depends on the hanger and frame geometry, but often works.

Subcomandante Marcos

Alek wrote: »

It will not work with STI (road) shifters, at least for 10 and 11 speeds.

I've researched this recently and many people seem to successfully use short cage mechs with 32 cogs (not only the latest Ultegra, but also older ones) - it apparently depends on the hanger and frame geometry, but often works.

I totally forgot they changed the pull ratio of the newer MTB derailleurs.


I'm running a 10 speed Deore LX rear mech with a mostly 105 groupset on my tourer but I'm using bar end shifters in friction mode so that explains that.

iwillhtfu

Subcomandante Marcos wrote: »

I don't agree. Shimano removed long/medium/short and replaced them with short/medium but in reality what they did was just take long out of the road range.

The closest thing to an old Long Cage Rear 105 is now a DORE LX 11 speed long cage which comes with the "shadow" feature which make it very, very quiet.

Current Shimano "long" cage rear road derailleurs are identical to the old "medium" in capacity.

Sorry but you're wrong there but then again so was I.

The new 5800 will run a 32 tooth on a medium rear derailleur according to their marketing blurb anyway.

Taxuser1

the short cage 6800 will take the 32 with a 53/39 on front - with a fair bit of tweaking. there's a slight rub, but not enough to annoy. the gap is minimal between the '32T but it's definitely doable.

youtheman

I just bought a new Di2 bike recently. For 15 euros extra I could have specified a Long Cage (GS) derailleur to allow me use a 32t cassette. I was toying with the idea of going for the long reach derailleur, but using a 28t cassette for normal use, and just changing to 32t cassette for those 'special trips'. But I didn't go for that option in the end.

I then thought of purchasing a long reach DR as a 'spare', and change out as necessary.

Then I looked up the Shimano Parts manual for the DR (available on the internet), and it shows the parts that need to be changed to modify the existing DR from Short Cage (SS) to Long Cage (GS). You'll need and outer and inner plate (the plate is the 'cage' that holds the jockey wheels) plus a Plate Axle Assembly (the spring and pin). For my RD-6870 the parts amount to 41 euros on-line. Plus I think you'll have to change the chain as well.