Hi,, this has probably been asked before, but I can't find it.  I am after some advice to change Shimano 105 rear cassette from my present , 10 speed 11-28,,,   to either 11-30 or 11-32 , to make it a little bit easier for my 71+ year old legs to push up hills (love riding the hills). 

I have read about probably needing a longer derailleur , but I'm not sure what to buy , also would I need a longer chain ?          I know I'll also have to buy a chainwhip and a Shimano spanner.  

Can anyone please advise me what to buy for this change and maybe best places to buy either local or online .

Thanks for any help   

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Shimano tells us the RD has a max capacity on the rear of 28t but as Paul mentioned it can be pushed to 30t. My understanding is 32t is not normally possible without modifications. The simplest fix would be to swap  your 52/36 cranks for 50/34. 

I have fitted 11/32 to my 105 short, the chain lenght needs to be perfect as it will be too tight on big gears and too loose on small gears, there is like 1 or 2 link in it.

The real problem come if you chain falls off your jockey wheels will go into the cassette and ruin them.

They do say that cycling never gets any easier...just faster.

Shimano base their 'biggest tooth' standard on an outdated horizontal dropout market. Most bikes these days have a vertical drop out which instantly creates a bigger gap between the largest cassette point and the upper jockey wheel.

This is why I can run 32 cassette on DA9000 rear mechs no worries but it is 'against' Shimano's 'recommendations'.

I did exactly what you are trying to do early this year in prep for 3 Peaks.

I had all Ultegra Di2 compact with an 11-28 and the 11-32 didn't work for me. The teeth on the jockey wheel were touching the biggest cog. Not sure if it depends on the frame. Mine's a Pinarello.

I ended up upgrading by buying an 11sp medium cage rear derailleur, 11sp front derailleur, an 11-32 cluster and a new chain.

It all works well with my 10sp Ultegra levers and 10sp Ultegra compact crank. Just a tiny bit more chain rub than before with my 10sp 28t but that's being really picky.

The front derailleur may be required depending on the firmware on your existing front derailleur, the firmware of the two derailleurs needs to be compatible or it just wont work. I'm not sure how to check it without just buying it and trying it out. (what I did)


Alex, did you have the B screw all the way in? Did you try a longer B screw? They can be sourced from most hardware stores for 50c approx.

It can depend on the frame hanger when fitting 32 cassettes with short cage 11spd shimano rear mechs. Most frames today come with vertical drop outs. This better suits larger cassettes with short rear mechs. Older steel bikes typically have horizontal drop outs.

Most late model Giant, Trek and Specialized can handle a 32 with short cage it from what I have seen and installed.

Ive 10spd on 2 bikes. One has a 5700 105GS rear mech and it works fine with a 34 XT 10spd cassette on my Cannondale CAAD9.

Yeah, I tried all the way in and then tried putting it in the other way around so the derailleur had good extension.

To get it running smoothly I needed to shorten the chain to extend the rear even more but then it was too short when crossed up on the big ring, big cog.

It wasn't terrible but I like it to run silky smooth so it was really annoying me, esp when going up hills when I am going slow enough to hear and feel everything.


Thanks for the replies guys. Changing to 36/32 combo would actually be slightly lower ratio than 34/30, but to save hassle, going with a new crank may be the easiest option and the difference is negligible. The price of $200 for a new crank seems to be the cheapest option, as replacement rings are $200+ and consensus says I can't go bigger than a 30 on the rear without getting a new RD as well. That's a fair outlay to get a 6% difference...

If you're on Facebook join a group called 'Bicycle Market'. I've seen riders swap cranksets on there plenty of times; mid-compact cranksets like yours are very popular at the moment. 

You're right.  The term "mid compact" refers only to the chain rings, the crank itself is a full compact.

How low do you want to go? Sugino Compact Plus+. Uses a 110 BCD for the outer chainring and 74 BCD for the inner chainring. You can get various combinations from 52/36 down to 44/30. Maybe a 48/32 will meet your needs?

With the Sugino you can fairly easily change your gearing depending on the ride by having a couple of different chainring combinations.

44/30? Will it fit a Stages though?

Would those rings fit on a Shimano or Sram compact I wonder?


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