Bigger climbing cassette Shim 105 advice

HumpTdumpty

HumpTdumpty
Location
Uk
Hi All got a Shimano 105 11-32 cassette need a bigger climbing gear will a 11-34 do the job ? I’m no KOM type just don’t want to feel like I’m running out of gears on a challenging climb - Was thinking of also adding a goat link also?

I’m no expert so any thoughts I’m assuming I will need to increase my chain size also ?

Or is there an 11-40 type option that’s compatible without rebuilding my new Ribble CGR 725 completely?

Any help much appreciated

Regards Hump below is my existing set up that the bike came with.

B05A44CA-A367-4D19-9EA7-7252D28A23B3.jpeg
 

T4tomo

Guru
its 6% easier on 34-34 than 34-32. Only you can know if this is enough, but you will tell a difference. Your rear derailleur will cope with this. If you want to run a 40 or 42T gravel option you will need a long cage gravel derailleur RD-RX812 is the long cage one.

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Joffey

Big Dosser
Location
Yorkshire
Hi All got a Shimano 105 11-32 cassette need a bigger climbing gear will a 11-34 do the job ? I’m no KOM type just don’t want to feel like I’m running out of gears on a challenging climb - Was thinking of also adding a goat link also?

I’m no expert so any thoughts I’m assuming I will need to increase my chain size also ?

Or is there an 11-40 type option that’s compatible without rebuilding my new Ribble CGR 725 completely?

Any help much appreciated

Regards Hump below is my existing set up that the bike came with.

View attachment 661977

Presume running a 32 on he back you have a med or long cage rear mech? I'd just stick the 43 on and see how you go with regards to chain length. Even if it is tight just remember not to ride in your 43 rear with your 50 at the front.


If it's too tight then get a longer chain.
 

Alex321

Veteran
Location
South Wales
You won't be able to go any bigger than 34 with a 105 mech. That is as much as the longest cage 105 mech will handle.

But there are gravel mechs which are compatible with 105 shifters, and which would cope with cassettes going up to 40 teeth or more (as suggested by T4Tomo above), so you wouldn't have to rebuild the whole bike, just a new mech, cassette and chain.
 
Location
Northampton
You have 2 options.
1. Change the rear cassette to 11-34. With this, you will need to change the derailleur and chain. Some says that you can add a piece to make it long cage. I have personally not done it.
2. More expensive option is to change the front mech at the same time to triple, 50, 39,30. But you will have to change the crank set, derailleur and shifter etc.
Personally I would not do it. But it is an option. I have an old Btwin Triban 3. Just for the fun, I changed it to Claris 9 speed and put 11-34 rear cassette. Very good gear ratio. Easy to climb. Jump is too big and clunky. But I did it myself so can not complain.
 

Alex321

Veteran
Location
South Wales
You have 2 options.
1. Change the rear cassette to 11-34. With this, you will need to change the derailleur and chain. Some says that you can add a piece to make it long cage. I have personally not done it.
2. More expensive option is to change the front mech at the same time to triple, 50, 39,30. But you will have to change the crank set, derailleur and shifter etc.
Personally I would not do it. But it is an option. I have an old Btwin Triban 3. Just for the fun, I changed it to Claris 9 speed and put 11-34 rear cassette. Very good gear ratio. Easy to climb. Jump is too big and clunky. But I did it myself so can not complain.

He has rather more than those 2 options, as already outlined above by various people.

And option 1 will not require a change of derailleur. If he already has a 32 tooth cog, then he has the derailleur that will officially handle up to 34 tooth. The smaller one officially doesn't go beyond 28.
 

cyberknight

As long as I breathe, I attack.
Sub compact double chainrings?
 

Dogtrousers

Kilometre nibbler
A 34t cassette is the easy option, and it's definitely noticeable (well I found it so anyway).

All the other options* involve significantly more faff and expense so it might be worth starting out with that and seeing how it goes.

* Apart from going for a 36T cassette which would be about the same, but has the downside that it may not work.
 
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wafter

Über Member
Location
Oxford
As others have said 34 is as large as you'll officially get away with; if you're running 32 already your RD might handle 34; meaning you'd just need a longer chain. Considering these cassettes are typically around £60 it doesn't seem like a great value mod for 6% lower gearing.

Assuming you have the standard 105 50/34 crankset you could look at the 46/30 GRX 600 crankset which would drop your gearing by about 13 on the small ring (welcome) and 8% on the big ring (probably not noticeable) however I think you'd also need to change the FD to a GRX item as the chainline spacing is different to 105.. so again probably not cheap.

It's also worth considering the crank swap from the perspective of rideability too - my CdF (near enough) has 105 throughout and I find I'm constantly skipping across the chainrings as I want to be in the middle of the range. Dropping to smaller chainrings would mean I could go lower on the big ring before having to change (as well as giving me a welcome lower end) so I'd probably have to shift on the FD less.
 
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Legs

usually riding on Zwift...
Location
Staffordshire
Holy Moses, you could ride up the side of a house on 34x32! I used to ride around the Staffordshire Moorlands on 39x23 with a 3st child on the Hamax seat! Do you live at the top of Rosedale Chimney?
 
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