Bigger climbing cassette Shim 105 advice

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Alex321

Veteran
Location
South Wales
By far the easiest way for lower gears is to fit a grx 600 chainset 46/30 and grx front mech. The benefits are that if you run an 11/ 32 11 speed cassette the cassette isnt too gappy with huge jumps between ratios.

That's fine if you are happy with a lower top gear.

Many people are, of course. If you rarely use the top gear, you will probably be happy if it is a bit lower.
 

rivers

How far can I go?
Location
Bristol
By far the easiest way for lower gears is to fit a grx 600 chainset 46/30 and grx front mech. The benefits are that if you run an 11/ 32 11 speed cassette the cassette isnt too gappy with huge jumps between ratios.

You don't even need to do that- FSA Omega 46/30 works with a standard 105 front mech no problem. Easier and cheaper
 
Last edited:
By far the easiest way for lower gears is to fit a grx 600 chainset 46/30 and grx front mech. The benefits are that if you run an 11/ 32 11 speed cassette the cassette isnt too gappy with huge jumps between ratios.
Fine if you use band-on mechs. Braze-ons won't adjust far enough.
You don't even need to do that- FSA Omega 46/30 works with a standard 105 front mech no problem. Easier and cheaper
Similarly, only if band-on.
 

rivers

How far can I go?
Location
Bristol
Fine if you use band-on mechs. Braze-ons won't adjust far enough.

Similarly, only if band-on.

Braze-on R7000 105 mech with a 46/30 chainset
 

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Braze-on R7000 105 mech with a 46/30 chainset
Must have far greater range of adjustment than mine, then. Mine might - and I mean might - manage a 48...
Having said that, as I type, I'm remembering that I've just fitted a more modern mech, max chainring 50t. So if it were a double, it would just make a 46.
I'm cheating talking about this anyhow, as I run a triple! So 50-39-28 at the mo...
 

Ajax Bay

Guru
Location
East Devon
Must have far greater range of adjustment than mine, then. Mine might - and I mean might - manage a 48...
Having said that, as I type, I'm remembering that I've just fitted a more modern mech, max chainring 50t. So if it were a double, it would just make a 46.
I'm cheating talking about this anyhow, as I run a triple! So 50-39-28 at the mo...
Every extra tooth, or every tooth less, on the largest chainring requires (ideally) a front derailleur height change of 2mm. HTH (12.5/(2π))
Which reminds me, I should drop my FD 4mm as I've just replaced a 52 with a 50.
For ultimate flexibility, mind, I have a band-on/braze-on so my FD height range is in practice, 'limitless'.
 

Ajax Bay

Guru
Location
East Devon
will I need a new chain
If it's a new cassette, always pair it with a new chain.
Decide chain length based on large-large (not through RD) plus one inch.
 
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