Bigger climbing cassette Shim 105 advice

[Alex321]

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]

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

 

[DCBassman]

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]

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

 

[Venod]

I use 11/36 cassette with 46/34 chainwheels and medium cage 105 derailleur on my CX bike, no problems.

 

[DCBassman]

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]

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'.

 

[HumpTdumpty]

You can and I have, just need a drop link to take the rear changer way from the biggest cog
View attachment 662411

Hi Neil - so I’m tempted - my mid range 105 mech with a goatlink - for a 11-40 or 11-42 will I need a new chain to be safe do you think ?

Regards Humpty

 

[Ajax Bay]

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.