Help me with a 105 rear cassette upgrade

[deanobeano]

Bit of a biking newbie here, so apologies if this question is daft...

I've got a second hand road bike with a 105 groupset (10 speed rear cassette 11-28T)

This bike is based in Southern Spain and it's bloody hilly here!

I would like to change the ?rear cassette to one that would make it a tad more easy on the climbs.

Could I get a 11-30T rear cassette fitted?.

Apparently, I have a short cage hanger (if that's the word).

Or, would it make more sense to change the front rings from 50/34?

Looking for the simplest solution, and was after your advice, before I walk into a bike shop and sound like a knob!

Oh, the simplest solution shouldn't be 'scrap the bike and buy the latest 12 speed £5k bike!!'

[OutInTheShed]

2 teeth on the back is not a very big difference.

It's best to work with Shimano part numbers where possible because a '105 reach mech' covers many things over the years.
Having said that, I can't remember mine.

A rear mech with a given cage has a 'capacity' to take up the slack of x-amount of teeth.
This is the difference between (biggest front + biggest back)-(smallest front + smallest back)

I have a 10 speed 105 bike, I've made it work with a medium cage and a 11-36 on the back, but I had to reduce the size of the big chainring on the front to do it.
My low gear is now something like 32 front, 36 back, which I find just about low enough for some hills around here.

I looked into fitting a proper long cage but none came my way for sensible money.
Some Shimano MTB cages don't fit, I found that out.
Also rear mechs are not interchangeable between MTB and road, the 'cable ratio' is different.

[Llandudno]

I’ve got a 34 on the back with my 50/34 compact. I can’t use 50 x 34/32 but wouldn’t want to anyway. There’s enough mech travel for everything else.

Bike shop might be able to fit one as a test.

[Your Dad]

105 10spd SS (SS is short cage and GS is long cage) rear mech takes max 30t so will be ok.

https://www.bike-components.de/en/Shimano/105-RD-5...

[WPA]

Your Dad said:

105 10spd SS (SS is short cage and GS is long cage) rear mech takes max 30t so will be ok.

https://www.bike-components.de/en/Shimano/105-RD-5...

Agreed, 11/30 on a short cage will be fine

[_Rodders_]

Just the question I had, thanks for asking and answering.

I don't know which cage I've got but going to assume short as its currently on 11-28.

Might fit 11-36 and just sacrifice the big ring, little ring combos.

I've done a couple of weeks in the Alps on the current setup but I'm 10 years older now and need to spin the legs a little more up the 20% bits.

[deanobeano]

Thanks for the replies.
Will take the bike to a local bike shop and look to fit a 11/30T rear

[OutInTheShed]

Llandudno said:

I’ve got a 34 on the back with my 50/34 compact. I can’t use 50 x 34/32 but wouldn’t want to anyway. There’s enough mech travel for everything else.

Bike shop might be able to fit one as a test.

I know a few people who've set bikes up with such combinations.

When they inevitably eventually push the right shifter too far, it's expensive and a walk home.
It's cheaper to buy the longer cage now.

[WPA]

_Rodders_ said:

Just the question I had, thanks for asking and answering.

I don't know which cage I've got but going to assume short as its currently on 11-28.

Might fit 11-36 and just sacrifice the big ring, little ring combos.

I've done a couple of weeks in the Alps on the current setup but I'm 10 years older now and need to spin the legs a little more up the 20% bits.

Or just run a mech extender

https://www.sjscycles.co.uk/gear-spares/sunrace-re...

[Barchettaman]

Sub compact cranksets are available and make a lot of sense for the ‘casual’ rider in hilly terrain.

https://www.sjscycles.co.uk/chainsets/165-fsa-omeg...

[OutInTheShed]

Barchettaman said:

Sub compact cranksets are available and make a lot of sense for the ‘casual’ rider in hilly terrain.

https://www.sjscycles.co.uk/chainsets/165-fsa-omeg...

I think it's worth deciding what is the lowest top gear you will be happy with.
And what low gear you need.
Personally, I'm not mega worried about top speed so a big ring of 46 is plenty for me.
But with a 32T small ring, that is still a lot of chain for the derailleur to absorb, when coupled with 11-36 on the back.

It works with a medium cage (GS), but it's beyond what Shimano advocate.

You can buy the side plates to lengthen the derailleur cage, or a whole after market cage in carbon fibre.