Changing cassette

jann71

Veteran
Location
West of Scotland
Looking for some gears advice please.

My current gear setup is shimano tiagra 9 speed. Triple on the front 30 / 39 / 50 and 12-25 on the back (on a 46cm Giant road bike)

As the bike needs serviced and possible chain replacement and new gear cable I'm thinking of changing the rear cassette.

I'm fine with current setup on the flat (happy spinner at least 80rpm) but I struggle on the hills especially when i'm tired.

Would I notice much difference changing to an an 11-28 or 11-32?

thanks
 

TheDoctor

Europe Endless
Moderator
Location
Stevenage
11-28 would essentially give you one gear below what you've got, and you'll almost certainly be fine with your current rear mech.
11-32 would give you a mad low bottom gear, that will get you up practically anything (Alps, Mont Ventoux, cliffs, brick walls etc)
However, you'd almost certainly need a MTB rear mech.
They're not all that expensive and would work perfectly with your existing gear levers, so worth considering.
 

maurice

Well-Known Member
Location
Surrey
I had a similar triple setup to you on my 8 speed Allez. I changed the rear 12-25 cassette to an 11-28 for touring in the alps with luggage. You do have get a noticeably lower first gear, which is a nice thing to have in reserve for steep or long climbs. However, you end up with some big gaps in the gear rations which can be annoying.

A Tiagra rear mech according to Shimano is only rated for up to a 27t cassette. I found mine works fine with a 28t, but 32t will be pushing it - you may need an mtb rear mech for that.
 

rogersavery

New Member
Try change front smallest chain ring for a 28 or a 26

It will be a much cheaper option (£10ish) and easyer to reverse. You will an allan key and a crank pulled to fit it.

Putting a 26 ring on the front and keeping the original cassette will give you a lower gear than 30 front to 28 rear

Most front detailers should just about cope, but it will probably mean you will only have 3 usable gears on the smallest chain ring (not a big issue really)
 

Nick_B

New Member
Try change front smallest chain ring for a 28 or a 26

It will be a much cheaper option (£10ish) and easyer to reverse. You will an allan key and a crank pulled to fit it.

Putting a 26 ring on the front and keeping the original cassette will give you a lower gear than 30 front to 28 rear

Most front detailers should just about cope, but it will probably mean you will only have 3 usable gears on the smallest chain ring (not a big issue really)

But if you're changing the cassette anyway during the service there is essentially no cost of going to 27 or 28 at the back.
 

PpPete

Guru
Location
Chandler's Ford
11-28 cassette is first step.

if not enough, then 28 ring on front

if still not enough.....custom built cassette, maybe 12-30 which is about as far as one can push the road mechs (as pointed out above they are only rated to 27T). Miche I think do one (expensive), or you can butcher a couple of Shimano HG50 cassettes to get near enough (although shifting ramps don't line up as intended)

Last resort, 26 ring on front, but if you keep the 50 ring that's really pushing the limits of the front mech too..... and the rear has humongous amount of slack to take up.
Everything still works (at least on mine it does) but be prepared for loud (and potentially expensive) noises if you ever try to run a crossed chain. Probably safer to invest in an MTB mech at this point.

I've only kept my 50/38/28 and 12-30 set up with a road mech because of vanity.
 
OP
jann71

jann71

Veteran
Location
West of Scotland
Thanks for the suggestions folks. Took bike the other day to LBS for service and got it back today.

We had agreed to change the rear cassette to an 11-28 but realised when I got home its an 11-32. (also have new chain)
They said something about it working ok as I have a long something, maybe cage?

My next question is - out of the 9 cog things at back is it best to just be using the middle 3 or 4 when I'm on the middle and big ring at the front as I now have a bigger jump between gears?

Thanks
 

Manonabike

Über Member
Thanks for the suggestions folks. Took bike the other day to LBS for service and got it back today.

We had agreed to change the rear cassette to an 11-28 but realised when I got home its an 11-32. (also have new chain)
They said something about it working ok as I have a long something, maybe cage?

My next question is - out of the 9 cog things at back is it best to just be using the middle 3 or 4 when I'm on the middle and big ring at the front as I now have a bigger jump between gears?

Thanks
I use whatever feels comfortable for the terrain when I'm in the middle ring, however, on the flat I mostly use the big ring and the smallest 3 cogs at the back, depending on how fast I'm pushing the pedals. If I have a strong headwind then I can either use the big ring with the 5th or 4th smallest cog, or the middle ring and the 3rd or 2nd cog. Having said that I think what is comfortable for me might not be for you but you will find your appropriate range and it will probably also change as you get fitter.

You have a long cage derailleur to work with the 32 sprockets -
 
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