Cassettes and gearing

[DCBassman]

I'm actually rather restricted, because I try very hard never to mix with traffic. Basically it's following old railway lines.

 

[Illaveago]

Ah! A cunning plan.

 

[SirDickieBird]

Sora 8 speed on my Carrera and fitted an 11-32 cassette. LBS said it "just" fit but was fine.

 

[DCBassman]

That's good to know - will get new cassette and new chain together.

 

[DCBassman]

Am really hoping that will work on mine - technically, according to my research, my rear mech is a Sora GS medium cage and can take max 27t sprocket. Mine is also a triple-chainring setup, and that apparently makes a difference too...
When funds permit, will take it to the LBS and have a chat.

 

[T4tomo]

Have you worked out what your biggest rear cog is yet? And yes being a triple will make a difference, it's all down to the difference between you big big and small small combo's. But unless you know what's on there at the moment it's blummin hard to give you any advice.

 

[ColinJ]

I am a fan of low gears for climbing but if you nearly always stick to railway paths and there is only short climb which has defeated you, is it really worth bothering with changing your gearing? If you stick at it you would probably eventually manage it using your current gears, and if not it only sounds like a minute or two of walking with your bike.

Mind you, perhaps having lower gears would tempt you out onto some of the fine hilly roads that you have down there? I am heading down to Devon on Saturday and am looking forward to checking them out for myself, armed with my trusty 28/30 grovelling gear!

 

[DCBassman]

Apologies for not yet dicovering tooth numbers - it's a bit wet here right now!

 

[DCBassman]

To be clear, i try and stick to paths rather than ever mix with traffic if I can help it. The flatness is, locally, a bonus!

 

[DCBassman]

Right, I've been counting teeth, and the current cassette is a 12-25.

 

[mjr]

Then if your front chainrings are 50+39+30 like current Scotts, I reckon http://gear-calculator.com/?GR=DERS...15,17,19,21,23,25&UF=2135&TF=90&SL=2.6&UN=KMH is your gearing, giving a range of 32.1 to 111 gear inches. If you could get 27T in the rear, bottom gear drops to 29.7 inches, or if you can get 32T there, it would be about 25 inches, only slightly higher than the notorious two foot gear

 

[DCBassman]

As far as I can ascertain, the max allowable is 27T for this arrangement, so that's the one to go for.
Noob question: what's notorious about a two-foot gear?
Will have to have a measure...but as mjr says, it's a triple, which alters things. As a standard double, it could go to 32, I think...as a triple, probably not.

 

[mjr]

what's notorious about a two-foot gear?

It's also known as walking... but also, 24 inches is seen as fairly easy pedalling for all but the most extreme situations (extremely steep hills, recumbents, laden cargo bikes and so on).

 

[DCBassman]

D'oh, 2 foot...

 

[mjr]

[QUOTE 4943689, member: 9609"]why ever not, the chain will be happier going from 30 to 32 than 30 to 25[/QUOTE]
Yes but the problems may come if you ever slip into cross-chaining and now have to either fit the chain around a 32 and a 50, or at the other extreme, hope the derailleur can take up enough slack when it's only around an 11 and a 30. It's more likely to encounter the problem of not covering both extremes on a triple setup.