Gears ratio - want to fit wider range rear cassette

[Colin_P]

Hello Technical Boffins,

I currently have the following on my road bike;

52/42/30 on the front.
12-23 over eight cogs on the back.
It has a STI'd Sora rear derailleur

I'm thinking of swapping the cog set to something like an HG51 with an 11-32 range.

To put things in context and why I'm wanting to do this; I have a Heart condition which is being managed with massive doses of Beta Blockers and Anti Arrhythmic Drugs and as a result I simply cannot push as hard up hills as I once was able to. Being on these drugs is like your Heart having half the oomph it should have. I'm still out there on the bikes everyday but rather than suffering the humiliation of having to get off and push on really steep bits of hill where once I would have grinded and powered up them, I'd rather spin some low gears even if I am only going to go at walking pace!

My Hybrid is lowered geared with the lowest being 28F 28R, so a 1:1 and even with that I can sometimes struggle on really steep bits so may be looking to sort that as well at some point. But is another thread.

Questions are (for the road bike);

1, Is the proposed 11-32 range feasible / usable. I don't want to mess with the front as it would be expensive where as a rear cog set can be had for £10.

2, Am I going to need to swap the derailleur to a medium or long cage version and get a longer chain? If so what should I go for (assume an MTB Sora equivalent)? Would a longer cage and wider cog spread work with the STI shifters?

3, Would a more sensible 11-28 bet better, accepting I may still struggle now and then and would this avoid having to change the derailleur ?


For anything I've missed or not thought of, any additional thoughts and advice welcomed.

 

[Peteaud]

My wife has an 8 speed road bike.

It has the 11-32 cassette, but with a Deore rear mech and longer chain.

She has the old 8 speed claris.

Works no problems.

 

[KneesUp]

I'm desperately unfit (well, I'm a bit better now, but pretty bad) and I have 42/32/22 on the front. I know you said you don't want to mess with that, but it was only £20 from decathlon and works perfectly well. It's not got a brand name, but it's aluminium and reasonably light.

You need to find the total capacity of your rear derailleur - it will be stamped on it somewhere. The total capacity is the maximum difference in cog sizes it can deal with. I would suspect that 11-32 will need a medium/long cage - I have that range (so my bottom gear is 22/32 - my legs go like a particle in the hadron collider) and have an Acera mech I got new for £13 off eBay - works fine.

 

[Colin_P]

Cheers Gents,

Also a question about chains

I'm used to old ones where you would have to use a splitter but I understand now that there is something called a magic link? Am I mis-understanding this? Do I need a special tool for these ?

 

[numbnuts]

What your after is a SRAM PowerLink Chain Connector
http://www.chainreactioncycles.com/sram-powerlink-chain-connector/rp-prod871

 

[KneesUp]

Cheers Gents,

Also a question about chains

I'm used to old ones where you would have to use a splitter but I understand now that there is something called a magic link? Am I mis-understanding this? Do I need a special tool for these ?

My current chain (cheap Shimano one) has a link that is designed to allow you to connect it once without tools, although with a little persuasion I've unlinked it and relinked it without tools.

 

[arch684]

you would still probably still need a splitter to remove links from the chain in order for it to fit but you don't need any tools to fit the quick link . have a look at some video's on youtube

 

[Colin_P]

Hmm,

These quick links, are they a weak link? Is it best too remove them, bin them and connect the chain up the old fashioned way ?

 

[Peteaud]

Hmm,

These quick links, are they a weak link? Is it best too remove them, bin them and connect the chain up the old fashioned way ?

No they are not a weak link.

Most swear by them. I still like the old shimano pin, but i am in the minority.

 

[ColinJ]

Hmm,

These quick links, are they a weak link? Is it best too remove them, bin them and connect the chain up the old fashioned way ?

I never managed to break one, even when I weighed over 16 stone, and was standing on the pedals to force my way up gradients greater than 20%!

 

[Nigelnaturist]

@Colin_P a most modern road RD's can do up to 30-32th on the rear. depending on your inner front ring BCD if its 74mm you could try a 28th inner ring (£10), my 105 FD can cope with a 26/38/50 and the 105 RD can cope with the 39th range 24 front and 15 rear (12-27). If your struggling try and get a cassette starting higher say a 12th as the 11th will hardly get used, this will give you a better spread on the back.

 

[DaveS]

Colin-P, I hope there is some help for your heart. I had open heart surgery in January and had a new aortic valve. Before, I could not manage stairs any longer. Now I am regularly riding 25plus miles in hilly terrain with a single speed. I wish you well.

 

[Nigelnaturist]

Most shimano parts i.e. gears RD's will fit both road and m.t.b. (there are a few exceptions).
I know you said you don't want to change the chainset, but this is an option as its not to expensive, http://spacycles.co.uk/products.php?plid=m2b0s109p2000 at £35, you will probably need a new BB however at up to £20.
Though this is a better set @£75 with rings 24/34/46 if you want http://spacycles.co.uk/products.php?plid=m2b0s109p2801, this is still only giving a maximum of 22th on the front, so no change there.
I hope this is going to help this first chart are the gear inches for each of your gears I think.

This is what your proposing with the 11-32

With a 24/34/46 front and your current cassette.

The same set up but with a 12-25 cassette

.

If I was gearing it for that sort of range this is what I would probably do, it gives a good low gear pretty much the same as the 30x32 (1/2" difference), ok you lose on the high gear bit, but thats not the issue, other advantages, you can use almost any GS (medium cage) road RD and almost any road triple FD, though those that say a max of 22th range would be better than those with 20th, though I have not tried one with 20th capacity to confirm this, however as your Sora is 8sp I will assume its an FD3303 model which has a 22th capacity.

The % figures on the right are the percentage change of the rear gears. the closer these are the easier the steps are between gears,

 

[Dogtrousers]

It looks like @Nigelnaturist has answered most of your questions. It's just a case of whether your rear mech (a) can cope with the largest sprocket and (b) can cope with the extremes of range between big-big and little-little.

But a more general point: You don't need to justify wanting an uber-low bottom gear and a mega-wide gearing range. It's not a badge of shame, it's just good old common sense! If you want it: get it. (And it also follows, if you want super close-ratio knee-breakers, have those instead!)

Anyway, best of luck with your project, and your medical condition.

 

[Nigelnaturist]

Just to go along with what @Dogtrousers says, don't think of the inner ring as a last resort to climbing, get on the inner ring and use the middle part of the cassette as opposed to the low gears on the rear and the front middle, as this will give you many more options whilst climbing.