Upgrading a Sram cassette from 12 27 to 12 32

[Charlie Chester]

Hi

I've got a Dolan road bike with Sram Rival gear set. It's got a 12 27 cassette on the rear and I have seen that there is a lower geared cassette on the market at 12 32. Has anyone upgraded to this and if so any difficulties found?

I'm thinking will the chain be too short? Will the rear derailleur be long enough? These just a couple of questions that people have suggested>

 

[Rickshaw Phil]

Having a look at the SRAM website they state a maximum sprocket size of 28 teeth for Rival. (2010 Tech Document Here).

If you really want that 32 tooth 1st gear it may be possible to fit a mountain bike rear mech (I believe some of the pro's have started doing this for serious mountain stages) and yes you will need a new chain as the existing one won't be long enough.

I'm sure others with more experience will be along shortly with better advice than I can give.

 

[Hacienda71]

It will work with an Sram Apex rear mech which is specifically designed as a road mech to cover that range. You will need to measure your chain as usual i.e. round the two largest cogs plus two full links.

 

[TheDoctor]

SRAM uses a different cable pull to Shimano, so don't go down the MTB mech route.
What you want is an Apex rear mech - it's designed to do a 11-32 cassette.
And yes, you'll likely need a new chain.

EDIT - Bugger, too slow!

 

[Rickshaw Phil]

^^^There, what did I tell you.

(BTW TheDoctor, SRAM first introduced the 1:1 pull on their mountain bike range).

 

[TheDoctor]

True, but I don't know for sure whether their MTB and road rear mechs are interchangeable, whereas I do know that Apex will work.
It certainly wouldn't surprise me if an Apex mech is essentially, say, an S9 MTB mech with a different sticker on!!

 

[Rickshaw Phil]

True, but I don't know for sure whether their MTB and road rear mechs are interchangeable, whereas I do know that Apex will work.

Fair enough.

It certainly wouldn't surprise me if an Apex mech is essentially, say, an S9 MTB mech with a different sticker on!!

I wouldn't be surprised either to be honest.

 

[Charlie Chester]

Hi

Thanks for the replies brilliant forum.

I was looking on the Sram web site and saw this page. When you hit the Specifications tab you see that it states it should work with sram rival! Strange.

So from whats been said so far on this thread it looks as though if I change my rear mech to a sram Apex and get a new chain I could use the 12 32 rear cassette? My chain looks stretched anyway so a new one of those would not be a bad idea. Would the Apex rear Mech work Ok with the Rival double tap shifters? I know that might sound a silly question to the experts? Is the 10 speed the thing you shouldn't change?

 

[Hacienda71]

Your shifters will work fine with the Apex mech.

 

[TheDoctor]

All SRAM stuff is 10 speed, I think. I'm sure the Apex mech will work with Rival levers.
That spec page you link to is talking about a whole range of cassettes, not just the 12-32T one.
It's always the rear mech that is the limiting factor for the size of cassette.

EDIT - Too slow again!!!!!

 

[Charlie Chester]

OK so to get the lower gear it's a new cassette, rear mech and chain. Just got to think now if the price is worth the gears.

 

[TheDoctor]

One question. You are using a 34T inner ring on your chainset, aren't you?
If not, getting one is the cheapest way to drop your gears.

 

[Charlie Chester]

The Doctor

Yes I'm using a 34 now.

My problem is I'm a big fella and find the hills hard. My last bike had a better lower gear being a 30 front and 26 rear. According to an app I have on my phone my set up now in the lowest gear is like being in second from lowest on the old bike. To get the same for my 34 front I would have to get a 29 on the rear but the only options are 28 or 32. I'm thinking that it would not be worth the expense for 1 tooth!

 

[TheDoctor]

Ahh, you'd not notice one tooth.
I found it a bit hard going from a triple to a compact. It does get easier if you keep at it.
Is the cassette and rear mech you have quite new? You could always flog it, and put the proceeds towards new bits.

 

[Charlie Chester]

I have had the bike about 2 year now but nothing wrong with the cassette or mech. The chain has seen better days! Its an option to re coop a bit.

Things have gotten easier but I feel that I need that extra gear and on the face of it the 32 would give me that. It also means that on the faster undulating roads I could stop in the large chainring that little bit longer as well.

The best option would be to cut out all the nice food an beer and lose loads of weight, but where is the fun in that!!

Thanks again people I'm well impressed.