Upgrade 11-28 to 11-32

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guppy02
Posts: 3
Joined: 15 Sep 2020, 2:14pm

Upgrade 11-28 to 11-32

Postby guppy02 » 15 Sep 2020, 2:20pm

Probably a question asked a 100 times before however...

I am prepping my winter bike the cassette and chain are due replacement. I currently have a 11-28 installed however i want to see if i can get away with a 11-32 rear cassette.

I currently have the following Shimano 105 5800 172.5mm-50x34-11-28 setup.

Could i get away with this upgrade with my current derailleur with a potential extra couple links?

mattsccm
Posts: 3415
Joined: 28 Nov 2009, 9:44pm

Re: Upgrade 11-28 to 11-32

Postby mattsccm » 15 Sep 2020, 5:07pm

Depends on the rear mech. Short or medium. Most bikes with a 28 as standard come with a short.
That can work with care but cross chasing doesn't as you won't have the chain capacity.

Valbrona
Posts: 2339
Joined: 7 Feb 2011, 4:49pm

Re: Upgrade 11-28 to 11-32

Postby Valbrona » 15 Sep 2020, 5:12pm

If your derailleur is short cage, best to by a new one in GS flavour as per previous post. And you will need a new chain as well since it will have to be longer than your existing one.

NB A chain always has to be of adequate length to do big/big.
I should coco.

roubaixtuesday
Posts: 3298
Joined: 18 Aug 2015, 7:05pm

Re: Upgrade 11-28 to 11-32

Postby roubaixtuesday » 15 Sep 2020, 5:16pm

Will probably need a medium rather than short derailleur.

But depends on bike specifics. A hanger extender is a cheaper option than a new derailleur, which seems to work adequately for most people.

The chain is probably long enough (4 extra teeth = one extra chain link) unless it's right on the limit already. But probably sensible to fit a new one anyway with a new cassette.

If it were me, I'd fit the new cassette, see if the derailleur is adequate with the B screw all the way in. If not, new derailleur or hanger extender.

Be very sure to check on the stand that the chain is long enough in big/big before riding on the road. Otherwise accidental use of that combo will shred everything.

[I see I've already been beaten to it on the last paragraph by @valbrona]

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Tigerbiten
Posts: 2090
Joined: 29 Jun 2009, 6:49am

Re: Upgrade 11-28 to 11-32

Postby Tigerbiten » 15 Sep 2020, 5:23pm

The other question to ask is will you cope with the new cassette.
To up the size of the largest sprocket without adding another sprocket means some of the other sprockets need to be altered as well.
Check where the changes are in relation to your most commonly used sprockets.
If you suddenly get a very big step between gears in that range then you may not get on well with the cassette.
It also depends on how often you use the 50/11 gear.
If very rarely then maybe drop the 11 sprocket to add a 32 sprocket.
So something like a 12-32 cassette may give you better gear spacings.

Luck .......... :D

gregoryoftours
Posts: 1286
Joined: 22 May 2011, 7:14pm

Re: Upgrade 11-28 to 11-32

Postby gregoryoftours » 15 Sep 2020, 9:13pm

It should be ok as long as you don't have a short cage mech. I don't think a hanger extender increases the capacity of the mech, it just means that maximum sprocket size is increased which is not the same thing. I would have thought that capacity stays the same.

As you are presumably running 11sp the gaps between gears won't be bad with 11-32. I'd probably consider a new chain with a new cassette, unless it's not had much wear. To add a new link or 2 to a used chain isn't ideal. But as someone else has said you may just get away with not needing a longer chain. Obviously proceed with caution regarding that!

Brucey
Posts: 40650
Joined: 4 Jan 2012, 6:25pm

Re: Upgrade 11-28 to 11-32

Postby Brucey » 15 Sep 2020, 9:50pm

shimano 11s 11-28 goes

11-12-13-14-15-17-19-21-23-25-28

SRAM 11s 11-28 goes

11-12-13-14-15-16-17-19-22-25-28

IRD 12-32 goes (at vast expense)

12 / 13 / 14 / 15 / 17 / 19 / 21 / 23 / 25 / 28 / 32T

So the IRD 12-32 has the same ratios as shimano 11-28, but you trade the 11T for the 32T, and there is an effect on how cross-chained you are in some gears of course. The SRAM cassette has a 16T in return for bigger intervals between the larger sprockets.

The SRAM 11-32 cassette is like the 11-28 but you lose the 16T sprocket and gain the 32T one. The shimano 11-32 cassette is a bit weird and uses even tooth counts in the middle of the cluster , so the exact same ratios don't exist in the middle of the cassette.

Shimano 11-32 goes

11-12-13-14-16-18-20-22-25-28-32

Re RD, the 'medium' length cage is required for a typical 50-34 compact double and a 11-32 cassette. You can usually set up the shorter RD with a longer chain and a 11-32 cassette and it will work, but you will almost certainly get slack running in several of the small-small gears.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

guppy02
Posts: 3
Joined: 15 Sep 2020, 2:14pm

Re: Upgrade 11-28 to 11-32

Postby guppy02 » 15 Sep 2020, 9:59pm

I think its a short cage. I have tried to identify for sure however no model number is printed on the derailieur. Is there a way of identifying if it is SS or GS?

gregoryoftours
Posts: 1286
Joined: 22 May 2011, 7:14pm

Re: Upgrade 11-28 to 11-32

Postby gregoryoftours » 15 Sep 2020, 10:36pm

It will have the model number somewhere, all Shimano components do. It's probably on the back of the parallelogram assembly. Maybe the SS/GS isn't in the code, I guess if that's the case it's because the derailleur bodies are the same and the cages are swappable. But this is a picture of the two types -
gr15-shimano-rd-5800-105-11speed-rear-derailleur-both-psd_2.jpg

Apparently the GS is about 85mm between the pulley pivots and the SS is closer to 55. If Brucey says you can run an SS avoiding some gears then that's good. I'm running an xt mech on one of my bikes that is too short to take up all the slack in some combinations, but they really tend to be ones that aren't great chainline anyway, and it works absolutely fine in all of the other gears.

iandusud
Posts: 473
Joined: 26 Mar 2018, 1:35pm

Re: Upgrade 11-28 to 11-32

Postby iandusud » 16 Sep 2020, 8:03am

I have a bike running a short cage Ultegra rear mech with a 32 at the back paired to a 50/34 chainset. It works but requires careful setting up particularly with regard to the chain length. The chain needs to be as short as you can get away with whilst still being able to run from large chainring to large rear sprocket. With the chain any longer the top jockey wheel will foul the 32t sprocket. As Brucey says this will result in a slack chain if you try and run small chainring with small sprocket but as there is no need for this and even if you do it does no harm it isn't an issue.

guppy02
Posts: 3
Joined: 15 Sep 2020, 2:14pm

Re: Upgrade 11-28 to 11-32

Postby guppy02 » 16 Sep 2020, 1:16pm

I have taken a look it doesn't specifically say its a SS or GS just RD-5800. However its got to be a Short cage as the arm is short like the picture previously posted. I have seen a 2nd had medium cage on ebay so I might buy that. Otherwise ill just stick with my 11-28 i have ridden with a 11-28 for the past 5-6 years on both bikes with no issues (i ride steep climbs in Yorkshire) however i guess next time i ever upgrade its something to bare in mind.

My other though is maybe the 11-30 instead is it worth changing for any benefits?