12-30 Rear cassette from an 11-28.

[pplpilot]

I have a Ultegra 11-28 rear cassette and an SRAM Force rear derailleur. Cycling in the lake district this last weekend has sort of convinced me I'd like to get a little easer gearing (for the time being at least!)
is it possible to go to 12-30 without changing the chain and/or rear derailleur? I've had 2 conflicting bits of advice from 2 Local bike shops.

 

[SquareDaff]

How long is a piece of string (or in this case your chain)? Based on my experiences with a 105 mech (a short deraileur) and 112 links on the KMC chain I'd say a 28 rear was the lowest I could go to.

 

[Peteaud]

It depends on the bike and the hanger.

Some will, some wont.

 

[HLaB]

I think SRAM derailleurs can handle up to 32t cassettes but check their specs.

 

[Peteaud]

I think SRAM derailleurs can handle up to 32t cassettes but check their specs.

Think that the wifi ones, i think the standard as different although i am not up on the Sram stuff.

 

[RecordAceFromNew]

It depends on the Force model, but the minimum is 28T max cog, 33T wrap range. However, since such figures are nearly always conservative why not just check?

If the OP can see (or make, via adjusting the B screw, see this) no less than 4mm clearance between the 28T and the top jockey wheel then it will most unlikely to have any clash issue with a 30T (because the radius of a 30T sprocket is 4mm greater than the 28T). Regarding wrap range, it is also most unlikely to be a problem (and if it is a problem it will only manifest itself in small small, which probably won't get used) if it is a double chainset up front (because 30-12 + 50-34 = 34 only just above 33), and if the chain length is just right (i.e. not too long).

Regarding whether the existing chain is long enough (assuming it is not worn, which if it is should obviously be replaced along with a new cassette) for the 30T, it is easy to check with a chain length calculator.

 

[antnee]

Now this thread is the nearest I can find to my problem I changed my 8 speed 11-28 sprocket cassette to a 9 speed 11-30 cassette but am finding that the chain is skipping when pedaling in the 50 chainwheel and 11 cassettee sprocket. Though the R D is a sora the set up worked fine with a 8speed 11-28 cassette and the 50-39-30 chainwheel to get the 11-30 9 speed to work I put new 9 speed chain on and using the chain caluculotor? (the thing that tells you how longer chain you want) it told me 55 links but could not get the set up right till i'd Reversed the B screw as the jockey wheel was catching the 30 sprocket when on the 30 chainwheel (this is a bail out gear as never yet used it on road test) and I've realiesed that the more you wind in the b screw it pases the point of contact on the Derailleuer hanger this is when you've got a longer 4mm screw as the exsisting one is too short! So I now think the derailleuer mec on the rear needs a bigger throw, Longer derailleuer body more expense and I thought I'd cracked it might have been easly to leave it as wrapping the handlebar tape was a
Trauma in itself! Perhaps I need a longer cage Rear Derailleuer Though Its only 2 teeth bigger it must just be to big.
How many links should my cassette Sprocket be engaging at any given time and is this the reason for the skipping !
Regards All

 

[tincaman]

Give it a go, cheap Tiagra 10 speed 12-30 cassette from CRC £15.49

 

[jowwy]

Now this thread is the nearest I can find to my problem I changed my 8 speed 11-28 sprocket cassette to a 9 speed 11-30 cassette but am finding that the chain is skipping when pedaling in the 50 chainwheel and 11 cassettee sprocket. Though the R D is a sora the set up worked fine with a 8speed 11-28 cassette and the 50-39-30 chainwheel to get the 11-30 9 speed to work I put new 9 speed chain on and using the chain caluculotor? (the thing that tells you how longer chain you want) it told me 55 links but could not get the set up right till i'd Reversed the B screw as the jockey wheel was catching the 30 sprocket when on the 30 chainwheel (this is a bail out gear as never yet used it on road test) and I've realiesed that the more you wind in the b screw it pases the point of contact on the Derailleuer hanger this is when you've got a longer 4mm screw as the exsisting one is too short! So I now think the derailleuer mec on the rear needs a bigger throw, Longer derailleuer body more expense and I thought I'd cracked it might have been easly to leave it as wrapping the handlebar tape was a
Trauma in itself! Perhaps I need a longer cage Rear Derailleuer Though Its only 2 teeth bigger it must just be to big.
How many links should my cassette Sprocket be engaging at any given time and is this the reason for the skipping !
Regards All

you can't use a 9 speed cassette on an 8 speed setup - thats why its jumping around

 

[Peteaud]

you can't use a 9 speed cassette on an 8 speed setup - thats why its jumping around

What he said,.

you would need to fit a 9 speed shifter as well.

If you are staying with 8 speed shifters you need an 8 speed cassette.

Rear mech for 8 or 9 speed are all the same, it is the shifter that does the indexing for the gear.

 

[antnee]

I have changed Shifters which started out the change to the 9 speed saga in the first place as couldn't find any cheaper shifters than 9 speed ones on ebay.
as I wanted the paddle style shifters i.e not the ones where you have to click the small lever ( Shimano ST-2300 I think) to go to a smaller sprocket on the cassette as couldn't reach that small lever when on the drops.
Hence the new 9 speed Chain, 9 speed cassette and s/nd hand ST-5510 9 speed shifters
I mean it works but with these little annoying side effects though looking at 50 chainwheel that looks a bit worn as its done nearly 4000 miles this year (would this wear out this quick?) and lets face it the whole bike was only £300 new though after having done quite a few mods its more like £500 now.

Getting back to the Rear Derailleuer that has ample throw either way as you all know as its the H and L screws which control the travel stops and this part works fine, as does the 9 speed change in the 50 chainwheel position (ok youv'e got to be sensible about not cross chaining but thats common sense. the casssette works on all 9 sprockets when pedaling on the 39 chainring too ok it catches the FD slightley on the 39 chainwheel and 11 cassette sprocket but again as long as you don't cross chain your fine.

The main problem is the chain skip and if back pedaling more than half a revolution when on the 50 chainwheel and any cassette sprocket the chain comes off the chainwheel looking at the set up from the back it looks as though the jockey cage slopes inward toward the wheel. by about 2mm at the bottom. though never had any falls on to the ground that would have bent this. Is there any fixing thats adjustable between the bottom of the Derailleuer and the top of the jockey cage housing that might be loose; I can't see any fixing for this assembly at first glance!

Pehaps another visit to sheldon browns web site is in order. Meanwhile thanks for all your advice

 

[RecordAceFromNew]

There is a possibility that the mech hanger is not only bent from vertical, but also twisted in the vertical axis (which you might be able to spot if you look at the mech cage from above when the bike is upside down).

One easy way to checking hanger alignment is to use a rear wheel, but only if the wheel has a M10x1mm threaded axle (which e.g. most rear hubs made by Shimano have), because the hanger has the same thread. This is however not without some risk (of damaging/weakening the hanger).

What exactly happens when the chain skips when you are on 50x11?

 

[antnee]

Hi. When the chain skips I'm going down a slight slope most people would be happy to coast I'm trying to get just enough speed to go up the next slight incline without changing down, Its as though its jumping perhaps a couple of teeth on the 11 sprocket on the cassette I can't say I've seen it do it but thats what it feels like! What I will do is take a photo of the rear mech when the chain is on the 11 sprocket and 50 chainwheel and post it up on this page though have to wait till tomorrow now as too dark and wet out there at the moment .
Thanks
Mean while I will check out the mech hanger and see if theres a twist in it~

 

[Peteaud]

Can you post some pics?

 

[antnee]

Can you post some pics?

Here are some pics showing chain on 30 sprocket and 50 chainwheel for lenght and the second pic is of state of 50 chainwheel (which I wondered is this worn out yet) though wouldn't be cause of chain skip?
And lastly view of rear mech hanger when chain on 50 chainwheel and 11 sprocket I can see it looks to be lent toward the wheel but is this partly the angle of the picture as can't get directly behind as don't want to fiddle with mudgard