Can you mix and match sprockets on the rear cassette?

FrankGrimes · 12-07-2009 04:21PM #1

How much flexibility is there in terms of what sprockets you can put on the rear cassette?

I'll be buying a 12-28 10-speed SRAM cassette off TinyExplosions to replace the 11-25 I normally use to prepare for serious climbs. When 12 teeth is the smallest rear sprocket I've had before I've missed not having the 11 teeth sprocket mainly on descents or on rolling terrain.

So I'd like to mix and match the different rear sprockets so I could still have an 11-tooth sprocket at one end and the 28T at the other end - is that doable and does it pose any other risks (not worried about the larger intermediate gaps as long as it doesn't risk damaging the components)?

I can imagine that at some point in the Alps I'd gladly use a 30 tooth sprocket if it was there but from searching the web I haven't seen any of them - are they available and can you buy them as single sprockets?

I'd envisage going with a 30-28-27-25-X-X-X-X-X-11 setup just for the one day of doing La Marmotte route in September. I'd look to train on a normal 12-28 cassette but reckon if it's possible to have the above setup specifically targetted for serious climbs, why not go for it as if I don't need the 30/28tooth rings, great, but better to have them there in case.

blorg · 12-07-2009 04:26PM

You can't get bigger than 28 on a Shimano-compatible road cassette. If you want 30 you would have to get a MTB cassette and rear derailleur. These only come in 9 speed so I think you would have to change your STI lever as well.

ROK ON · 12-07-2009 04:34PM

Hi. BAck in May I got a few bad punctures on a back road in the Kerry mountains. Another cyclist stopped to help me (my pump was broken).

He had a Spesh Allez with a double. I thought his back cassette looked very large and I asked him what it was - he said 11/34 (eg MTB casette).

I asked was that compatible with his 105 groupset, and he said he just swapped out the cassette and been using it for a year.

Now he did admit that the gearing 'clicked and jumped' a lot - but that it got him over the climbs.

WOuldnt necessarily recommend it, but I sawthe guy climb up to help me, and then descend as I was finished repairing the bike.

blorg · 12-07-2009 04:35PM

Actually I found that Harris Cyclery do special 10 speed cassettes that go up to 32/34- you would have to change your rear derailleur to a 9 speed mountain bike one but your current 10 speed shifter should be OK (the indexing is in the shifter, not the derailleur.) A new RD would be easier and cheaper than changing your shifter.

psycholist · 12-07-2009 04:42PM

if you swap a 12 lockring the point where the teeth are machined down to allow for shifting would would mean the gap between the 11& 13 would be alot bigger than 12-13, sometimes this can throw your shifting off, not something you want to find out when your putting the power down doing 80kph on a descent and end up wiping yourself out, if you dont know whether itll work dont chance it

also a derailleur designed for a road double wont be able to take up the difference between an 11 and a 30...

you could just stick on a compact or a triple,which would involve you changing some of your mechs & shifters

real men only use 53/42 11-23's in the mountains :cool:

blorg · 12-07-2009 04:48PM

ROK ON wrote: »

He had a Spesh Allez with a double. I thought his back cassette looked very large and I asked him what it was - he said 11/34 (eg MTB casette).

I asked was that compatible with his 105 groupset, and he said he just swapped out the cassette and been using it for a year.

Now he did admit that the gearing 'clicked and jumped' a lot - but that it got him over the climbs.

There is a story of a spectator in some race giving his rear wheel to a rider that had crashed, I think it may have been Dave Zabriskie. Only problem was his wheel was 9 speed... It got him to the end of the stage. Indexing would be atrocious and would drive you mad.

There are some other options that let you use 10 speed shifters with a standard 9 speed MTB cassette though:

http://www.sheldonbrown.com/derailer-adjustment.html#alternate
http://jtekengineering.com/shiftmate.htm

blorg · 12-07-2009 04:52PM

@Frank- I am presuming here that you already have a compact chainset?

Lumen · 12-07-2009 04:56PM

You can buy an SRAM 11-28 cassette "off the shelf" (in Red at least), so maybe you could get an 11 tooth sprocket and swap it in to your 12-28. Might give some odd gaps though.

edit: FWIW, my Ultegra rear mech struggles a bit on the 27 tooth of my 12-27 cassette - I had to tweak the B adjuster to get it working nicely and the result is a bit of a compromise.

FrankGrimes · 12-07-2009 04:57PM

Thanks for the insight - so it seems there's not a quick and easy way to do it but it can be done with a bit of cost and effort if it comes to it, good to know.

Yeh, I have a compact at the moment and am hoping the 12-28T cassette will do the job and I won't need any more than that but I wanted to understand what the options are. I'll give it another 6 weeks and see how I'm fixed and make a call on whether or not I'll need an even bigger sprocket.

rughdh · 12-07-2009 05:11PM

IRD make 10 speed cassettes in 11-30, 11-32 and 11-34. Think they're all in chrome-plated steel, though, and a bit pricey.

SRAM are due to bring out a 10 speed MTB cassette soon. Not sure when, though, but it was supposed to be this summer, I think.[FONT=arial, helvetica][FONT=Arial, Helvetica, sans-serif][/FONT][/FONT]

blorg · 12-07-2009 05:40PM

Lumen wrote: »

edit: FWIW, my Ultegra rear mech struggles a bit on the 27 tooth of my 12-27 cassette - I had to tweak the B adjuster to get it working nicely and the result is a bit of a compromise.

I had a 27 on that bike (as I do on my current one) with absolutely no problems, no compromises! What problem are you having? 27 is even within Shimano spec for the derailleur and I know you can go beyond the spec.

You do need to change the B adjuster when changing between cassettes with different large sprockets (I have a 12-27 and an 11-23) but once done there should be no issues.

I haven't used one but 28 should work just as well.

TinyExplosions · 12-07-2009 06:17PM

FrankGrimes wrote: »

How much flexibility is there in terms of what sprockets you can put on the rear cassette?

I'll be buying a 12-28 10-speed SRAM cassette off TinyExplosions to replace the 11-25 I normally use to prepare for serious climbs. When 12 teeth is the smallest rear sprocket I've had before I've missed not having the 11 teeth sprocket mainly on descents or on rolling terrain.

I have a slight confession... due to a brain fart, you're actually getting an 11-28 off me

Should solve your problem just grand!

rughdh · 12-07-2009 06:20PM

blorg wrote: »

...
I haven't used one but 28 should work just as well.

I use a 28 with no problems. I would guess that the absolute limit is 30 (for a road derailleur), but will only work in certain cases.

Lumen · 12-07-2009 06:23PM

blorg wrote: »

I had a 27 on that bike (as I do on my current one) with absolutely no problems, no compromises! What problem are you having? 27 is even within Shimano spec for the derailleur and I know you can go beyond the spec.

No problem now that it's re-adjusted, but I noticed after a cassette upgrade that the sprocket was fouling the jockey wheel and jumping a bit.

The instructions I read for B adjustment gave a recommended clearance between jockey wheel and cassette, and when I had adjusted it to clear the 27 it was a bit far away from the 12 sprocket. Not sure what effect this has - less snappy shifting perhaps.

blorg · 12-07-2009 06:58PM

That's normal, I had to adjust the B screw to the limit when I went from my 23 to 27 myself.

FrankGrimes · 12-07-2009 09:47PM

TinyExplosions wrote: »

I have a slight confession... due to a brain fart, you're actually getting an 11-28 off me

Should solve your problem just grand!

Sweet, that'll solve the problem at the bottom end and hopefully the 28 is all I need at the top end. Hopefully get to meet up this week to get that off you.

FrankGrimes · 12-07-2009 10:06PM

rughdh wrote: »

IRD make 10 speed cassettes in 11-30, 11-32 and 11-34. Think they're all in chrome-plated steel, though, and a bit pricey.

Great tip, thanks. At $180 they aren't cheap but it'll be good to know during the training that there's some extra leeway available if needed as a fallback.

So this is purely hypothetical for the moment until I see if I need it, but would that just work straight away with my DuraAce rear derailleur and shifters, possibly with some adjustment of the B screw?

Is 11-30 the limit my derailleur/shifters could take or could it stretch to 11-32? Again that's hypothetical as the 11-32 has a big gap between the 32 sprocket and the 28T, whereas the 11-30 has 30,28,25... and hopefully it'd be mainly the 28 I'd use with 30 for backup.

Can you mix and match sprockets on the rear cassette?

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