Cycling UK Forum

Slightly convoluted and totally boring this one - but someone might know;

Are different models of Shimano cassette (of the same number of sprockets) compatible with each other? E.g. 11-speed Ultegra and XT?

The reason for asking is I have a Sram 11-speed cassette, 11-42; 11-13-15-17-19-22-25-28-32-36-42

BUT I never ever use the top two gears, partly cos I pedal quite fast but also cos I'm not a big macho dude. On the road I use mostly the 15 and 17 - so I've got too big a gap there plus two gears I carry around and never use.

So what I'd have ideally is 14-15-16-17-and the rest the same. Big gaps off road or up hills are fine, but when hunking along the flat into a headwind, the right gear really helps.

Sram don't make a 14T top sprocket, and as the top 2 are piggy-backed, that means using Shimano or something else, and they don't sell individual sprockets either, so the 3rd (16T) has to be an impostor as well.

So I changed the top three for Shimano sprockets, and the top three work beautifully but the change to the first Sram cos is a symphony of clattering and a very reluctant shift.

I tried making the top 4 Shimano - same problem between the two types. Wherever it crosses from Shimano to Sram, there's a cacophony of clacking and a slow shift or none at all.

So I'm wondering... if I made it ALL Shimano, with an MTB cassette, an XT or whatever, and used the same top three cogs off an Ultegra road 14-28, would the ramping be consistent or would I get the same problem?

I realize this is such a "niche" issue I'm well prepared for silence and tumbleweed!

Firstly there are small differences in the "ramps" and teeth shape between SRAM & Shimano sprockets - thus mixing doesn't make sense.

If you look at the "gear inches" calculators the differences at 1 tooth increments are very small and makes me think you're over-thinking it all and question whether even when riding into a headwind you'd notice any difference.

What's the bike - and what are the chainring(s) sizes?

Here is an old thread about mixing up Shimano sprockets from different cassettes. viewtopic.php?f=5&t=54328&hilit=nightmare&start=15
As I recall, the general experience is that the "join" between 2 cassettes can give a slightly clunky or hesitant shift, but I don't recall anybody reporting real problems. **
I use a 9 speed cassette made for junior "restricted gear" racing so it comes without the (to me) pointless small sprockets....but I have no idea if they are available now.....I splice it with an MTB cassette for the big sprockets.

** although this may be because the contributors started riding long before weird shaped sprocket teeth were a thing, and when every shift went in with a bang and it wouldn't shift at all unless you took the pressure off.....so whether or not the shift is acceptable may depend on your previous experience!

Take a look at Miche. You can build custom cassettes. I found the 14 to 29 10 speed very nice

robgul wrote: ↑28 Aug 2021, 5:28pm...If you look at the "gear inches" calculators the differences at 1 tooth increments are very small and makes me think you're over-thinking it all and question whether even when riding into a headwind you'd notice any difference...

Not true. It's the percentage change that matters. 1 tooth in 12 is as significant as 3 teeth in 32.

I did modify a 9 speed cassette to provide closer ratios and the results weren’t great. I used all Shimano cogs from two new 9 speed cassettes making sure they stayed in the same relative position in the set. The gear change varied from excellent to rubbish with the worst changes being consistent with the substituted cogs.
Spare single cogs - position specific - are available from certain retailers but I have never researched to see if there are multiple options (with differing ramps) for any one position.

If you don't need the smallest sprockets on the rear you could always fit a smaller chain ring. I use a 46t, which is one of the standards for Ultegra 6800, and has the advantage of reducing the drop from the big to the small ring. The only potential problem is getting the front mech low enough to be close to the chain ring. The gap on mine (due to having a braze on) is about 8mm - but with careful set up it works fine.
I have used both Shimano Road and MTB cassettes on my road bike and have also used Shram with no discernible difference.

gxaustin - I've had exactly that issue with double chainsets, filing the slot downwards to get the mech closer, and on one frame I even ground off the front mech braze-on altogether and used a clip mech! Here it's a single front ring, currently 42T, it's 110BCD so it could go down to 34T or 32T but the gaps at the back would still be big.

"I have used both Shimano Road and MTB cassettes on my road bike and have also used Shram with no discernible difference." - do you mean entire cassettes of one or the other, or mixing within a cassette?

Peetee - I've also modified plenty of 9-speed cassettes, lots of mixed & matched Shimanos and it's always worked perfectly, but they've always been from the same type - I've never mixed road and MTB.

freeflow - thanks for the Miche idea - I'll have a look.

531Colin - thanks for the link - I too started riding long before indexing, for years I was a skeptic, a luddite, a stick-in-the-mud... I used to modify Maillard freewheels for touring to get a 16T top!

I also don't get "the (to me) pointless small sprockets" - quite! For bikes to be commercially viable they have to cater for most people, and the common thing is that when you pedal slower you think you're making less effort - I've even had mates who don't ride much saying it's "easier" in higher gears... so just about all bikes are sold with stupid top gears that almost nobody could ever push, because "wow look in this gear I can do 50mph!!" (...for a worthless 5 seconds, if that!). At my very fittest ever I used to do 80-90 mile rides at averages over 20 and still rarely got into my then top gear of 100" on 52-14. But 11T and even now 10T seems to be standard. With a 42 front that's 113" - where are the incredible beefcakes that use that on an off-road bike?

robgul - two issues here:

Forgive the egg-sucking tutorial but I didn't get which bit of my post you didn't get: one is simple maths, the same difference is bigger relative to a smaller total; 1 to 2 is a big gap, 100 to 101 is a tiny gap, they're both a difference of 1. 10 to 11 is only a difference of 1 tooth but is a significant 10% difference, 40 to 41 is still a difference of 1 but is a 2.5% difference which as you say wouldn't be noticed - my top two are 11 and 13 - that's a big gap plus neither are useful gears. I did try to live with it, so it's not due to "over-thinking"!

The other thing is that on the road it rides like a road bike therefore I'm in the top few gears and like on a road bike, the gears need to be close together, whereas in the rough and tumble of off-road, speeds and conditions vary more so big gaps are fine. Hence wanting a few gears 1 tooth apart at the top, but leaving the rest the same.

"there are small differences in the "ramps" and teeth shape between SRAM & Shimano sprockets - thus mixing doesn't make sense.
"- yes... I said that in my original post. The question was whether you can mix within a brand.

531colin wrote: ↑28 Aug 2021, 5:41pm Here is an old thread about mixing up Shimano sprockets from different cassettes. viewtopic.php?f=5&t=54328&hilit=nightmare&start=15
As I recall, the general experience is that the "join" between 2 cassettes can give a slightly clunky or hesitant shift, but I don't recall anybody reporting real problems.

I run a 13-34 'special' made up from 2 Shimano cassettes, giving a 1 step top 3 gears. The 'join' is noticeable, but OK (using indexed bar end shifter) - but then my first bike had a 5 speed freewheel...

Shimano only use 16t sprockets in their closer ratio 11 speed cassettes. Miche do not offer a bigger largest sprocket than 34t in 11 speed.

To get the gears you are seeking and have smooth shifts, you probably need a super compact double chainset.

For example, a comparison of your mooted ideal gearing with a super compact double and close ratio cassette:

http://www.gear-calculator.com/?GR=DERS ... 5&UF2=2170

Having those most used gears closer to the middle of the cassette also gives better chainline.

"I have used both Shimano Road and MTB cassettes on my road bike and have also used Shram with no discernible difference." - do you mean entire cassettes of one or the other, or mixing within a cassette?

I've never mixed any cassette. I must have misread the post somewhere.

If you want a set of close ratio 11-speed cogs with a smallest of 14t, look for a cassette intended for junior racing, where there is a limit on the top gear allowed - I think the limit is something like 52x14. Shimano, for example, make a 14-28 11-speed cassette: https://bike.shimano.com/en-EU/product/ ... R8000.html. The advantage of using the small cog from one of those cassettes is that the 14t cog has serrations on its face to engage the lockring, whereas if you use a 14t cog not intended as an outer, it will have a smooth face.

You should be able to combine the smallest sprockets off one of those with the other sprockets off an MTB cassette to get what you want. For example, the Ultegra junior cassette is 14-15-16-17-18-19-20-21-23-25-28; a Deore 11-42 cassette is 11-13-15-17-19-21-24-28-32-37-42. You could combine those two to get 14-15-16-17-19-21-24-28-32-37-42.

Thanks everyone for all the replies! Apologies for the overly long original post, probably why the actual question got buried! But I'll try mixing Ultegra with XT as NickJP suggests and see if the ramping works between the two.

The Ultegra 14-28 is what I've already been using the top 3 cogs from, frustratingly most shifts to the first Sram cog are perfect but every few goes it just clatters and refuses to shift - so I'm giving up and I've put the original Sram cassette back together, but will try the XT (when it arrives in the post...).

I also thought of grinding a "shift gate" into the last Shimano cog, as I can see the chain not lifting off at the right time for the first Sram cog to catch it... but that's getting really fiddly! I'll only try that as a last resort.

OK, if anyone's still here - this is the (nail-biting!) conclusion:

There's NO compatibility even within Shimano, the cutouts in the cogs are in different places and the exact same mismatch between Ultegra and XT occurs as between Ultegra and Sram. Lots of clatter and no shift, if anything slightly worse than Shimano/Sram which worked about 3/4 of the time.

SO: I identified which tooth the chain was slipping on, i.e. slipping back down onto the cog I'm trying to shift OFF, and ground the top of the tooth off at an angle to mimic the equivalent teeth on other cogs, and also ground flat across the top of the tooth on the next cog that's picking up the chain, again with an angle to mimic the equivalent on other cogs.

This is without trying to replicate the ramps cut into the sides of the sprockets - I only ground the tops of the teeth.

Result: I've just been round the block on it and it's a PERFECTLY smooth shift from Ultegra to XT - the smooooothest shift in the history of shifting. I'll go on a proper ride tomorrow so if there are any surprises I'll be back to comment, but so far - shifted about 20 times and not a single bit of clatter.

So it CAN be done! But you need an angle grinder or a very sharp file, and a bit of patience identifying which teeth are the culprits. And I don't know if it would work as spectacularly well between Ultegra and Sram.

That's amazing work - well done, a well-deserved success! I would have bet on that failing, and a pile of useless metal filings

Out of interest, did you try doing a two-down-one-up shift to get from 11-to-13T [i.e. across two larger cogs, then back one]? Irritating, I know, but I'm just curious, as I had no idea that the ramps etc made such a huge differnece.

I realise your lever may not allow this - I don't own fancy modern stuff, sorry!