Campagnolo 12 speed cassette compatibility

Discuss light weight issues concerning road bikes & parts.
fehguy
Posts: 7
Joined: Fri Aug 30, 2019 4:32 am

by fehguy

Hi folks,
I scoured the Internet looking for information on this but came up empty. I'm a long-time Campagnolo fan (been riding it ever since I could afford it) and would like to continue being so. Sadly, compatibility with Campagnolo has been an after-thought for most 3rd party parts providers. I also am a #1 Chris King fan and would like to keep riding their hubs. The challenge I faced is that newer, 142x10mm through axles are no longer available for Campagnolo cassette free hub bodies. So lies the challenge...

SRAM makes nice parts. They don't have the cache or soul of Campagnolo but it's hard to argue against how revolutionary their 12-speed AXS group is. My question was, could a 12-speed SRAM AXS cassette work with a Campagnolo 12-speed EPS Super Record group?

I spent way too much time searching around for an answer to this. Possibly because the Campy loyalists would never run a SRAM cassette, or possibly because people just don't mix-and-match like they used to. The only way to get a clear answer was to measure.

I got a hold of a SRAM 10-28 XDR cassette and a Campagnolo 11-32 Super Record cassette. I went into this very skeptical about them working together, mostly because you'll read everywhere that "Campagnolo squeezed 12 gears into the space of 11 for hub compatibility". That sounded a lot like a much more narrow spacing than any of the other 12 speed groups.

Well, taking a look at a super record cassette in person, it's a bunch of hooey. The largest cog hangs over past the end of the cassette by 0.070"! They don't fit in the same space, the 12 speed Campy just pushes the last cog over the spokes a bit.
IMG_1085.jpg
There's a nice "chain catcher" on the largest cog, which can help keep the chain from wedging into the spokes on an overshift. The rest of the cassette is evolutionary Campagnolo. Two groups of 3 cogs with the same size spacer between the loose gears. It's very nicely made and definitely is a more thoughtful design than the older 11 speed varieties.
IMG_1088.jpg
The SRAM is a leap forward. I do believe the XDR cassette body is a better design, and it allows for a 10-tooth gear. The attachment mechanism is smart--the cassette body transfers load throughout the whole two-piece unit, keeping the gears from digging into the sides of the aluminum freehub body. It may not be as beautifully machined, but it is a (sadly to me) better design. I really wish the whole industry would embrace the XDR free hub body as a standard.
IMG_1089.jpg
Now for measurements... I took some calipers and measured (in inches, sorry!) the cassette total width, spacing, overhang, and cog width.

The Campagnolo measures 1.610" from outside-to-outside of the cogs. Each cog is about 0.057" thick with 0.080" of spacing between them (the "about" is because of the machined profile). The 11-tooth cog--like the 11 speed versions--will "fit into" the 12-tooth cog slightly.

The SRAM measures 1.631" from outside-to-outside, so it is a hair wider than the Campagnolo. The cogs are slightly wider at 0.070 for the 28-tooth aluminum gear to 0.062 for the steel ones. The spacing between cogs is also uniform.
IMG_1087.jpg
Conclusion? We're looking at a 0.021" delta over the width of 12 cogs, or about 0.5mm. I think this is within the tolerance of bicycle components and that the standard EPS adjustments will make it work. Parts are on order and I'll report back.
IMG_1086.jpg
It's worth noting that the difference in total width between the two is much less than the difference in total width between Campagnolo 11 speed and Shimano 11 speed.

Photos below, I hope this is helpful to someone!

octav
Posts: 200
Joined: Thu Aug 27, 2009 12:40 pm
Location: Bucharest

by octav

Nice, keep us posted how it works. It's really intersting if I could run a 12 speed Sram Cassette on Campy SR12.

by Weenie


User avatar
Miller
Posts: 1638
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

In the US is engineering work really done using inches for measurement? That's mind-boggling to me.

Nice description of the cassettes, btw. About the design, bear in mind the Campag cassette carrier uses a deep spline so sprockets digging into the body has never been a problem.

XCProMD
Posts: 811
Joined: Sat Jan 26, 2008 10:25 am
Location: Cantabria

by XCProMD

What an excellent post, thank you.

I agree that XD-r is the best current solution, and it would cover every application as it works with sprockets as small as 10 T.

Campagnolo’s merit on the other hand has been being able to keep the same sprocket carrier since 1996 and make it compatible from 9 to 12 cogs. It’s going to be difficult for them to get a 10s but it seems they have an idea on how to make it keeping the corsos compatibility in case they would really need to have “super compact” drivetrains.

And this points again to the elephant in the room. Shimano’s Microspline exists only because the Japanese need and can impose a closed ecosystem around their product. There was already a working solution for a 12s XTR cassette carrier and a future DA, but they simply don’t accept standards not stabilised by themselves. Pity the poor consumer.


Skickat från min iPhone med Tapatalk

User avatar
pdlpsher1
Posts: 2424
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

0.53mm is a big difference. I don't think it'll work. But you can try and report back your findings.

morrisond
Posts: 962
Joined: Thu Mar 25, 2004 8:34 pm

by morrisond

fehguy wrote:
Tue Sep 03, 2019 2:03 am
Hi folks,
I scoured the Internet looking for information on this but came up empty. I'm a long-time Campagnolo fan (been riding it ever since I could afford it) and would like to continue being so. Sadly, compatibility with Campagnolo has been an after-thought for most 3rd party parts providers. I also am a #1 Chris King fan and would like to keep riding their hubs. The challenge I faced is that newer, 142x10mm through axles are no longer available for Campagnolo cassette free hub bodies. So lies the challenge...

SRAM makes nice parts. They don't have the cache or soul of Campagnolo but it's hard to argue against how revolutionary their 12-speed AXS group is. My question was, could a 12-speed SRAM AXS cassette work with a Campagnolo 12-speed EPS Super Record group?

I spent way too much time searching around for an answer to this. Possibly because the Campy loyalists would never run a SRAM cassette, or possibly because people just don't mix-and-match like they used to. The only way to get a clear answer was to measure.

I got a hold of a SRAM 10-28 XDR cassette and a Campagnolo 11-32 Super Record cassette. I went into this very skeptical about them working together, mostly because you'll read everywhere that "Campagnolo squeezed 12 gears into the space of 11 for hub compatibility". That sounded a lot like a much more narrow spacing than any of the other 12 speed groups.

Well, taking a look at a super record cassette in person, it's a bunch of hooey. The largest cog hangs over past the end of the cassette by 0.070"! They don't fit in the same space, the 12 speed Campy just pushes the last cog over the spokes a bit.

IMG_1085.jpg

There's a nice "chain catcher" on the largest cog, which can help keep the chain from wedging into the spokes on an overshift. The rest of the cassette is evolutionary Campagnolo. Two groups of 3 cogs with the same size spacer between the loose gears. It's very nicely made and definitely is a more thoughtful design than the older 11 speed varieties.

IMG_1088.jpg

The SRAM is a leap forward. I do believe the XDR cassette body is a better design, and it allows for a 10-tooth gear. The attachment mechanism is smart--the cassette body transfers load throughout the whole two-piece unit, keeping the gears from digging into the sides of the aluminum freehub body. It may not be as beautifully machined, but it is a (sadly to me) better design. I really wish the whole industry would embrace the XDR free hub body as a standard.

IMG_1089.jpg

Now for measurements... I took some calipers and measured (in inches, sorry!) the cassette total width, spacing, overhang, and cog width.

The Campagnolo measures 1.610" from outside-to-outside of the cogs. Each cog is about 0.057" thick with 0.080" of spacing between them (the "about" is because of the machined profile). The 11-tooth cog--like the 11 speed versions--will "fit into" the 12-tooth cog slightly.

The SRAM measures 1.631" from outside-to-outside, so it is a hair wider than the Campagnolo. The cogs are slightly wider at 0.070 for the 28-tooth aluminum gear to 0.062 for the steel ones. The spacing between cogs is also uniform.

IMG_1089.jpg

Conclusion? We're looking at a 0.021" delta over the width of 12 cogs, or about 0.5mm. I think this is within the tolerance of bicycle components and that the standard EPS adjustments will make it work. Parts are on order and I'll report back.

IMG_1086.jpg

It's worth noting that the difference in total width between the two is much less than the difference in total width between Campagnolo 11 speed and Shimano 11 speed.

Photos below, I hope this is helpful to someone!
What Hub/Frame are you trying to make work with Chris King and an 142x10 Thru Axle and Campy cassette? A Storck Disc Brake frame?

I9 Makes hubs that will work with that Spec and Campy or I believe DT swiss does as well.

DaveS
Posts: 2630
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

The OP came up with the same sprocket dimensions for Campy 12 that I did. Adding the sprocket thickness and space between gives you the center to center spacing of .137 inch or 3.48mm. Having the same two dimensions for the SRAM cassette would be valuable.

I've never read up on the exact difference in sprocket spacing between the brands with 11 speed, but I've read many reports that people think that all brands are close enough to be used interchangeably. I do know that Campy 11 spacing is a little larger. If the difference in the 12 speed cassettes is smaller, it would support the idea that the two are interchangeable. If the difference in spacing is only about .002 inch or .05mm, careful centering of the RD travel and adjustment of the limit screws should make it work.

As for Campy's 12 speed cassette design being hooey, I've never inspected a Record or SR cassette, but the Chorus 11-34 cassettes that I have are pretty slick. The last 3 sprockets are joined with no rivets or fasteners of any sort and they fit onto the same hubs that accept 9-11 speed cassettes. I can't complain about that. If you want to use a SRAM 12 cassette on a Campy wheel, all it takes is a Fulcrum XDR driver, that costs about 110 USD.

The SRAM chain is narrower, but it will work just fine with Campy cogs and chain rings, despite the .006 inch large diameter rollers on the SRAM chain. The SRAM chain follows the #40 drive chain design, while all other bike chains use the #41 drive chain specification, which are English standards for 1/2 inch pitch chains. You can convert anything to metric with multiplication by 25.4.

I've been using a SRAM Force chain on one of my Campy 12 bikes for several weeks with no problems. I've made several close visual inspections of the chainrings and sprockets and not seen any evidence of excessive wear and certainly no deformation of an aluminum chainring that one poster suggested. The little ring has the greater chain tension and I have a 32T little ring. It's the one to keep an eye on. I have two 48/32 crank and both were brand new a few weeks ago. I put the force chain on one crank from day one.
Last edited by DaveS on Wed Sep 04, 2019 11:18 pm, edited 1 time in total.

fehguy
Posts: 7
Joined: Fri Aug 30, 2019 4:32 am

by fehguy

@miller yes, English measurements in the states, and for traditional machining, it'll probably never change...

I do need to make sure my comment wasn't out of context. I think the campy 12 speed cassette is really nice, what was "hooey" is that I've been reading how Campy just jammed 12 cogs in the same space as 11. They did indeed make them closer together, but hung the largest cog off towards the center of the wheel. So I expected the cogs to be _very_ close together but to my delight, they are about the same as SRAM.

@DaveS I'll measure the SRAM center-to-center tonight and report back what I get.

@MorrisonD I'm building up a Mosaic RT-1d I know there are easier setups but I was the original engineer on the King Hubs, so I have a strange loyalty to use them :lol:

Fingers are crossed that it all works. If not, this was a very expensive experiment...

mrfish
Posts: 1666
Joined: Wed Mar 28, 2007 12:49 pm
Location: Near Horgen, Switzerland

by mrfish

Good to know. Similar to my experience with 10 and 11 speed Shimagnolo.

If I want to Zwift this winter on Campy 12 bike and Shimano 11 bikes on a wheel-off trainer, is there a solution which allows using a Shimano cassette body and shaved down cassette spacers for Campay 12 so I only have to change the cassette? Or do some turbos work like DT hubs so that I could buy two cassette bodies and swap body and cassette by simply pulling them out?

User avatar
pdlpsher1
Posts: 2424
Joined: Thu Jul 19, 2012 6:09 pm
Location: CO

by pdlpsher1

Obviously the Sram cassettes all start wih the 10-tooth cog. Will the Campy RD shift reliably from 11 to 10 and back to 11? Also the XDR conversion kit for King hubs are very expensive, since the kit basically replaces half of the parts on the King hub. The price for the kit is $309. Also a Sram cassette is $350.

Image

fehguy
Posts: 7
Joined: Fri Aug 30, 2019 4:32 am

by fehguy

@pdlpsher1 we're going to find out! I'm going to do some adjustment hacking with the EPS when I have it installed--I'll report back here what I find. But specifically, I'm looking to see how the stop adjustments affect the travel between gears. The silly thing about electronic shifting compatability is that any of the shifter/derailleur combos should theoretically be able to shift between "any" cassette spacing, since the cog locations are really just handled in software. So if that's the case, will adjusting the stops on the Campy EPS on the high and low side affect the travel between gears? I don't know! But if I were designing the software, I'd probably build that in.

Should have the parts this weekend.

voidjava
Posts: 4
Joined: Fri Aug 28, 2015 7:22 pm
Location: Greece, Xanthi

by voidjava

I am planning to play somewise like you. I want to go for 12s campagnolo (mechanical) shifters and derailleurs with 10-33 sram cassette. I'm still studying it

bm0p700f
in the industry
Posts: 4963
Joined: Sat May 12, 2012 7:25 pm
Location: Glermsford, Suffolk U.K
Contact:

by bm0p700f

0.5 mm over 12 sprocket is half all per sprocket. I doubt people tune there drive trains to within 0.04mm of the central tre of the sprocket.

Campag eps rd are not.likely to like the 10t sprocket much.

The issue will be I the low and high sprocket. Eps knows where they should be. So expect the chain in those two cogs to be a bit more noisy than normal. Otherwise it should function reasonably well if the rd allow the 1pt sprocket to work.

DaveS
Posts: 2630
Joined: Fri Mar 24, 2006 1:26 pm

by DaveS

As for the RD, I would not expect a problem. All it does is rest on the limit screw in the top gear and move the cage over about 3.48mm to make each shift, just like a cable would.

gwerziou
Posts: 56
Joined: Wed Feb 20, 2019 7:25 pm
Location: Ballard, WA

by gwerziou

This is a great thread. Were there ever any conclusions on how it worked out?

by Weenie


Post Reply
  • Similar Topics
    Replies
    Views
    Last post