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SRAM AXS upgrade

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SRAM AXS upgrade

Old 10-25-19, 04:34 PM
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colombo357
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SRAM AXS upgrade

Time to upgrade our Cannondale Road Tandem drivetrain.

Currently have triple chaingrings, mechanical Ultegra, and Avid BB7. I'd like to upgrade to full SRAM AXS Force with double rings and hydraulic discs.

Anyone done this yet? Did you swap out both cranksets?
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Old 10-25-19, 09:43 PM
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OneIsAllYouNeed
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The shifters, derailleurs, and brakes are straightforward. Stoker cranks are the real challenge.

2x12 SRAM AXS requires the AXS chain. The only chainrings compatible with that chain are the Force or Red AXS chainrings in 46/33, 48/35, and 50/37 combinations. Those chainrings are only compatible with Force, Red, and Quarq cranks that have the 8-bolt pattern.

Accepting those limitations, you can piece together a tandem crankset. For a right side sync chain, you’d need an extra 107bcd inner ring, longer chainring bolts, and some spacers. Your frame probably doesn’t have room for that with the stock spindle lengths on those cranksets. I’ve had success on 11-speed Force cranks, but the left AXS crankarms are permanently bonded to the spindle.

Using a conventional left side sync chain, you’d need a spindle and right crankarms that fit the DUB spindle. This has strong potential to work.
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Old 10-25-19, 09:54 PM
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Looks like there may be some easier options for cranks. Carbon-Ti now has AXS chainrings for 110bcd 5-bolt and (Shimano asymmetric) 4-bolt. That opens up a lot more crank choices. Rotor is supposedly making some AXS 2x chainrings, too.
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Old 10-28-19, 04:41 PM
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Thank you for pointing me in the right direction! Probably saved me days of scouring!
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Old 11-19-19, 09:07 AM
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I'm in the process of upgrading to the Force AXS 12 speed now on my 2012 Cannondale Road 2 using a kit from House of Tandems in TX. Just started the process this week and right now I'm battling one issue.

The kit comes with a 52/34 set of rings for the front to put on the existing Gossamer crankset. I've found that the 52 conflicts with the chainstay. The stock MexaExo BB on the bike is the 7000TD, which has only 2 spacers. The bike came with those spacers on each side of the BB. One solution was to move the spacers to the drive side but that left the left side crank very close to the stay on the left side. So, my next step is to move back to the spacers on each side and try a 50 tooth "big" ring on the front. HoT and I are confident that will work and will give me plenty of high end for the type of riding we do. Cassette is a custom 11-42 12-speed that HoT puts together.

After that, it will be on to the derailleurs and chain which I hope will go smooth...
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Old 11-19-19, 01:43 PM
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Originally Posted by tandemfor2
I'm in the process of upgrading to the Force AXS 12 speed now on my 2012 Cannondale Road 2 using a kit from House of Tandems in TX. Just started the process this week and right now I'm battling one issue.

The kit comes with a 52/34 set of rings for the front to put on the existing Gossamer crankset. I've found that the 52 conflicts with the chainstay. The stock MexaExo BB on the bike is the 7000TD, which has only 2 spacers. The bike came with those spacers on each side of the BB. One solution was to move the spacers to the drive side but that left the left side crank very close to the stay on the left side. So, my next step is to move back to the spacers on each side and try a 50 tooth "big" ring on the front. HoT and I are confident that will work and will give me plenty of high end for the type of riding we do. Cassette is a custom 11-42 12-speed that HoT puts together.

After that, it will be on to the derailleurs and chain which I hope will go smooth...
Yes, as you found out, the Cannondale has some fat chainstays which leave little room for chainring clearance.

Depending on how much clearance was needed for your 52T ring, I might have tried splitting the difference of one of the spacers by using alternate BB spacers which total up to the same width, then do 1/2 on timing side and 1 1/2 on drive side.

Most likely you will find the 50T x 11 plenty big enough. We are a fast, non-racing team and do just fine with a 48x11 top gear.
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Old 11-19-19, 02:59 PM
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The AXS 12 chain compatibility problem has been exaggerated. I've used it on my Campy 12 drive train and even gave it a brief try on an 11 speed Campy crank. Others have used a Campy 12 chain with an AXS cassette and had no problem.

Last edited by DaveSSS; 11-19-19 at 03:18 PM.
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Old 11-19-19, 03:05 PM
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Old 12-16-19, 06:11 PM
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Just wanted to pop in and give an update. The Tandem is all built up and working great! Just did a little test riding around the block because the weather is a bit cold for my stoker.

Settled on the 48x34 up front and 42x11 in the back. Sized the chain for the big-big and get the full range on the 48, and a few of the low gears on the 34, but that is all that's needed.
It was a lot easier to tweak the front derailleur positioning with the 48x34. Shifting is smooth as silk...can't wait to spend next season with it. So a summary:
1) 42x11 custom casette
2) 48x34 chainrings
3) Force AXS 12 speed, rear derailleur on a Road Link to handle the big cogs

Let me know if you have any questions.
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Old 12-16-19, 08:54 PM
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Why did you end up with the 48T? Did the 50T not work?
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Old 12-19-19, 10:39 AM
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The 50 was still just a little too tight for my taste with regards to its spacing from the frame. It probably would have been OK. The 48T has better clearance and I expect we'll gravitate to the lower gears rather than the higher ones. I don't know if there would have been any issues with the front derailleur with the 50T, but as it is, it has to be mounted slightly higher on the seat tube than the norm to prevent rubbing on some of the features prominent on the cage.
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