Campy Crank with SRAM Apex 1x (chainline OK?)

[robertbb]

Hey all,

I've got a Campagnolo Athena UT 5 arm crankset, which could be repurposed for 1x usage with a NW chainring (as some have done on this forum).

My intention is to run SRAM Apex 1x (with flat bar trigger shifter) - would this set-up would be sub-optimal compared with a SRAM Apex 1x crank, or would it be OK?

I like UT cranks, and run them on two other bikes. I have all the tools to work with them, replace bearings etc, so if performance/reliability won't suffer I'd happily mix and match.

[ultraman6970]

If you are going 1x i do not see why it should not work.

2x I would not know because the darn FDs other brands are a problem with anything that is campagnolo sometimes. But 1x I do not see the problem.

[oldpotatoe]

Originally Posted by robertbb

Hey all,

I've got a Campagnolo Athena UT 5 arm crankset, which could be repurposed for 1x usage with a NW chainring (as some have done on this forum).

My intention is to run SRAM Apex 1x (with flat bar trigger shifter) - would this set-up would be sub-optimal compared with a SRAM Apex 1x crank, or would it be OK?

I like UT cranks, and run them on two other bikes. I have all the tools to work with them, replace bearings etc, so if performance/reliability won't suffer I'd happily mix and match.

It will work just fine...shifters/der, etc, doesn't really care about the crank..

[robertbb]

Thanks all - will be sticking with Athena Cranks (135mm BCD) together with the following 1x J&L NW chainring:

https://www.ebay.com/itm/J-L-Narrow-...-/352323369099

[dookie]

I've been using a Centaur square taper with an otherwise SRAM 2x drivetrain for many miles...works great.

[Mark McM]

There's two questions here: Will it work; and will it be ideal.

One of the issues when using a crank mis-matched with the rest of the drivetrain is chainline. According to the SRAM 2019 Frame Fit Specifications, the Apex 1 crank has a chainline of 43.7 mm (i.e., the chainring is offset 43.7m from the neutral plane of the frame). According to the Campagnolo Ultra-Torque Specifications, Ultra torque 135mm BCD double cranks have a chainline of 43.5 mm (i.e., the centerline between the two chainrings is offset 43.5m from the neutral plane of the frame).

As the spacing between chainrings on a double crank is about 8mm, then the chainline at the inner chainring position of a Ultra-Torque is about 39.5mmm, and the chainline at the outer chainring position is about 47.5mm, and each position would be about 4mm off from the SRAM Apex 1 crank. In other words, neither the inner nor outer chainring positions of the Ultra-Torque crank would be ideal for a 1x system, and would result in extreme cross-chaining at one end or the other of the cassette (depending on which chainring position was used).

[thermalattorney]

Originally Posted by robertbb

Thanks all - will be sticking with Athena Cranks (135mm BCD) together with the following 1x J&L NW chainring:

https://www.ebay.com/itm/J-L-Narrow-...-/352323369099

Good choice, I've used the 110bcd version of that ring for over a year and it's a solid NW ring, no issues.

[chiasticon]

fwiw, I ran a Wolftooth NW ring on a Quarq Elsa four-bolt (i.e. made for 6800/9000 level Shimano) crank all of last CX season. with a Rival rear shifter and derailleur. no issues.

not the same setup as you, but the point is: the shifter/der/chain/ring basically don't care about the crank.

[oldpotatoe]

Originally Posted by Mark McM

There's two questions here: Will it work; and will it be ideal.

One of the issues when using a crank mis-matched with the rest of the drivetrain is chainline. According to the SRAM 2019 Frame Fit Specifications, the Apex 1 crank has a chainline of 43.7 mm (i.e., the chainring is offset 43.7m from the neutral plane of the frame). According to the Campagnolo Ultra-Torque Specifications, Ultra torque 135mm BCD double cranks have a chainline of 43.5 mm (i.e., the centerline between the two chainrings is offset 43.5m from the neutral plane of the frame).

As the spacing between chainrings on a double crank is about 8mm, then the chainline at the inner chainring position of a Ultra-Torque is about 39.5mmm, and the chainline at the outer chainring position is about 47.5mm, and each position would be about 4mm off from the SRAM Apex 1 crank. In other words, neither the inner nor outer chainring positions of the Ultra-Torque crank would be ideal for a 1x system, and would result in extreme cross-chaining at one end or the other of the cassette (depending on which chainring position was used).

Not up on my geometry but don't thing those 4mm will result in 'extreme cross chaining'...just my opinion...as others have mentioned, a non 1by sram crank has worked fine for others...

[Mark McM]

Originally Posted by oldpotatoe

Not up on my geometry but don't thing those 4mm will result in 'extreme cross chaining'...just my opinion...as others have mentioned, a non 1by sram crank has worked fine for others...

I didn't say it wouldn't work, I said it wouldn't be ideal. With a 2x drivetrain, I've had instances where the chain would be pulled off the outer chainring when using the largest sprocket in the rear. Using a narrow-wide chainring should solve this problem, but it will still result in increased friction and wear.

[oldpotatoe]

Originally Posted by Mark McM

I didn't say it wouldn't work, I said it wouldn't be ideal. With a 2x drivetrain, I've had instances where the chain would be pulled off the outer chainring when using the largest sprocket in the rear. Using a narrow-wide chainring should solve this problem, but it will still result in increased friction and wear.

No, you said it would result in 'extreme cross chaining'...and I mentioned, it would be 4mm(.157480 inch) from being centered on a line between the middle of the cogset and the chainring...
ANY 1by system, even when properly centered, when operating at the extremes of the cogset, will result in 'increased friction and wear', when compared to a 2by system where you use the small ring for bigger cogs(lower gears) and big ring for smaller cogs(higher gears). But that difference, like that .157 inch, is kinda lost in the noise.

The gent wants to use a double crank for 1by...sure, use it..

[Mark McM]

Originally Posted by oldpotatoe

No, you said it would result in 'extreme cross chaining'...and I mentioned, it would be 4mm(.157480 inch) from being centered on a line between the middle of the cogset and the chainring...
ANY 1by system, even when properly centered, when operating at the extremes of the cogset, will result in 'increased friction and wear', when compared to a 2by system where you use the small ring for bigger cogs(lower gears) and big ring for smaller cogs(higher gears). But that difference, like that .157 inch, is kinda lost in the noise.

The gent wants to use a double crank for 1by...sure, use it..

So then, you agree with me. Using a double crank will result in even more cross-chaining than with a 1x crank, with its extra friction, wear (and possiblity of chain breakage). In any case, the OP's question was about chainline, which I answered.

I'm not sure the different gets lost in the noise, though. In this Velonews test published a few months ago, they compared an SRAM 1x drivetrain with a Shimano 2x drivetrain. For this test, they aligned the chainline of the 1x chainring with the same offset as the outer chainring of the 2x drivetrain (similar to what the OP is intending to do). This test found that the relative frictional losses increased dramatically as the cross-chaining increased with the 1x drivetrain, with the losses in the biggest sprocket on the 1x drivetrain being about 30% greater than with inner chainring on the 2x drivetrain - those losses primarily due to the extreme cross-chaining. I'm not sure I'd call that simply "noise".

[oldpotatoe]

and possiblity of chain breakage

Yawn....your propensity for ‘big words’ and doom and gloom is interesting. ‘Extreme’, ‘increased dramatically’. Don’t think that .157 inch is gonna result in a broken chain. Of course alloy chainring boots are ‘extremely lighter’ than steel
Too...