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Old 12-30-10, 10:32 PM   #1
5shot
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FSA chainring not compatible with SRAM Red crankset...

I am waiting for my new cyclocross frameset to arrive. The frameset requires a BB30 crank and bottom braket so I purchased a compact SRAM Red BB30 crankset that comes with 50/34 chainrings. Also purchased 46 and 36 toothed FSA chainrings because that's the combination I use for 'cross and SRAM doesn't make this combination (no 110 BCD 46t SRAM chainring exists to my knowledge).

This evening I removed the Red chainrings and was going to install the FSA chainrings but the 46t FSA chainring would not fit. Upon inspection it was obvious that the pin on the 46t chainring that sticks out towards the crank arm and that, as far as I've always been told, you are supposed to align with the crank arm to prevent the chain from slipping between the large chainring and the crank arm, was hitting the crank arm and preventing the chainring from seating properly on the spider. I then looked at the SRAM 50t chainring and saw that it does not have such a pin.

So, should I simply grind the pin down until it no longer touches the crank arm? Should I rotate the 46t chainring one position so that the pin is no longer under the crank arm? Should I look for a 46t chainring that does not have a pin?

Thanks for any advice.
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Old 12-30-10, 10:50 PM   #2
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Don't over think this.

The pin is there to do one simple job. Close the gap so a chain can't slip in. If it's too long, grind or file it down, so it still does the job without touching the arm.

Why would you even consider mounting the ring with the pin hanging out in space to snag your socks?
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Old 12-30-10, 11:03 PM   #3
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Don't over think this.

Why would you even consider mounting the ring with the pin hanging out in space to snag your socks?
I was brain storming possible solutions. I never stated that rotating the chainring one position was a great idea, just one possible solution.
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Old 12-30-10, 11:12 PM   #4
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I was brain storming possible solutions. ...
Not meaning to pick on you, but that's my point. Simple problems call for simple solutions. Unless you had an objection to shortening the pin - maybe no file handy - there was nothing to brainstorm.
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Old 12-30-10, 11:18 PM   #5
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if as long as it doesn't distort the chainring, pin touching arm lightly should do no harm.

perhaps as they consider the 50 a road chainring

they thought pin didn't matter.

you could always kludge a poprivet to make a pin , or drill and tap a small screw ..

NB with aluminum a file is better than a grinder

[aluminum in grinding wheels is not good]

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Old 12-30-10, 11:24 PM   #6
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I would just file down the minimum necessary so that pin so it fits behind the crankarm. I'm curiours to know what, if any shift perforamnce degradation there would be with using

a) fsa chainrings with a sram chain
b) fsa chainrings on a sram crank spider
c) nonstandard 46/36, with sram front derailleurs
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Old 12-31-10, 01:23 PM   #7
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I would just file down the minimum necessary so that pin so it fits behind the crankarm. I'm curiours to know what, if any shift perforamnce degradation there would be with using

a) fsa chainrings with a sram chain
b) fsa chainrings on a sram crank spider
c) nonstandard 46/36, with sram front derailleurs
For what it's worth, on my current 'cross bike I am running Force brake/shift levers, Force FD, Force RD and SRAM PC 1091R chain. The crankset is FSA Energy compact with FSA 46/36 chainrings. This set up functions flawlessly.
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Old 12-31-10, 01:27 PM   #8
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The pin on the FSA 46t ring does more than just touch the crank arm. The pin/crank arm interface completely prevents mounting the chainring. Also, I need to correct my earlier statement. The 50t SRAM Red chainring does indeed have a pin that aligns under the crankarm. The reason the FSA pin hits the crank arm is that the crank arm bends in as it approaches the spider and this decreases the clearance between chainring and crank arm.
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Old 01-01-11, 07:23 AM   #9
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No-brainer: file if ally, grind if steel.
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