Do you think this none drive side crankarm will come off ?

Discuss light weight issues concerning road bikes & parts.
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Joined: Sat Jun 13, 2009 4:02 am
Location: NoVA/DC

by thisisatest

shimano dishes their outer ring, the teeth of the outer ring is farther away from the teeth of the inner ring. in between the rings is the large chainring's composite ramps. FSA has rings that are similar, they are listed as DA79 or more currently N10 (as in DuraAce 7900 and NEW 10speed). Sram Exogram rings exploit this as well.
the benefits are greater small/small cross chaining capability, less chance of inside chain drop, no tendency for the chain to "float" on the inner ring when downshifting.
spacers may work, they may also cause the chain to float on the inner ring when downshifting. it's most apt to happen when the chain is in the 5th, 6th,7th cogs.

Posts: 35
Joined: Fri Feb 03, 2012 9:10 am

by coolmingli

I made some phone calls to Praxis, Rotor, Shimano, here is what I got.
From Praxis works, the 50/36 may eliminate the rub, they will exchange the rings if I want to, the Shimano teeth of the outer ring is farther away from the inner ring is true, and they are looking into it right now, may come out with a new version.

From Rotor, the preload cap on the none drive side should completely tread in, mine is not all the way in.

From Shimano, other than the alignment of teeth, the Shimano outer rings have some kinda black coating, the coating will take out the noise if the chain is very close to the inside of the outer ring.

I took off the spacers on the BB, made sure the preload cap is all the way in, I didn't use the chainring washers.
I am going to stay with the setup, it was only minor rubbing from the 2 smallest cogs, I don't use these combo anyway.
Have I had a chance to start over again, I would keep the DA 7950 for sure, by the way, my bike is BMC SL01 54 Ultegra Di2.

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