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Converting a GRX 1x to 2x

Old 09-14-20, 03:16 PM
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howardv
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Converting a GRX 1x to 2x

My bike currently has a GRX drivetrain (1x) with the FC-RX810 42T chainring. I want to replace this with the FC-RX810-2 dual chainring (31-48T) which costs about $225. Of course, this if for the whole crankset. Is it possible to just buy a 48T and a 31T chainring instead of buying the whole set again? Or is my current crankset not upgradeable?

And I can't believe the shifter/brake lever for the left side (ST-RX810-L) costs $270!!! Pretty pricey! The front derailleur and a new chain are reasonably priced, but just getting sticker shock at replacing crankset and lever!

Thanks for any advice.
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Old 09-14-20, 04:25 PM
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The RX600 and RX400 levers should work as well
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Old 09-14-20, 05:15 PM
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what's the reason for the conversion? if you want wider gear range, maybe try different cassette or chainring first
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Old 09-14-20, 10:31 PM
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I have found nothing stating that the FC-RX810-1 has the second BCD holes on it for the sub-34 chainrings. It might, but Shimano doesn't mention it, nor does any retailer.

ST-RX810-L $250
RX810-F $52
FC-RX810-2 $225
Ultegra Chain $30

...so about $560 to add a bit more gearing range. The cost of "upgrading" is IMO prohibitive. Doesn't help that GRX is new, so finding used/discounted is pretty much impossible.

Looks like it's time to N+1.
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Old 09-15-20, 05:24 AM
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Originally Posted by DrIsotope View Post
I have found nothing stating that the FC-RX810-1 has the second BCD holes on it for the sub-34 chainrings. It might, but Shimano doesn't mention it, nor does any retailer.
I looked into this a while ago; from what I gather, the arms are the same like with MTB cranks.

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Old 09-15-20, 07:54 AM
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That would save the OP about $85, as the 48/31 chainring combo (at least if you stick with Shimano) is about $140. That outer ring is absurdly expensive.

For me at least, $475 is a bit too much to spend to add another gear up front.
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Old 09-15-20, 11:09 AM
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The GRX 600 crankset is 30/46, would save you about 100 bucks and weighs 3oz more.
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