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GRX Crank needs new F derailer ?

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GRX Crank needs new F derailer ?

Old 08-13-22, 05:51 PM
Steve B.
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GRX Crank needs new F derailer ?

A buddy has a vintage Synapse, 10 spd. 105 group, with a 34/50 crank, wants lower gearing but desires/wants to keep his road oriented cassette with closer cogs as we ride in flatish terrain mostly. I suggested swapping his 10 spd. 105 crank to a GRX 10 spd. 30/46. He has that ring setup on his Topstone gravel bikes, likes the crank.

Question is, besides a new b-bracket, will he need a new F derailer as well. I'm aware the GRX cranks sit out an additional 2.5mm and there seems to be some question as to whether you can get away with the existing derailer, or will he need to swap to a FD-RX400 ?.

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Old 08-13-22, 05:57 PM
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Back off the H screw and see if the FDER will move 2.5mm further out.
In reality, you need a bit more.
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Old 08-13-22, 06:37 PM
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Bikin green makes 46/30 chain rings. Thats the rout i went on my gravel bike.
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Old 08-13-22, 08:15 PM
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Some people get by with the original FD, others find they need the GRX. Best advice is to buy the FD along with the crankset, just in case it's needed. If the original FD works fine, return the GRX FD.
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Old 08-14-22, 07:25 AM
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The other question is whether a GRX front derailleur will work with the current front shifter
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