Originally Posted by
mawn
I want to replace my old -but still good- 52/42 Shimano 105 crank with a 50/34 Shimano Sora (cheap), because i need an easier gear.
is it worth it?
Will it effect the bike speed/performance?
The 50/34 Shimano Sora i want to buy :
https://www.decathlon.es/es/p/pedali...937?mc=8511779
My bike:
Have you checked that the current crank is just a double? The 52/42 rings are standard on a triple for this 105 (FC-55??) and your smaller ring looks that it has shift pins for shifting from a third small chainring. The actual part number should be stamped on the back of the crank arm, right next to where the pedal mounts.
Your RDER is also a longer cage (GS) version of the series normally used for a triple crankset.
Regarding your RDER, it should be rated for a 27 teeth largest sprocket on the cassette. Most people report going a tooth or 2 higher is possible.