Hello all
Apologies for the anorakyness of this post, but I thought I'd share my recent experience.
My bike is from 2012 so came with 9 speed tiagra. Over the years I've ran the following compact doubles:
1. Tiagra 9-speed crankset 170mm cranks
2. Tiagra 10-speed crankset 170mm cranks
3. Sora 9-speed crankset 165mm cranks
Notes. 1 was replaced by 2 when I needed a new bottom bracket after 6-8000 miles and there was some corrosion noted on 1 by the mechanic. I ran 2 until I had a bike fit and a shorter crank arm was recommended. The fitter couldn't get a tiagra with 165 crankarms, so I ran setup 3 until yesterday. The bike is running 9-speed tiagra front mech, cassette, shifters and chain. The rear dérailleur is now Tiagra 4700.
I was finding some difficulty going from small to big ring on crankset 3 (Sora), so after a service, the mechanic suggested I try the 10 speed tiagra rings with the sora crankarms. Hey presto, the shifting is nice and crisp again! He did note the chainrings on 2 were "more aggressive" than 3, which could be an explanation.
He put the 170mm crankarms on the sora rings, so I had a complete spare crankset. Before I stored it in the loft, I thought I'd get the weighing scales out.
1. Tiagra 9-speed crankset, tiagra 170mm arms - approx 800g
2. Sora 9 speed crankset, with tiagra 170mm arms - approx 900g
The 9-speed tiagra crankset is lighter than the Sora/tiagra hybrid. Shimano does trickle down tech from the higher groupsets to those lower down over the years. I'd heard rumours that sora is the same as 9-speed tiagra, but in my unscientific test it appears not.
TLDR: Tiagra is better than sora. If your bike has 9-speed tiagra and the crankset needs replacing, get 10-speed tiagra, not 9-speed sora.
Apologies for the anorakyness of this post, but I thought I'd share my recent experience.
My bike is from 2012 so came with 9 speed tiagra. Over the years I've ran the following compact doubles:
1. Tiagra 9-speed crankset 170mm cranks
2. Tiagra 10-speed crankset 170mm cranks
3. Sora 9-speed crankset 165mm cranks
Notes. 1 was replaced by 2 when I needed a new bottom bracket after 6-8000 miles and there was some corrosion noted on 1 by the mechanic. I ran 2 until I had a bike fit and a shorter crank arm was recommended. The fitter couldn't get a tiagra with 165 crankarms, so I ran setup 3 until yesterday. The bike is running 9-speed tiagra front mech, cassette, shifters and chain. The rear dérailleur is now Tiagra 4700.
I was finding some difficulty going from small to big ring on crankset 3 (Sora), so after a service, the mechanic suggested I try the 10 speed tiagra rings with the sora crankarms. Hey presto, the shifting is nice and crisp again! He did note the chainrings on 2 were "more aggressive" than 3, which could be an explanation.
He put the 170mm crankarms on the sora rings, so I had a complete spare crankset. Before I stored it in the loft, I thought I'd get the weighing scales out.
1. Tiagra 9-speed crankset, tiagra 170mm arms - approx 800g
2. Sora 9 speed crankset, with tiagra 170mm arms - approx 900g
The 9-speed tiagra crankset is lighter than the Sora/tiagra hybrid. Shimano does trickle down tech from the higher groupsets to those lower down over the years. I'd heard rumours that sora is the same as 9-speed tiagra, but in my unscientific test it appears not.
TLDR: Tiagra is better than sora. If your bike has 9-speed tiagra and the crankset needs replacing, get 10-speed tiagra, not 9-speed sora.
