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The S-Ride M520 derailleur is a ridiculously-huge-capacity rear mech for when you want to run a dinner-plate-size cassette or a tiny small chainring. Compatible with 11-speed Shimano 105 and GRX shifters and costing just less than £78, it might be your best (or only) option to go mega-wide-range with drop-bar shifters.
S-Ride is a Chinese component manufacturer which has a wide range of 8 to 12-speed mechs, flat-bar shifters and cassettes. It doesn't do drop-bar shifters, but in the case of the 520 mech here it advertises 100 per cent compatibility with Shimano's 105 and GRX shifters. GRX and 11-speed 105 both use a 1.4:1 pull ratio, so it's probably an error on S-Ride's part to list the 520 mech as a 2:1 actuation ratio.
My go-to gravel bike runs mostly Shimano GRX 600, but because the rear mech tops out at 42T on the cassette – nowhere near low enough for a 1X setup in the Highlands – I needed a Plan B.
For the last year I've run a Wolf Tooth GoatLink 11 to shift the GRX mech rearwards and downwards, allowing it to clear an 11-50 cassette. Paired with a 40T chainring, it gives plenty enough gear range to tackle 20 per cent estate tracks or long climbs with bikepacking luggage, and also the ability to bomb down smooth forestry roads without spinning out until close to 50kph. Yes, the setup takes time to fettle, and you'll definitely be needing a quality hanger alignment tool as at this blurry edge of the capacity envelope things can get shifty after even a small knock.
If this sort of 1X mega-range nonsense spins your freewheel, Shimano doesn't have a drop-bar answer. That's why Wolf Tooth invented the GoatLink, and why (I imagine) S-Ride invented the M520 rear mech.
The party piece of the 520 is the cage length – at 110mm it has to be the longest cage on the market. With the mech fully extended, the overall measurement from the centre of the hanger bolt to the bottom of the cage is 23cm, leaving just 8cm ground clearance on my Sonder Camino with 650B wheels fitted. This would probably be the biggest concern for the long-term viability of the S-Ride solution – but then again, in three months of riding, including a fair bit of rough trail with overgrown heather and whatnot, I've not caught it on any rocks or sticks.
At under £78 it's very well priced to deliver mega-range 1X shifting. My previous solution of the GRX 812 mech (£115, not available for six months) and the GoatLink (£30) is a whopping £67ish more. If you need a replacement for the 2X setup RX810 mech, that'll be about this time 2023.
S-Ride advertises the capacity of the 520 as '49T'. No, that's not a misprint of the largest sprocket – that would be 50T. It means the mech's capacity to soak up the overall difference in chain tension between the small-small and large-large combinations. What it's saying is that if you had an 11-50T cassette, you could run a double chainring with an 11-tooth difference – so, say, 40 + 29 – which would give you an insanely low gear while maintaining good top-end speed. Caveat: I haven't tried that, it's what S-Ride advertises.
The 520 has a non-adjustable clutch, which does a good enough job but is noticeably weaker than the Shimano version. With so much chain flapping about, I'd recommend going with a rubber or neoprene chainstay cover to keep noise down in the higher gears.
The cable entry port is almost horizontal with the chainstay, allowing for a clean line into the mech. What you don't get is any sort of barrel adjuster – probably the biggest omission people will notice. While forgivable on a mountain bike mech where you get adjustment at the shifter, for one specifically designed to work with drop-bar shifters it's a major niggle.
I inserted a Shimano CA70 adjuster into the cable housing run close to the mech to allow tweaking once installed. This could just as easily be installed at the handlebar end, but I'd already internally routed the bike. The top of the mech doesn't move as the cage shifts, so there's no need to build any flex into the cable outer loop.
You also don't get a cage lock that will hold the cage in a forward position to untension the chain when removing or installing the wheel. Cage lock is the feature I miss most when swapping between SRAM and Shimano mechs, and I keenly await the time when the patent expires and we can all have cage locks on every mech.
The finish of the 520 mech is high quality, with absolutely no slop in the cage pivots at all. This lends to easy setup and indexing and resultant crisp shifting. The shifting is heavier than the Shimano mech – to the point where I thought I'd got something wrong when in the workstand. Once out on the gravel, though, with right hand properly aligned with the lever, the extra force needed quickly became unnoticeable. Both upshifts and downshifts went smoothly even over rough ground, and in three months I only tweaked the barrel once to encourage a quicker downshift at the large end of the cassette.
The low, high and B-tension screws are all 3mm hex, and the hanger and pinch bolts 5mm hex. A nice feature – deliberate or not – is that the cable housing stop is sized for use with a ferrule. That means you can install an Outer Gear Casing Cap to minimise dirt ingress. Nice.
You need to be cognisant of chain length – on my size XL Sonder Camino, with a 50T largest sprocket and 40T chainring, a 116-link chain only just fits; it could really do with another link to quieten down things in that lowest gear. In this case you should look at using a 126-link chain and trimming accordingly.
The only user-replaceable part on the 520 mech is the jockey wheels – the UK distributor advises they are available as a spare part on enquiry. The jockeys run on bearings, so there's no skimping there with plastic bushes.
Over three months of riding about the Highlands I was happy with the S-Ride RD-M520C's performance. Gear changes were perfectly satisfactory, very occasionally needing a bit of finessing to shift to a larger sprocket. The additional effort needed over a Shimano mech went pretty much unnoticed after a few rides, and I only had to tweak the inline barrel adjuster once. The mech seemed pretty resistant to being pushed around by trailside growth, and the clutch worked well enough with no dropped chain occurrences.
As stated at the beginning, the Shimano-only options to achieve such a wide gear range on a 1X road/gravel setup don't exist, and adding a Goat Link increases cost and fragility. You can look at using a mountain bike rear mech with a pull-ratio converter like the £30 JTEK ShiftMate 8 – but the long-cage XT MTB mech maxes out at 46T. Shimano is very conservative so it would probably work fine with a 50T cassette, but again you're back to paying £130 for the Shimano-JTEK solution to work with drop-bar shifters.
If you're looking for mega-range or just a replacement mech that's actually available and will work with your 105 or GRX shifters, the S-Ride RD-520C is well worth considering.
A well-priced and capable mech for mega-range setups, if missing a barrel adjuster and cage lock
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road.cc test report
Make and model: S-Ride Rear Derailleur Over Long Cage 11 Speed Black RD-M520C
Size tested: 11-speed
Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?
It's for people running Shimano 11-speed drop-bar levers, who want to go mega wide range or just need a replacement that is available.
S-Ride says: '11 Speed Rear Derailleur. Clutch equipped rear derailleur designed for drop bar gravel bikes. Compatible with Shimano 105 ST-5800 and GRX-600/810 shifters."
Tell us some more about the technical aspects of the product?
* Extra Long Cage
* 2:1 actuation
* Clutch feature
* Aluminum cage, B-knuckle and outer link
* Total capacity: 49t
* Max. sprocket: 46/ 50t
* Min. sprocket: 11t
* Wt.: 269g
Feels and looks premium.
The heavier shifting is the only performance drawback I could detect.
Feels pretty solid and hasn't developed any slop.
Middle of the road – a long-cage XT mech is around 275g but has a beefier, rebuildable clutch.
For just under £78, it's good value; a lot cheaper than Shimano, though they have serviceable clutches.
Tell us how the product performed overall when used for its designed purpose
When riding you can't really tell the difference once used to the slightly heavier shifts.
Tell us what you particularly liked about the product
Mega-range. It's huge.
Tell us what you particularly disliked about the product
No cage lock or barrel adjuster.
Did you enjoy using the product? Yes
Would you consider buying the product? Yes-ish
Would you recommend the product to a friend? Yes
Use this box to explain your overall score
There's no adjustable clutch, no cage retainer and no barrel adjuster, but these are more setup niggles as opposed to operational defects. If you look at what it enables and how it rides, it's great, and well worth the money.
About the tester
I usually ride: Sonder Camino Gravelaxe My best bike is: Nah bro that's it
I've been riding for: Over 20 years I ride: A few times a week I would class myself as: Expert
I regularly do the following types of riding: cyclo cross, general fitness riding, mtb, G-R-A-V-E-L