Shutter Precision SD8 Hub Dynamo
399g £99.99

The Shutter Precision SD8 Hub Dynamo is claimed to be “ideally suited to 20-inch wheels at 6V3W and perfect for 6 bolt disc brake” but don’t rule it out if you’ve a 26 or 700c bike(s) in mind. While the total output dips to 6V 2.4W, in practical terms and in common with its SL9 cousin, I’ve only noticed a tangible dip at very slow speeds - groveling along at 9mph on a long climb, or slower. 13mph plus (a steady tempo that most riders should easily keep) and I’ve had the full 1300lumens from the K-lite family of dynamo lamps. 

Pros:  Lightweight, low resistance at very slow speeds, compliant with stVZO standards, nicely machined and finished.

Cons: Minor loss of output at very slow speeds on 26 and 700c, contact, rather than labyrinth, weather seals

sp hub dynamo bike bicycle light

Materials/Specification

Designed with the stresses of disc brakes in mind, the SD8 is engineered for optimal performance with small wheels, while still being a solid, viable option for 26inch and 700c hoops. It also complies with German stVZO regulations, which are becoming increasingly influential elsewhere. Designed for the stresses of disc braking, the SD8 is machined for 6 bolt rotors (while the SL9 sibling  is for centre lock). However, you can also go the centre lock route, using an aftermarket adaptor. There are a lot of similarities with its siblings. The shell is beautifully machined from 6061 aluminium alloy, albeit “only” available in a choice silver, or black anodised finishes. 

However, this should complement, or contrast handsomely with most colour themes. Ours has 32 holes but 24,28, and 36 drillings are the alternatives and should cater for most contexts, save perhaps for tandems, or very heavily laden cargo bikes, and assuming you’re using hollow, not bolt-through axles. 

Sealed, fit n’ forget cartridge bearings turn on hollow aluminium alloy axles, which keep weight low and costs sensible. In common with its siblings, and indeed, other brands, once they’re cooked, the hub must be returned to the factory for overhaul. Longevity will depend upon several factors- rider weight, style and conditions being the most obvious variables. 

Talking of which, the contact seals are designed to keep out waterlogged roads and heavy rains but not river crossings, or jet washing. Shutter Precision tell me they’ve had endurance riders pass the 15,000mile mark without missing a beat. I hit 18,000 from the PD8’s bearings before they got sloppy

bike water flod

These were exposed to snow, slush and freezing temperatures, not to mention the odd (unavoidable) flooded road. The finish still looked glossy, sharp and blemish free. Shutter Precision hubs also come with a two-year warrantee as standard. Some brands, including Shimano employ Labyrinth seals, which are more effective in engineering terms, at sealing lubrication/grease in and keeping the elements out. 

 

The SD8, in common with its siblings comes sans skewer. This may irritate some but frankly, I’m inclined towards the aftermarket locking type, especially if you’re commuting, or don’t want to think about a second lock when dropping by the café' mid-ride. In terms of connector, I’ve had no problems with Shimano (when running an Exposure Revo lamp) and of course, the K-lite family.

I did add a precautionary blast of Motorex Jokker 440-a synthetic maintenance spray that doesn’t contain PTFE, so safe on electrical components. Traditionally, I’ve gone for a lick of Vaseline, which will also insulate and ensure excellent connectivity through the foulest weather. However, even traces tend to attract grime.

wheel rim spokes hub dynamo buld cycle bicycle ike

Build/Context    

 

I am all about future-proofing my fleet, where practical and economic. Ursula, my rough stuff tourer is based around a late 90’s cross country mountain bike frameset and 26inch wheels. While hardly rare (having been the default for over 30 years) 26 has been overtaken by 27.5 and 29inch. 

In common with 27”, choice of rim is becoming more limited. I was looking for something durable, with machined sidewalls, allowing the choice of a cantilever, or disc. Afterall, life’s about options...Rigida Sputnik was my obvious default. 

bike bicycle wheel tyre tire

However, a Ryde Andra 40 proved the next best choice. These are another hard wearing rim. 25mm wide, they’re intended to withstand the rigors of cargo and family bikes, without being hefty in the sense downhill rims can be. Slightly overbuilt for purpose perhaps but laced 2-cross by Mick Madgett, I knew they’d be ultra-dependable.

Resistance 3.75/5

Resistance was low, as I was expecting, true to claims, lower than the PD8 up to around 10mph, whereupon it was level pegging. Much the same story, compared with the Shimano Ultegra that has been Ursula’s default for over a decade. (Interestingly, the Shimano is reckoned to offer 53% efficiency at 15kmh). 

shimano dynohub hub dynamo bicycle cycleb bike

Resistance was more pronounced than its SL9 cousin, but I’d expected this. However, as I suspected, the SD8 and K-Lite Ultra-Light Dynamo Bike Light  proved a good pairing, producing a good spread of light, albeit not rivalling the outright punch of the 1300lumen K-Lite Bike Packer Pro V2 which has been Ursula’s default for six months or so now.

 

Output 3.75/5

Given the 6V 2.4 W specification, I was expecting a little trade off at the lower speeds, say when climbing and that’s precisely what I got. Much will depend upon the lamp, of course. At 13mph plus, I got the full 1300 from the K-Lite Bike Packer Pro V2, easily attainable and all day long, as required.  

bicycle light beamshot road dynamohub

However, bigger climbs can knock momentum and I did notice some discernible drop in output when grinding along at 9mph.

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Sooner than the SL9 but in terms of the K-Lite Bike Packer Pro V2, we’re still talking around 400lumens, which isn’t going to be an issue in the seen with sense, even along the darkest lanes and at 5am. 

I could also navigate at this pace, although I tend to run a helmet light, such as the Sigma Buster 2000, in the eco (300 lumen) setting, just so I can read road signs, tighten fasteners, or make similar adjustments by the roadside.

 

Over the climb and whizz, the lamp’s back at full potency. Similar story with the 800 lumen Exposure Revo, so in my experience over the past 600miles, this is only likely to be noticeable, if you’re battling near vertical climbs with a trailer en tow. I should also point out, with the helmet mounted lights off I had no issues being seen by other traffic and from a comfortable distance. 

On the flip side, through slow moving, congested sub/urban traffic, this is all a moot point, right down to single figures. The stand light function, common to modern dynamo lamps further nullifies this. At the other extreme, after a few days dormant, the hub’s lower resistance brought light, rather than glimmer (albeit a few hundred lumens) quicker, which is welcome and reassuring. As regular readers know, regardless of whether I’m using a high-power dynamo, or a rechargeable mode, there’s always a blinkie playing backing singer-just in case. 

Our December/January test period has been decidedly wet and slippery. Many lanes and routes were awash, not engulfing the hub by any means but deep puddles were making a splash. I’ve also been whizzing through some gentler forest trails and boggy, churned bridlepath. Temperatures were also hovering just above and indeed, below zero. As we’d hope, the hub and therefore, systems have never missed a beat.

   

Durability 3.5/5

Difficult to speculate on long term durability but the SD8 seems every bit as well-sealed from the elements as its siblings, which are still serving me well, several years down the line. However, the two-year warrantee should inspire confidence. It can be rebuilt at the factory and their UK distributors (Ison Distribution) offer a returns service. As I’ve intimated earlier, I’d prefer labyrinth sealing and would happily pay a few pounds more, for the benefits.

Value 4/5

A penny shy of £100 is competitive, given the specification. It’s worth noting that the SP SD8 is optimised for small wheel bicycles but if you’re looking for 26/700c specific then Shimano Alfine DHS501 comes in at £119.99 and is also available in either black, or silver. It features labyrinth and contact sealing. However, it’s also a good 200g heavier than the SD8.

SON XS (Brompton) comes in at £209 and comes with a five-year warrantee and claimed 60% efficiency at 15kmh, compared with the SD8’s 72%. If you were on a budget and running rim brakes on a larger wheel build, JTEK Dynamo Hub features sealed bearings 6V3W and is £79.99, sans skewer. 

Summary 

All told, I’ve been pleasantly surprised by the Shutter Precision SD8. Its competitively priced and seems to deliver a decent, consistent output, compatible with my high-power lighting. Being picky, I would prefer labyrinth seals, like those used in Shimano systems but I’ve still returned several years hard use from its siblings. 

The SL9 offers lower resistance and maybe worth the additional cost if you were seeking a super compact, lightweight option, say for a posh audax, or training bike. Similarly, (and talking larger wheeled machines) at the other extreme, something like Shimano Alfine might prove a better match for general riding in hillier regions, especially if you are hauling trailers or heavier loads.

Verdict: 3.75/5 Lightweight dyno hub with a competitive price tag and decent all-round performance.

Michael Stenning

 

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