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SP “switchable” hub dynamo (dynohub) PD-7 (for disc-brake 700c/26″wheels)

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The smoothest known to man! * Quick release not included. The SP PD-7 “Switchable” hub dynamo The PD-7 is the only hub dynamo that lets you have it both ways. One of the earliest hub dynamos developed by SP is the ingenious 7 Series hub dynamos which merge a robust high-efficiency hub dynamo with a…


The smoothest known to man!

* Quick release not included.

The SP PD-7 “Switchable” hub dynamo

The PD-7 is the only hub dynamo that lets you have it both ways.

One of the earliest hub dynamos developed by SP is the ingenious 7 Series hub dynamos which merge a robust high-efficiency hub dynamo with a switch that mechanically disengages the generator when not in use. Although switching the generator off does not eliminate 100 percent of drag from the hub dynamo, the appreciable effect is literally just a hair short. The SP 7 Series hub dynamo provides the benefits of a reliable hub dynamo, but without efficiency-robbing drag when not in use.


How much energy are you saving when the generator is switched off?

Although the 7 Series hub dynamo is not as efficient when in use as the 8 Series hub dynamos at 60 rather than 72 percent (i.e. watts of mechanical energy converted directly in watts of electrical energy – minus wasted muscular effort that would otherwise be propelling rider and bicycle forward), it’s the ability to turn the generator off that gives the 7 Series hub dynamo a real-world edge. Still, 60 percent efficiency is nothing to scoff at as it means that the P-7 series hub dynamo is roughly 10 percent more efficient than the best Japanese hub dynamo we are aware of. This measure is recorded at the “gold standard” 15 km/h (9.3 mph) specification set under the rigorous German StVZO standard for hub dynamos.

It is when lights are off – which is most of the time bicycles are ridden – that the SP 7 Series hub dynamo truly makes its (under)statement. The 7 Series hub dynamo produces well under half the drag of the top 2.4W German hub dynamo at 15 km/h. At 30 km/h (18.6 mph), however, it produces nearly 6 times less drag. This gap widens significantly when the comparison is with the top Japanese hub dynamo at nearly 10 fold less drag when measured at 30 km/h. Notably, these efficiency gaps widen considerably at speeds above 30 km/h – we encourage you to verify this result for yourself.


About Shutter Precision

Shutter Precision (SP) was founded in the classic spirit of a “garage based” Silicon Valley style start-up. Its founders are young engineers with substantial expertise designing and producing the sophisticated micro motors that articulate fragile shutters in high-end cameras. Their adventure into the bicycle field began in 2007 with a vision to bringing their expertise to crafting the most efficient and technologically advanced hub dynamos for powering lighting systems and electronic devices on bicycles. When they initially gathered their collective personal savings together with loans from family, friends and friends of friends, they had not anticipated that their journey of financial uncertainty, toil and sweat would also include (sporadic) ulcers.

By 2011, however, their painstaking efforts had culminated in a diverse line of state of the art hub dynamos incorporating the latest advances in the field of micro-motors – i.e. technologies resulting from large industrial scale R&D programmes that would have been cost prohibitive for the bicycle field.

It is the stuff of legend that when the design concept incorporated by SP engineers in their generator mechanism was originally reviewed by their world-renowned German competitor in patent format – it was then considered (with a sigh of relief) technically infeasible for manufacture. Since then, SP hub dynamos have passed from CAD-based “proof of concept” exercises through extensive lab testing of numerous prototypes and finally rigorous real world field-testing of final products. Testing is on-going even today via sponsorships of top endurance cyclists in Australia and the UK. This regimen has not only proven the feasibility of the SP hub dynamos for manufacture, but confirmed their superiority in efficiency and mechanical rock-solidness. At EuroBike 2011, even the previously incredulous greeted the founders of SP with (gregarious) approbation.

The axiom that “more complexity is not always better” is nowhere more true than in the case of the 8 series hub dynamos. In fact, the design of the generator in these hub dynamos incorporates fewer parts, is mechanically far simpler and is more easily manufactured than existing world-class hub dynamos. Excruciating efforts directed towards product and manufacturing process engineering has made 8 series hub dynamos cost viable for production entirely in Taiwan despite strong price competition vis-à-vis hub dynamos from large international brands produced in China.

The heart of the SP generator mechanism is a solid high-specification magnetic ring that rotates alongside copper coils as the wheel turns to produce electricity. This novel mechanical design is crucial as most modern hub dynamos rely on a number of magnets bonded onto the inside of the hub’s shell. When hub dynamos breakdown, it is often due to failure of the bonding adhesive holding the individual magnets in place – such breakdowns are more common in colder climates that accelerate deterioration of bonding adhesives. The design of SP hub dynamos makes this type of catastrophic failure virtually impossible.

Who says you can’t have it both ways.

Whether you pride yourself on having the best of everything, or on selecting purely based on value versus performance, SP hub dynamos “have your back”. This is true even if you are a crusty old curmudgeon wedded (if not welded) to the ideal that durability is the only factor worth considering.

The “less is more” philosophy held dear by the creators of SP hub dynamos is clear in their mechanical design, beautifully understated silhouette and undeniable proof that price is not always prerequisite performance … much less quality and durability.

To the best of our knowledge here at Intelligent Design Cycles, SP hub dynamos are today peerless in the world bar none.

The Shutter Precision Two Year Warranty

All SP hub dynamos come with a full two-year limited warranty against manufacturer defect beginning from the date of purchase. SP stands behind their products and will repair or replace free of charge products found to be defective. High-mileage users are particularly valued customers and hubs that have not suffered a defect, but simply have worn bearings due to extensive use, can be sent back to the manufacturer for new bearings free of charge within the two year warranty period (customer pays for two-way postage). Similar service after the warranty period is available for a reasonable USD 30.00 (the amount includes the return postage). This is the best service policy we are aware of in the industry. Please note that SP hub dynamos are not user serviceable.

Intelligent Design Cycles proud to be an agent for SP hub dynamos. With the exception of EU member countries, Intelligent Design Cycles is an authorised agent for SP products worldwide and is the exclusive distributor for SP products in Australia. In short, dealer inquiries are warmly invited.