All Sturmey Archer drum brake hubs from Ginkgo sport smaller 2.5mm (14G) spoke holes for superior spoke fit. An other singular feature are the availability of versions with 28, 32, or 36 spoke holes.
AFAIK every other vendor around the globe sells Sturmey Archer drum brake hubs with 3mm (13G) spoke hole diameter and 36 spoke holes only.
The ‘SA+’ hubs are the latest developement in Ginkgo’s ‘quest’ in improving the Sturmey Archer X-SD (70mm) and XL-SD (90mm) drum brake hubs for use in velomobiles (and tadpole trikes). Since heat build-up on long, steep descends can be a problem with drum brakes, especially with the closed wheel wells of Quest and Milan velomobiles, adding cooling fins and now heat sinks offers real world benefits.
Ginkgo offers their custom 70mm and 90mm Sturmey Archer drum hubs in various versions. All are available in silver or black anodised finish, with 28, 32 and 36 spoke holes, there are lightened versions, lightened versions with cooling fins and now the various versions of the SA+ with heat sinks.
The 70mm SA+ drums sport five heat sinks, while the bigger 90mm SA+ drums even got ten heat sinks. Compared to the stock drum hubs, the heat sinks are adding a 200 cm2 (70mm SA+), or 400 cm2 (90mm SA+) increase in cooling surface to the hubs.
Preliminary tests on a test bench where promising. Lutz stated, he couldn’t raise the hub temperature of the SA+ hub prototypes above 160°C in his tests.
I just called him on a different matter and when chatting about their new hubs, he mentioned they are eagerly awaiting the ‘real world’ results from their two velomobile test riders in the field.
Now to the slightly less desirable part: These Ginkgo SA+ hubs ain’t exactly cheap.
While Ginkgo sells the plain 70mm hubs starting at €77 a pair and the plain 90mm drum hubs at €88 a pair, the 70mm SA+ hubs start at €220 a pair and the 90mm SA+ hubs start at €270 a pair. The high-end version of the 90mm SA+ will set you back €340 a pair, while the high-end version of the 70mm SA+ comes a bit cheaper at €293.
All images: Ginkgo Spezialradteile
Disclaimer: I’m not in any way affiliated with Ginkgo. Just a enthusiastic user of Ginkgo’s 90mm custom drum brake hubs.
I’ve recently installed and tested water-cooling my drum brakes. While I ain’t got an actual heat problem, injecting 10-20ml of water directly into the brake drum, cleans the drum and brake pads and immediately restores braking performance.
Check-out this blog post for further information on water-cooling.