Front Hubs with Drum Brake – What’s the Difference?

Danny1962

I’ve got a traditional style Dutch Town bike which I use for winter and foul weather commuting, it’s a solid old Batavus probably from the 1980s or 1990s. It’s a nice bike and I want to keep it going, but there’s some work needs to be done. The Sachs T3 rear hub is starting to play up and the drum brakes aren’t as strong as I’d like, so I have a plan…

Rear hub: To replace the 3 speed hub and drum brake with a Sturmey Archer 5 Speed with Coaster Brake (this one… http://www.sjscycles.co.uk/sturmey-arch ... prod19022/ )

Front hub: To replace the currently rather weedy drum brake with a new Sturmey Archer 90mm unit. But here’s the question... which one? There are a couple of types available which seem broadly similar but which aren’t identical.

I’m looking at either this one http://www.sjscycles.co.uk/sturmey-arch ... prod19008/

Spec: Front Hub with 90mm Drum Brake
Hub Shell Material - Steel
Bearing Type - Open Ball Cage
Axle Diameter - 3/8”
Axle Length - 136.0mm
Over Locknut Dimension - 100.0mm
Spoke Holes - 36
Pitch Circle Diameter - 102.5mm
Flange Width - 57.4mm
Spoke Compatibility - 13g or 14g
Weight - 1020g


Or this one http://www.sjscycles.co.uk/sturmey-arch ... prod22069/

Spec: Front hub with 90mm drum brake
Hub Shell Material - A356 Aluminum
Bearing Type - Sealed Cartridge
Axle Diameter - 9mm
Axle Length - 136mm
Over Locknut Dimension - 100mm
Spoke Holes - 36
Pitch Circle Diameter - 109mm
Center to Flange Right - 32.0mm
Center to Flange Left - 26.0mm
Flange Width - 53mm
Spoke Compatibility - 13g or 14g
Weight - 970g


Differences between SJS Part Number 19008 and SJS Part Number 22069 are:


Hub Shell Material: Steel (19008) vs Aluminium (22069)
Bearing Type: Open Ball Cage (19008) vs Sealed Cartridge (22069)
Axle Diameter: 3/8” [about 9.525mm] (19008) vs 9mm (22069)
Pitch Circle Diameter: 102.5mm (19008) vs 109.0mm (22069)
Flange Width: 57.4mm (19008) vs 53.0mm (22069)
Weight: 1020g (19008) vs 970g (22069)

My question really is about these differences, and whether they matter in practical terms.

Is a Sealed Cartridge bearing unit any better than an Open Ball Cage?

Do I need to worry about different Axle Diameters? Does it mean I need to use different fixing nuts? The one for the rear hub I’m thinking about is different again, at 13/32” . Does that matter?

As for the Pitch Circle Diameter… I’m assuming that if you drew an imaginary circle around the point where the spokes join the hub and measured the diameter, this would be the diameter of the pitch circle. Does the difference in diameter between these two hub units actually matter to me?

The steel unit is slightly cheaper than the aluminium unit but I’m more interested in compatibility than in price.

I’ve got steel spokes already fitted and I’m not worried about heavy weight or high performance.

And in principle does my idea of upgrading a solid and comfortable older bike with modern gears and brakes sound like a good one? It will probably cost over £200 for this work but I’m hoping the bike will run well for many years after it’s done.

nicklouse

The axel are the same.
As the hubs are unlikely to have the sam dimensions as he old ones new spokes will be needed so the hub dims do not matter.

Cone and up bearings are adjustable. Cartridge are just replaceable.

Maybe look for some ready built ones.

Danny1962

Thanks for that, nicklouse... it's obvious now you've said it, but it wasn't before. Looks like too much of a mission just now. Instead, I'm fixing the hub and will give the brakes a service while I'm about it.

Stateside there's clearly other people thinking like me, photogravity's got a really tasty piece of kit in post #12 and #23 on this forum. http://www.bikeforums.net/showthread.ph ... hilly-area

I've not ruled it out for the future though. I've parked the idea of a new SA hub and drum brakes for if/when the Nexus 8 speed hub gives up on my other bike. I won't want to make a direct replacement unless I can be certain Shimano have got their quality control sorted out with those 8 speeds.

corshamjim

If you do decide to get a new Sturmey front drum brake hub, it might be worth considering getting the X-FDD (or 90 mm XL-FDD) version that includes a dynamo too. On my Pashley I've ended up with a 70mm X-FDD dynamo hub on the front with a 90mm XL-RD3 3-speed on the back. I find the front brake fine once it's worn in. The 90mm on the back I tend to favour when descending long hills so it can do the brunt of the work without either of them overheating.

St John Street Cycles will do you a wheel build for about 40 quid including spokes. I found when I had one of mine done by them they still only charged a fiver for postage for the finished wheel too!

shouldbeinbed

+lots for hub dynamo too & I'd suggest marrying it to one of the Busch & Miller lumotec IQ range of front lights. I leave my rear fixed light on battery and the front alone on the dynamo is plenty good enough for me to see by on pitch dark country lanes in winter.