Tuesday, 20 July 2010

Nexus 8 Build (part 1)

I'd been thinking of building up a hub gear bike for the everyday commute for a while, when I came across the bargain singlespeeds they are selling at Decathlon.

£69.99 sounded to good to be true, but after a quick inspection and ride up the aisle its easy to see that, for the money, its suprisingly decent piece of kit.

Heres the basic bike, it's a B'twin Vitamin in a lovely bright orange! (ignore the floppy chain, I'd already started the build when I took the photo)

So the plan was, get the bike then scout out ebay for potential hubs. Plenty of choices available. 3 speed Sturmey Archers?, 5 speed sachs?, nexus 7 or 8 speeds among others. Initially I thought it would make a good project to try and do my first wheelbuild, but when a full 26" wheelset with a Shimano Nexus 8 speed & tyres came up and decided wheelbuilding would have to wait for another day.

Here's the wheelset:
They came with a 20 tooth sprocket, twistshifter and decent Schwalbe City Jet tyres.

Now the 20 tooth rear sprocket combined with the 36 tooth chainring already on the Vitamin would give me gear inches of approx 24-75, which is fine, but not quite high enough for what I think I would like. So a smaller rear sprocket will be getting bought later on.

The Vitamin came with a an 18 tooth bmx style freewheel on the rear, meaning I would have to extend the chain by a couple of links. Luckily I an sram pc-1 leftover from when I changed the chainring on my Brompton. The sram chain was even the correct length already.

Slotting the rear wheel in is pretty straight forward. These nexus hubs have a mechanism on the drive side which rotates centrally around the axle in order to change gear. As opposed to the in and out mechanism I'm used to seeing on Sturmey Archer hubs. This Shimano solution works very nicely though and and is easy to adjust as there are a full set of yellow and red markers which will all line up correctly when the Hub is in 4th gear (1:1 Direct Drive)

There are a variety of anti turn washers for these hubs, depending on what kind of dropouts your frame has. The idea of the Anti-turn washers is to align the shifting mechanism in the correct direction and keep the axle fixed in one direction. Mine has the traditional horizontal dropouts because it is built to be a single speed, which is perfect because it means less fuss for me and it makes is easy to adjust the chain tension. Virtually any older frame will be similar though. As usual with cycling, for more detail turn to Sheldon.

Here is the locknut that attaches to the shifter cable and slots into the mechanism on the side of the hub:

Once the rear wheel was in it was just a case of routing the cable down the chainstay arm and up the frame. Cable ties for that job. making sure the cable routed away from the chainring, just in case.

Another beauty of hub gears.....only one shifter to worry about. Easy to mount on after moving the brake lever a bit to give enough room for the grip to go back on ( I might swap the grips later on as they feel a bit gummy for my liking)

Here's the job done. Simple. when I orginally bought the wheelset I had been thinking I would swap the tyres for some dependable Schwable Marathons, but after seeing it complete I really like the extra chunk that the 1.95 city jets give, so I'll be keeping them for now.

Just waiting for some black mudgaurds to come in the post and it will be ready for all weathers.


  1. Looks good. I've ridden 2 nexus 8 bikes in the past, one was a Revolution Pathfinder Nexus for a test ride and the other was a loaner for a tour of Brussels. Both times the Nexus was lovely, especially as they were my only experience of internal gears at the time. I don't enjoy rideing derailleur geared bikes as much anymore.

    One day I'll get the Rohloff Speedhub, or the NuVinci CVP. When I'm rich

  2. Evening Mr B - guess you're ex-directory 'cause I couldn't find your number in the phone book ;>D

    I had a chat with a Vitamin owner a few months ago outside Tesco in Stalybridge a few months ago? (I was with my daughter on our tandem) - was it yourself?

  3. Nope, I'm afraid it wasn't me. Although I did see a bloke riding one through Hyde town Centre a few weeks back. I'm not sure when they started selling them, but for that price I wouldn't be suprised if there are bagfuls of them dotted around Manchester already.