Tuesday, 1 March 2011

I built this! - (Hopper Pt 8)

In my last post about the Hopper the bike was pretty much done and working, but I was having trouble with the back wheel. Not only did it destroy a pair of Sturmey lock washers it was also had a tendency to try and pull the back wheel over to one side and cause an unhappy marriage of tyre with chainstay. After a lot of trial and error me and my brother worked out a combination of:

  • Spreading the rear triangle a little
  • Dishing the wheel a bit more
  • Fitting SRAM lock washers
  • Using a ½ chain link
  • Removing the sprocket spacer on the hub so that the chain line was straighter.

I think this last point is the real deal breaker.  The Hopper’s Bottom bracket axle is quite short, whilst the new SAB steelite hub is a bit wider than a standard AW hub. This meant when the bike was rebuilt the chainline was way off. Even with all the changes it still isn’t track-bike-ishly straight, but its close enough to stop the wheel from wanting to cant off to one side when under a lot of torque. Which in turn led to having to overly tighten the axle nuts and end up crushing the lock washers. The half link in the chain allowed the wheel to sit further back in the dropouts and spreading the rear triangle a bit gave yet more room for error.

A little apprehensively, I rode it the 8 miles into work for the first time this morning and it all went smoothly. The X-FD & SAB brakes are fantastic – silent & powerful but very easy to modulate. The 46t-18t gearing on 20” bmx wheels is just right for cruising along at 12+mph in 3rd meaning the two lower gears are just right for setting off and going up the steep bits. I didn’t feel like I was spinning out on the down hills either – it’s a cruising bike not a racer. The rebuilt SAB hub ran smoothly and changed gear perfectly, so it’s new axle and a re-grease has done the job.

a round up of the components:
New: stem, saddle, X-FD hub, spokes, kickstand, cables, chain & tubes
Laying around the garage: handlebars, grips, pedals & sprocket
Secondhand off ebay: 90's SAB hub, BMX rims & tyres
Original: Frame + forks, chainring, cranks, mudgaurds, shifter & brake levers

Here’s a few shots of it finished (and more reliably working this time!). The Hammerite paint is looking good in a homemade kind of way. I've also bought a tin of gold enamel paint to do some pin-striping but cant make my mind up whether to do it or not yet.

The ride home was just as great, but the lumps and bumps of Manchester's roads will soon weedle out the weak areas. & I did subtitle this blog ' Making, Breaking and riding bikes in Manchester' so here's the bit that broke. The original mudgaurd hanger was probably the rustiest part on a very rusty bike, but also a fuss to replace. So I cleaned it up a little and painted it. However it got bent the other day and gave up on the way home. Luckily I had an emergency zip tie in my bag.


  1. Nice job Jim :>)

    I gave the Twenty an airing today around Hyde.

    A different experience than the big wheeler!

    Twas fun too.

  2. Nice! Just wondering if you have ever seen a Hopper bike that has "HOPPER" on the front sprocket? The hub is sturmey archer 4 speed with 58, which I read means 1958. I'm in the US and there is almost no info on this. Thanks!