Hey. This page is more than 8 years old! The content here is probably outdated, so bear that in mind. If this post is part of a series, there may be a more recent post that supersedes this one.

For a couple of years, I had two bikes and lots of bike bits in the garage, gathering dust. I decided to roll the bits together and see what came out.

This did: a single speed with carbon fibre wheels, kind-of-cool handlebars, and a ‘lack-of-paint job’. It’s my commuter bike. It’s great – very light and nippy, but a bit of a bone shaker.

The Frankenstein, locked up at work. PS The gold tube is temporary. It’s got a bottle of wine it It was Christmas.

The Donor Bikes

Bike 1: 2008 Specialized Langster Limited ‘London’ Edition

2008 Specialized Langster London

This was a great bike. Single speed with an aluminium frame with a sprinkling of carbon fibre. Single speed with some funky handlebars and nice (slightly jingoistic ) paint job.

The Reason for Retirement: cracks around the base of seat post in the frame. I rode the seat too high for 8 years on a frame too small for me. It is not the first time.

Bike 2: Condor 2006/7 Pearl White Condor Something-or-Other (Squadra?)

Hydroformed aluminium frame with carbon rear triangle and front fork. I used this as a triathlon and race bike.

Yep. That’s me, on the Condor. Racing for Team GB – back when I was successful and a winner. Hum.

Reason for retirement: Suspected crack in the frame and a work bonus (=new bike). With a digital microscope from work, 2 years later, I finally got round to examining areas where I suspected cracking at a weld. I put felt tip pen over the area and wiped off then put the frame in a clamp and tried to distort it (and open crack) as I took shots on the microscope.  Verdict: No cracks. Lesson: Don’t buy white bikes (the paint cracks and you see it and get worried)

The Frankenstein

From the Condor:

  • Frame – stripped of paint down to bare aluminium. As the photos throughout this post show, the organic forms of the hydro-formed frame (albeit susceptible to weld cracking, maybe) are what make my Frankenstein.
  • Front forks (carbon)
  • Single sprocket from the rear cassette – the important one.
  • Rear cassette spacers

From the Langster

Chain, front gear and pedals. I sprayed the chain ring black (it was anodized blue). The chain was white already and kind of chunky, more so that a racing bike chain.


I used the Langster handlebars as they were a nice old-school, chromed. track-bike shape. But, as this photo show, they looked odd on the gangly Condor frame, & ergonomically: a ball-breaker. I ended up cutting them down and flipping them over.

I also used the brake lever and the brake caliper from the Langster, but to the front wheel (only). My ride to work it pretty flat, so braking is a rarity, bettr just to swerve. I bought special carbon fibre pads as the old one squealed and upset people. You can kind of see the Langster brake lever on the photo above.


  • ZIP 404 carbon fibre wheels from racing days
  • More spacers for rear cassette (from a bin round the back of a cycling shop)

Single Speed Conversion: Tensioner

Most of the work for the bike was just putting bits together – little thought needed. The challenging bit was converting the bike to a single speed. I didn’t what all the weight and hassle of the rear derailleur – I just wanted the two gears and the chain, like the Langster. Unfortunately, I could not make this work as the combination of chain and gears I had and the drop-down read wheels slots in the magincal Condor frame (Yep. I called it magical). The chain was either too tight, or it jumped – a bit like Goldilocks and the bears (kind of).

I ended up making a tensioning arm that pushes the chain out, keeping it tight enough to stay doing what it is supposed to.

The first cut was actually with a bent wrench (picked up off the road)  and some skateboard bearings on the chain. The spanner bolted into the frame where the rear derailleur used to be.  I have since learned that this is not a new idea – there are various variations of this.

I do not have a photo my spanner solution (it’s since reverted to being a regular wrench) – in a way I wish I’d stuck with it.

I ‘upgraded’ the spanner to a length 6mm bent aluminium strip. The holes don’t do anything: ‘aesthetic’ (in the same way Dr. Frankenstein could have used countersunk bolts in his monster’s neck) and they save weight. Yeah, about half a piece of toast and a glass of water. The bearings stayed for a bit, but they were really noisy as the links of the chain clattered over them. I am noise sensitive, so they had to go.

What I am using now is the same bit of aluminium but with an idler gear.  It’s actually an assembly made up of a small read-cassette gear and a plastic 3D printed ‘hub’. I actually made it for another project where I had a change of direction. (NOTE TO SELF: Finish automatic door opener).

The idler I used (from my Door Opener project). I just didn’t put in the worm screw when its installed on the bike, so the gear is free spinning.

The bike works great. The only issue is that over time/ distance the tensioner-arm, regardless of how tight I make things, moves up: The chain then loses tension and jump off. My current fix is every so often to nudge it down with my foot. I might put in something to permanently fix it…I might not – the foot thing has become a habit.