Evolution of the Purple Prayer
Posted: Mon Jan 15, 2018 9:58 pm
Back in 2005 I had the good fortune to win a KTM 640LC in a national competition which was awesome but it meant that only myself could enjoy the pleasures of hooning round the countryside, this seemed a bit unfair on the rest of the family. So, a well intentioned relative said, why not built a trike that my wife and then 13 and 15 year old daughters could come out on. Great idea. He had been looking through the local papers and spotted a GL1000 going for about £500 so we arranged a viewing. When we arrived, there were two bikes and we could take our pick. The first was quite tidy and un-messed with but the second had been tied to a chair and had leading link front forks and had been fairly extensively ‘customised’ by the owner as the first picture showed. Condition-wise it was a bit tatty with blowing exhausts, manky seat and crap paint, a good starting point to make a silly offer which after a bit of haggling a price was agreed. It was trailered home where it sat for 18 months while I thought about it.
It had to have 3 seats.
It would be as short as possible (not much longer than the original bike)
It would be below 400kg (for bike trike regulations)
It would be a bolt-on sub-frame so I could keep the original registration
It would use a Reliant axle.
This decided, I searched E-bay for a suitable axle and found one, complete with 3 alloy wheels for £95, and good deal, even though it was is Scotland. I had researched axle ratios and found that Reliant did a 3.32:1 which is very close to the GL1000 at 3.44:1 and this allowed me to use smaller car wheels. I also looked at rear brake conversions and opted for VW Golf GTi calipers and Nissan Sunny discs which spaced out nicely with the 10mm alloy carriers I made.
Time to strip the donor bike to a degree that I could place the axle and start designing the subframe. I mounted the bike level and steady on chocks and placed the axle on the garage floor in the approximate position I wanted it. Being a woodwork/metalwork teacher, I always advocated pupils making mock-up or models before starting the real thing so out came the MDF sheet and plastic pipe to start the job. The axle was locked to the rear footrest mounts so the geometry would always be the same during the build and I opted for a 5 link suspension with a Panhard rod.
I decided on the criteria for a design after looking on countless sites and examining professional and amateur build alike. I came up with a sort list of essential features:-It had to have 3 seats.
It would be as short as possible (not much longer than the original bike)
It would be below 400kg (for bike trike regulations)
It would be a bolt-on sub-frame so I could keep the original registration
It would use a Reliant axle.
This decided, I searched E-bay for a suitable axle and found one, complete with 3 alloy wheels for £95, and good deal, even though it was is Scotland. I had researched axle ratios and found that Reliant did a 3.32:1 which is very close to the GL1000 at 3.44:1 and this allowed me to use smaller car wheels. I also looked at rear brake conversions and opted for VW Golf GTi calipers and Nissan Sunny discs which spaced out nicely with the 10mm alloy carriers I made.
Time to strip the donor bike to a degree that I could place the axle and start designing the subframe. I mounted the bike level and steady on chocks and placed the axle on the garage floor in the approximate position I wanted it. Being a woodwork/metalwork teacher, I always advocated pupils making mock-up or models before starting the real thing so out came the MDF sheet and plastic pipe to start the job. The axle was locked to the rear footrest mounts so the geometry would always be the same during the build and I opted for a 5 link suspension with a Panhard rod.