Cruzbike Sigma Repair

Current bike storage. This should be the spare bedroom!

 

My friend George passed away over a year ago, and he left a considerable number of bikes for his wife Christine to deal with. I've already passed on 3 of his Linear recumbent bikes with 2 of them raising money for OzHPV. I recently received another 4! At the moment I'm tackling the Cruzbike Sigma.  

This is not a typical Cruzbike. It is a brand that originated with John Tolhurst from Perth, Western Australia with the sale of a conversion kit to make a front wheel drive recumbent from a Y-Frame mountainbike. Now, under Jim and Maria Parker (USA), Cruzbike is a leading recumbent manufacturer, still making front wheel drive bikes. They only made one rear wheel drive bike and this is it.

Firstly to describe the bike I'm repairing and its problems: 

The back tyre was flat and that's fixed now.  A guide to the SRAM Imotion 9 gearbox in the rear hub showed me how to unhook and rehook the gear cable to remove the back wheel.

Seat base as drill template for Merbau timber.

 

The top part of the seat was cracked - the seat is one of the only parts the Sigma has in common with other Cruzbikes and this problem is relatively common - see here !  My fix was to make a replacement top seat part from Merbau  and strong plywood timber. I used the lower part of the seat as a drilling template and have done my best to alleviate stresses using rubber strips as suspension and metal plates to distribute load. I had some velcro strip, and the last step was to glue that to the timber to make the seat pad stick.

 

Lastly, the rack and rear mudguard was supported by cable ties fastened to the seat struts. This made seat adjustment difficult. The mudguard mounting points were changed, it was cable tied to the rack, and the rack is now supported by a strut which bolts on to the frame. Quite proud of that and it looks good, and the seat can be adjusted easily now..

 

So here is the rebirthed bike out on its maiden voyage. Everything worked well but the steering takes a bit of getting used to. I haven't done all the work I can on it (for example 2 cables should run through the large lower frame tube but they don't) but I'm satisfied with what I've done.

There are some remarks about the handling in the  Cruzbike Sigma Forum Page here, and an earlier post here describes John Tolhurst's desgn intentions for the bike.

 

I was intrigued by the lettering and designs on the Sigma, and one sticker says designed by John Tolhurst and Ron Witt.  I googled Ron and soon found this page, which describes Ron's strong desire for a recumbent bike that started after a bike accident when he was 16. The page also describes the Flash Recumbents which came from the Perth suburb of Midland and were made from about 1982 to 1992. (I had heard of Logo Trikes from WA, but not Flash!) One of the Flash bikes shown in the picture has large wheels and remote steering in the centre of the frame, a bit like the Wilson Bikes made in Melbourne.

Finally, a recent Facebook post from Glen in WA indicates there are about 3 Sigma Cruzbikes regularly on the road in Perth,  and a few extra ones lurking in garages.

I plan to sell this bike on ebay and will get the  auction going in a week or so with proceeds going to OzHPV.

Regards Steve Nurse