Conical front wheel

Previously Jim Brierley wrote:

Hi all,

I'm currently building a Norton CafÃ? racer based on a 750 Atlas and I plan to use conical wheels from the late Triumph/BSA models. The rear wheel conversion seems to be well catered for, with either a special wheel spindle with flats machined on it, or a purpose made box section alloy swinging arm.

However, I've not seen any parts readily available to convert the front conical hub to fit the Norton roadholder forks.

Does anybody out there have any experience in such a conversion which retains the BSA TLS brake plate. There's an article in this months Classic Bike Guide which shows a Triton with a conical wheel fitted with a Commando brake plate, but I don't want to go down that road as the BSA TLS brake offers much better performance.

Hi Jim,

Much better performance than a TLS commando? Wonder why we used to refer to these as "comical" hubs back in the day.

Best regards for Xmas,

Chas

I rebuilt a BSA Thunderbolt a few years ago and the conical hub brake was dreadful. I believe you can get longer operating arms to work the cams but they are very expensive. The conical wheel is clamped between the fork legs and the end caps so the left to right position is taken care of. The norton spindle pulls the whole plot across to one side. So some kind of new spindle would need making to clamp the whole Conical hub, bearings and brake plate across to the side. Must be do-able. Buy a lathe (-:

Hi Jim, et al,

The big difference between the BSA /Triumph and most other TLS brakes is the operating system. The BSA type is 2 single leading shoes that are pulled together so the pressure equalises on both shoes. This seems a good method but lacks the vital factor of a full TLS which is the servo effect of a rod connected set-up. Peter Williams wrote an article about 3 years ago in Roadholder describing how to set them up. A properly set up TLS should be able to lock the wheel at walking pace. The big problem is getting it just right and once it is right don't touch it unless you have to. I would think you could convert the conical set-up to rod connected and there may be something already on the market. Regards, Richard.

Using the BSA/ Triumph conical hub with roadholder forks is not difficult.When I built my 88/99 from a pile of bits, I found that I had a BSA/Triumph rear conical hub so Rather than buy a standard Norton front hub, I aquired a BSA/Triumph conical front hub. The original spindle is 15.875 mm diameter, the Norton one 17 mm, If I rember correctly. I changed the wheel bearings from Hoffmann 120 to 47mm od, 17mm id, 14 mm width double sealed ball races. I also used a spacer between the two bearings to resist thrust. A friend with a lathe made it in Dural. The brake plate on the BSA/Triumph set up is located by a stud which slots into a hook on the fork slider. I removed this and found a friendly expert welder to fit to the brake plate a section of dural about 45mm long and a sliding fit into the slot in the roadholder slider.

I seem to remember that I needed to raid my stock of odd washers and spacers to get a perfect fit. Finally I drilled and tapped a small hole in the slider to take a small grub screw to take up any slight play between slider and brake plate.

The hub was then spoked into a Borrani WM2* 19 rim and looks good. The brake, properly set up using the adjustment cams is pretty good, The bike is quicker than I am.

This pictures shows the final result.