Will it fit your bicycle?

Fig 1

Fig 2

Fig 3

Fig 4

Fig 5

Here are some ideas to illustrate the Ped-Power Sprocket concept. It has worked for me and might work for you.

Bike frame (suit common 2-stroke bike motor

Take a good look at the bike that you want to fit the motor on. If it is not suitable, you may waste a lot of time on it.

Here are some basic frame requirements:

• fitting the motor into the front triangle of the bicycle frame is good for balance;
• the rear wheel must NOT have a disc brake or hub brake (Fig 1);
• the frame must have straight chain and seat stays. Stylish 'concave' stays are not suitable (Fig 3);
• the horizontal distance between the cranks must exceed the width of the body of the motor.
• vertical dropouts are preferred, but the traditional style of dropout (favoured by non-derailleur geared bikes) can be used provided that considerable force is applied to close the quick-release spike.
• the frame must be strong enough. Very light frames are unlikely to be suitable. The most suitable frames are those marketed for popular all-purpose.
• Make sure that you have a good set of brakes.

Wheel requirements

Wheels come in a wide range of configurations and sizes. Fortunately, the wheels suitable for the Ped-Power Sprocket are commonly available.

Hubs must have tapered wheel bearing housings. The axle boss (Part C12) must fit over the hub (Fig 4). Hub ends with that are not tapered are not suitable. These unsuitable hubs are often found on cheap entry-level bikes and tend to be made of steel and painted black.

Wheel configurations determine the geometry of the Spoke Fixture Assembly and are based on standard lacing of spokes, where each spoke crosses three (3) other spokes (Fig2). Visit Sheldon Brown's excellent web site for more information on lacing of spokes. Wheel configuration variables are:

• Number of spokes in the wheel (S);
• Hole circle diameter of the spoke holes the hub (HCD); and
• The effective rim diameter (ERD) of the wheel rim measured from spoke nipple to spoke nipple.

The SF1 Ped-Power Sprocket is for wheels with the following parameters:

* Number of spokes (S) = 36;
* Hole circle diameter (HCD) = 45; and
* Effective rim diameter (ERD) = range 500 to 610.

It turns out that the design of the Ped-Power Sprocket is very dependent upon 'S' and 'HCD' but not 'ERD'. Ped-Power Sprockets to suit other sizes can be manufactured, depending upon interest. In particular, a Ped-Power Sprocket to suit a common 32 spoke wheel is feasible.

Sprocket clearance to frame

The Ped-Power Sprocket will fit many popular bicycles with readily available hubs and the common 135mm dropout/over-locknut dimension between the left and right stays. Note that:

• the Ped-Power Sprocket fits in the space on the left side between the rear wheel and stay and chain stay;
• Dimension 'A' between the left and right chain stays is the main indicator and must be a minimum of 110mm at Dimension 'B' = 90mm from the axle centre.