Bike Generator Construction Plans (5/10/2014)Aaron DebbinkMatt Randal

Safety/Tools

When building the bike stand, we had access to a table saw, mitre saw, drill, as well as a toolbox full of hand tools. If you don’t have experience using these tools, find someone who does and have them help you. A good rule of thumb, if there is ever a particular machine or type of cut that you don’t feel completely comfortable doing, don’t do it.

Steps for Construction

Wood needed for entire construction: one 4’x8’ ¾” sheet of plywood, one 8’ 2x4, one 8’ 2x6, and one 8’ 2x8.

1. Order the motor, pulley, and press fit bushing (see appendix for ordering and price info).  Take the sprocket off of the motor shaft. This is really difficult to do. When disassembling the motor try not to take the entire motor apart. Once the sprocket is taken off of the motor shaft, hammer the press fit bushing onto the shaft and attach the pulley using the set screws. You may have to hammer the pulley on as well. If this step intimidates you, just buy a scooter motor without the sprocket or with a removable sprocket / pulley.

2. Buy materials for the bike stand and order all of the parts for the electronics board.3. Build the stand.       4. Put together the electronics board.5. Enjoy your energy independence.

Bike Stand Construction

Materials List:Material Size / Length Quantity Part Letter

¾” plywood 18”x32” 1 A¾” plywood 12”x16” 2 B¾” plywood 6”x13” 1 C

2x4 pine board 8 ¾” 2 D2x4 pine board 10 and 1/8” 1 E2x8 pine board 15” 4 F2x6 pine board 20” 2 G

Construction Screws 1 ¾” 1 box HConstruction Screws 2 ½” 1 box I

½” Hex Head Carriage Bolt (fully threaded) 5” 2 J½” Nuts - 4 K

½” Large Washers - 4 L½” Bolt Couplers - 2 M

½” metal conduit coupler - 2 N3/8” Hex Head Carriage Bolts (not

fully threaded) 3” 4 O3/8” Wing Nuts - 4 P3/8” Washers - 8 QHose Clamp ½” to 1” 2 R

2x4 pine board 16” 2 S2x8 pine board Cut to size (approx.

15”) 2 T

Construction Details:

1. Construct the side support structures using parts B, D, F, H and I.a. Attach both 15” 2x8 boards (F) to the back of the 12”x16” 3/4” plywood

board (B). Attach with the 1 ¾” screws (H). See figures 1 and 2. Optional: You can cut the 2x8’s at an angle like in the diagram if you want to reduce the overall weight of the bike stand.

b. Slide the 8 ¾” 2x4 (D) in-between the 2x8’s (F) and attach using the 1 3/4” screws. See figure 1.

c. Drill a hole using a ½” bit for the hardware that will attach the bike wheel to the stand. See figure one for the hole center location. Optional: You can move the location of the hole 2” toward the front of the stand, away from the motor. This will give your feet more room while pedaling. Some students end up hitting their heals on the stand with the current design. See figure 2 for general cutting pattern.

12”

6” or 8”

1 ½”

8 ¾”

18”3”3”

Figure 1

B

F F

D

A

14.5”

13”

32”

9.5”

15”

16”

Figure 2

9.5”

B

A

B

F F

Remove to reduceweight

Remove to reduceweight

2. Attach the side support structures to the base board (A). See figures 1 and 2 for the correct location and spacing.

a. The most important parts of the mounting is the 13” spacing between the side supports and the holes for the hardware to attach the bike to the stand must be aligned.

b. Once the support structures are in the correct location, and the drilled holes are aligned, attach the side supports to the base (A) using the 1 ¾” screws through the top of the 2x4’s (D). See figure 1. This will secure the locations of the supports so that you can turn the stand upside-down and use more screws to securely attach the base.

3. Assemble and attach the hardware to that will secure the back wheel of the bike to the stand.

a. Locate parts J, K, L, M, N and R. See figure 3. Note: Item N and R on the left hand side of the picture were flipped horizontally accidently in the picture..

b. Attach the hardware to the side supports. The ½” bolt coupler (M) screws onto the end of the ½” 5” long bolt. The ½” conduit coupler (N) then slides over the coupler and the small set screw must be tightened to attach the two. Remove the 2nd set screw on the end so that you can tighten the hose clamp (R) on the end. See figure 4. These hose clamps are required. Without the hose clamps, the conduit couples (N) will break after repeated use of the bike generator.

Figure 3

J

K

L

K

JL

M

N

R R

N

M

G

Figure 4

4”

9.5”

EGG

F F

B B

4. Construct the motor mount stand. This provides a place to mount the motor / generator to the stand. This step requires parts C, E, G, H, I, O, P and Q.

a. Attach the 10 1/8” 2x4 board (E) to both 20” 2x6s (G). Use the 2 ½” screws (I). The 10 1/8” 2x4 (E) should be 9 ½” from the front end of the 2x6s (G) and the back of (E) should be flush with the base board (A). See figure 4. Optional: the back ends of the 2x6s can be cut off at an angle, again to reduce the overall weight. See figure 5.

b. Use the bolts (O), washers (Q) and wing nuts (P) to attach the motor mount to the rest of the stand. It is not critical where the bolts are placed. See figures 1, 4 and 5 for the mounting position of the 2x6s and the bolts.

c. Remove the back wheel of your bike to put the rubber belt around the empty wheel well. The tire and inner tube must first be removed from the rear wheel. Connect the bike to the stand.

d. Using 1” wood screw mount the motor using the motor bracket to the top of board (C) so that the pulley on the motor is sitting in the middle of the board. The motor should be mounted as close to the front of the board as possible. Note: these directions are different than what is shown in figure 5 and you may have to carve out some of the front of board C for the belt to run freely.

e. Now mount the 6”x13” ¾” plywood board (C) with the attached motor using the 1 ¾” screws (I). Place the rubber belt on the pulley during mounting so that you can ensure there will be enough friction between the belt and pulley. Slide the plywood boards back and forth until an ideal amount of friction is found, and screw it down. Figures 5 and 12 show a modification to the described design using a hinge and spring to provide tension on the belt. This modification allows you to take the belt on and off of the pulley without unscrewing the motor mount from the plywood.

Figure 5

G

G

EC

5. Build the front tire mount. The bike generator can be used without this piece, but it allows the bike to be level and provides needed extra support. Students are not always the most gentle when riding or getting on and off the bike. If constructed properly the weight of the bike should be on both the bottom 2x4 supports (S) and the top of the 2x8s (T).

a. In order to cut the 2x8s (T) to the proper height, use uncut 2x8 to separate the 16” 2x4 boards (S). Now place the front tire of the bike on top of the spaced 2x4’s and measure the exact height of the bike’s front forks to the floor. This measured height will be the length you need to cut the 2x8 boards (T).

b. Using the 2 ½” construction screws attach the 2x4s (S) to the freshly cut 2x8s (T), making sure that the front forks of the bike will be able to rest on the top of the 2x8s (T). See figure 6. The horizontal spacing between the 2x8s (T) will may be different for different style bikes.

Figure 6

S

S

T

T

Electronics BoardSee the appendix at the back for prices and links for the materials

Material Size / Length Quantity Part Letter¾” plywood 24”x24” 1 A

Audio Capacitor > 5 Farads 1 (optional) BPower Inverter > 400W continuous 1 C

Kill-a-Watt Meter - 1 (optional) DExtension Cord 1’ 1 (optional) E

Power Strip - 1 (optional) F12V cigarette lighter adapter - 1 (optional) G

Multimeter - 1 (optional) H¼” bolts 1 ½” 1 bag I¼” nuts - 1 bag J

¼” ring terminal connectors (crimp on) - 1 bag K

10 or 12 gauge black and red stranded wire 20’ of each 1 length each L

Diode 1 (optional) MDeep Cycle Marine Battery 80 – 120 Amp∙hr 1 (optional) N

Figure 7

B

H

C D

F

G

E

Figure 8

E

A

N

Electronics Board Construction Notes: (The battery, generator, capacitor and inverter are all connected in parallel.)

If you just want to be able to power typical house hold appliances requiring 120V AC, you at least need an audio capacitor (B) and a power inverter (C).

o The power inverter converts the DC voltage from the generator to 120V AC voltage used by common house hold electronic devices. This is the output from your wall sockets at home.

o The audio capacitor serves to smooth out the output voltage coming from the generator. Your DC output directly from the generator is not very constant due to your inability to keep maintain a constant rotational velocity. This also helps with startup demand for appliances.

¼” bolts, nuts, and terminal ring connectors work well for attaching the wire to the capacitor, the power inverter, and for making connections between wires on the board. Red and black wires are used to color-code the high and low potentials on the electronics board. Some hardware stores sell the wire by the foot, like Lowes. Other stores only sell spools of wire. Paying for it by the foot will end up being less expensive.

If your audio capacitor does not come with a built-in volt meter you can connect a multi-meter (H) in parallel with the generator output and the capacitor so that you can measure the voltage. It is important for the rider to be able to have a real time readout of capacitor voltage since the power inverter (C) will only work between approximately 11V and 15V. If the voltage is getting to low the rider will have to pedal harder / faster and vice-versa. Note: the figure 1 shows a 3rd wire used with the multi-meter so that it is also in series with the battery so that the current going into or out of the battery can be measured.

A “Kill-a-Watt” meter (D) can be purchased to measure the power consumption of devices plugged into the power inverter (C). This is very useful if students want to directly measure the power consumption of any house hold appliance or device. This must be hooked in series with the inverter (C) and the power strip (F). The one foot extension cord (E) is used to connect the meter to the power inverter. The cord plugs into the inverter (C), runs out a hole to the back of the board, and then plugs into the

Figure 9

back of the meter (D) through another hole in the mounting board (A). See figures 7 and 8.

The electronics board can be mounted on a cheap equipment dolly like shown in figure 8 or it can simply be propped up against a nearby wall. If you decide to mount it like shown in figure 8 you will need to place the battery or a heavy object on the bottom so that it will not accidently tip over.

Another nice touch if you are mounting the electronics board on the dolly is to make a shelf for accessories. See figure 8. The shelf and the supports can be made out of the same ¾” plywood as the mounting board (A). A 10 inch deep shelf is enough space for a small or medium TV and a video game system. It is also a great place for a light box. See figure 9. A light box allows students to literally feel the difference between powering an incandescent light bulb and one or several equivalent compact fluorescent. The bulb bases, switches and wire can all be purchased from a local hardware store.

You can power 12V electronic devices directly from the generator / capacitor if you attach a cigarette lighter base (G) in parallel with the generator and capacitor. See figure 7. The diagram shows a switch wired in series with the cigarette lighter adapter to prevent a small LED light in the adapter from draining the battery if it is connected. This is not essential.

Extras

Evenly distribute and attach extra 1kg masses to the spokes of the rear wheel using hose clamps. This will give the spinning wheel some added inertia and will help your rotational speed during operation be closer to constant. The circumferences of the masses determine the size of hose clamps necessary. The used masses for this design required clamps that varied between 1”-1 ¾” and 2 – 2 ¾”. See figures 10 and 11.

If you will be using a battery to store and use energy you will need to put a diode (M) in series with the motor / generator and battery. See figure 12. Failure to do so will allow the battery to directly power the motor / generator and it will cause the pedals to spin backwards!

Figure 10 Figure 11

Figure 12

M

Appendix

Motor. From a scooter, 24V.  If you search for "scooter motor" on google, you'll find a bunch of sites.  I can't find the exact one I used, but this is the same motor: www.scootercatalog.com/electircmotor-e7.html  )  $30-50 plus shipping

Pulley. (from www.electricmotorsite.com )  1-groove, A Belt, 0.5 Bore with a 3" outer diameter.  $10 plus shipping

Belt (from www.Grainger.com).  (V-Belt, Type A.  74” long). $20 plus shipping.

Sleeve Bearing (also called a "press fit bushing").  This is to attach the pulley to the shaft of the motor.  ( www.mcmaster.com ) If you buy the motor recommended above you will want to order a steel press fit drill bushing, inner diameter 5/16” and outer diameter ½” and 1” long.  3-5$ plus shipping

Capacitor. (6F, 24V, "Kole Audio C6D Capacitor”). www.sonicelectronix.com . $80 plus shipping

Safety Note, this is a HUGE capacitor.  When you get it hooked up, it is the most dangerous part of the machine, it can store a whole lot of charge.  This capacitor has a voltage display on it, which is a really nice feature to have on the electronics board.   

Inverter.  We recommend the Cobra CPI 875, 800W DC to AC inverter. It has a nice feature where it beeps when the input voltage gets close to being too low, or too high. www.amazon.com . $40 plus shipping.    

Power Strip. Scrounge around or buy one at your local hardware store.

Digital multi-meter (optional). Can be found at your local hardware store. $10 to $20.

Kill-A-Watt Meter (optional). Can be found at your local hardware store. $40. Short extension cord. 1’ or less. Can be found at your local hardware store. $5-$10. You need this if you choose to use the Kill-A-Watt Meter.

Deep Cycle Marine Battery (optional). Can be found at your local auto parts store. $100-$120.

Diode (optional). You will need this if you decide to store energy in a battery. Without this diode the battery will directly power the electric motor and spin the pedals backwards! Radio Shack sells packs of these diodes for about $5.

Plenty of 1/4" bolts, nuts, and washers for terminals on the electronics board.  1/4 ring terminal connectors (crimp on type).  Enough wire to (I used 12 gauge) to run from the

motor (mounted behind the rear wheel) to the electronics board in front, then a few extra feet to wire things together on your board.  You should be safe if you get about 40 feet total (20' of red, 20' black).  A few twist connectors.