Frankenciser - Bike Computer Upgrade to a Vintage Friction Exercise Bike

This is a follow-on to the Frankenciser - Magnetic Resistance Upgrade to a Vintage Friction Exercise Bike.

The mechanical speedometer and digital timer on my 1980’s Panasonic EX-1000 flywheel exercise bike still work fine. The bike is direct drive, no coasting, so cadence is a function of miles-per-hour. Easy enough to figure and build a chart. However, I wanted cadence, time, and miles-per-hour in a nice, easy, digital display. I wanted “modern”.

I looked at a bunch of bike computers and decided on the CatEye Strada Cadence Bike Computer CC-RD200. It had the features I wanted, good reviews, and good reliability feedback.

Putting it together is simple once you figure out how to position the sensors. It is a bit different than the Instructable Add Cadence/Speed/Odometer to Your Spin Bike, mainly with the positioning of the sensors. It seems the gaps are bigger on the Panasonic.

Some Cateye reviewers said that they couldn’t get the sensor and magnet to work with more than a 3 mm gap. The instructions for the bike computer also say not to exceed 3 mm. This install has about 10 mm gaps and works fine. I think it may have to do with correctly aligning the magnet to where the sensor is actually located in each housing and reduced disruption of the magnetic field by using non-magnetic materials as spacers. The sensor is in the middle of the cadence sensor and in the tip of the wheel sensor.

Parts

1 ea - CatEye Strada Cadence Bike Computer CC-RD200

1 ea - 1-1/4 inch dowel (2-1/2 inches long)

1 ea - Self adhesive cable tie base

10 ea - Cable ties, from the kit

2 ea - 12” cable ties, for the cadence sensor and spacer

1 ea - 8” cable tie, for the flywheel magnet

1 ea - Mighty Bright 40516 XtraFlex2 Book Light

Dowels come in “wood”, maybe poplar, and “hardwood”, maybe oak, and either will work for this purpose. They do, however, take stain and paint differently if you are planning on “dressing up” the spacer.

Tools

Cable tie tension gun (see note)

Side cutters (or other cutters)

Saw

Half round file or rasp

Manual, CatEye Strada Cadence Bike Computer CC-RD200 (a PDF is available, search for CATEYE STRADA CADENCE ENG)

Note: I have a no-name version of a “Gardner Bender CTT-45 Cable Tie Tensioning Tool” that I bought cheaply. It served its purpose but I wished I had spent a few dollars more for a more consistent tool. During this project, I bought a Klein Tools 86570 Nylon Tie Tensioning Tool and am pleased with it.

Note: Just the usual admonition to use safety equipment and to be careful of hot, sharp, or rotating parts and equipment.

Step 1: Cadence Magnet, Sensor, and Spacer

Preparation

1. The sensors on a street or road bike are attached within inches of each other, on the crank and rear tire. On a flywheel exercise bike, they are separated by feet. Fortunately, the wire used on the Cateye is “zip wire” that allows the joined wire to be separated.

2. Hold a wire (not the sensor) in each hand and pull slowly and smoothly. You will need about 28 inches of free wire for the cadence sensor.

3. Read the manual. Setting it up is not "intuitive".

Cadence magnet, sensor, and spacer

You will need to have the display attached to check the functionality before you lock the parts down.

1. The cadence sensor and magnet are located on the side of the exercise bike opposite the chain. However, there is too much distance from the pedal crank arm to the seat tube for the sensor to detect the magnet. A spacer has to be made.

2. Cut a spacer (1-1/4 inch diameter dowel) to 2-1/2 inches long. File a concave channel about 3/4 inches wide along the long dimension of the dowel with a half-round file or rasp.

3. If you want to dress it up with paint, stain, or a wrap, now is the time.

4. Attach the spacer and cadence sensor to the seat tube, just above the bottom bracket, with two long cable ties. Pull the cable ties snug but not tight.

5. Attach the magnet to the inside of the crank arm with one cable tie so it passes over the middle of the sensor. Pull the cable tie snug but not tight.

6. Set the display to Cadence and slowly rotate the crank to confirm that the sensor and magnet works. Adjust the position of the sensor or magnet if it doesn’t.

7. When it works consistently, tighten the cable ties. Cut off the tails squarely at the locking head. You don’t want pointy ends sticking out that can poke or scratch.

8. Attach the cadence wire from the seat tube up to the head tube using the kit’s ties. Make sure you are not going to catch the wire while riding or getting on or off the exercise bike.

Note: Some reviews said that they couldn’t get the sensor and magnet to work at more than 3 mm but I didn’t have that problem.

Step 2: Wheel Sensor, Magnet, and Spacer

Wheel sensor, magnet, and spacer

You will need to have the display attached to check the functionality before you lock the parts down.

1. The wheel sensor and magnet are located on the side of the exercise bike opposite the chain. However, there is too much distance from the fork tube to the flywheel for the sensor to detect the magnet. A spacer has to be made.

2. Attach the speed sensor to the inside of the fork tube with two cable ties. Pull the cable ties snug but not tight.

3. Attach a self adhesive cable tie base to the side of the flywheel in a position corresponding to the tip of the sensor.

4. Slip a tie through the magnet base and the adhesive base. Pull the cable to form a ring so the magnet is close to the sensor without hitting the sensor.

5. Set the display to Miles per Hour and slowly rotate the crank to confirm that the sensor and magnet works. Adjust the position of the sensor if it doesn’t.

6. When it works consistently, tighten the cable ties. Cut off the tails squarely at the locking head. You don’t want pointy ends sticking out that can poke or scratch.

7. Attach the flywheel wire to the fork tube up to the head tube. Make sure you are not going to catch the wire while riding or getting on or off the exercise bike.

Finish

1. Slide the display off and mount the bracket to the handlebars. The bracket does a surprisingly good job of clamping.

2. Neatly gather and corral the excess sensor wire and find an out of the way place to tuck the bundle, like under the “instrument panel”.

3. Program the display per the manual:

3.1. Wheel selection

3.2. Wheel size in mm – measure the diameter and calculate the circumference (3.1416 x the diameter). Just for nostalgia, I set it so that it equaled the mechanical speedometer.

3.3. Clock setting

3.4. Total distance manual entry

3.5. Speed unit

4. Wrap some Velcro around the handlebar and attach the Mighty Bright 40516 XtraFlex2 Book Light. Adjust it so it lights up the display without reflecting off the display or the chrome.

You are ready to ride.