Update on my Helmet Light (Reduced Weight Design)

This is my newest helmet light for safety while commuting. It’s similar to my previous one but was designed to be lighter.

It was powered by 3 rechargeable AA batteries. The unused battery slot was used for the circuitry. It used AMC7135 LED drivers so that 3 AA batteries could be used instead of 4 for stability.

The front light was warm white for preserving night vision and had a narrow beam pattern.

The rear light was wide-angle and installed on a self-levelling mount to make it consistently visible.

It weighed around 175g. With less weight on the helmet, it should be easier on the neck and back. It’s possible to go even lighter by using 3 AAA batteries instead, but you’ll need to recharge them more often.

The light was programmed to have four settings in total. It has two settings for being seen during the day, and two for seeing at night. On its lowest setting, it lasts around 40 hours, and on its highest setting, it lasts approximately 6 hours which I think is reasonable.

Here are some pictures of the older helmet light. It used 2 18650 cells and had more LEDs. It weighed about 350g, about twice as heavy as the newest version!

Do you have any suggestions for improvements? If so, please share by commenting below!

Minoura M80 Trainer’s Power Curve at its Maximum Resistance Setting

This chart was made using LibreOffice Calc. The power was measured at different speeds. There was a big gap between the last two points because a high power output was required even though I used the minimum resistance to do the test.

Since it’s linear, you can use a speedometer to estimate your power. You should set the wheel size so that the numbers are close to those in the chart. This is useful if you don’t have a power meter.

Screenshot 2017-10-23 16.47.45.png

Screenshot 2018-03-10 18.27.13

Comparing Different Trainer Selections in TrainerRoad

In TrainerRoad, it’s possible to use virtual power even though if your trainer isn’t supported.

I tested the wattage readings from the selections of Minoura’s trainers at different resistance settings. The speed was around 25 kph and the cadence around 53 RPM. The Minoura M80 trainer was used at the lowest resistance.

Minoura M50/M80/MAG850L

  • Level 1: 53W at 25.0 kph and 53 RPM
  • Level 2: 105W at 25.1 kph and 53 RPM
  • Level 3: 128W at 24.9 kph and 53 RPM
  • Level 4: 146W at 24.9 kph and 53 RPM
  • Level 5: 199W at 25.1 kph and 53 RPM

Minoura 850

  • Level 5: 206W at 25.4 kph and 53 RPM
  • Level 6: 218W at 24.9 kph and 53 RPM

Minoura M80-R/M70-R/B60

Level 0: 121W at 24.9 kph and 53 RPM
Level 1: 143W at 25.0 kph and 53 RPM
Level 2: 161W at 25.2 kph and 53 RPM
Level 3: 185W at 25.1 kph and 53 RPM
Level 4: 194W at 25.0 kph and 53 RPM
Level 5: 206W at 25.1 kph and 53 RPM
Level 6: 218W at 25.0 kph and 53 RPM

The highest settings seemed to match.

I also tested virtual power for my trainer at 46.6 kph and 83 RPM. The power reading was 466W.