Spoke sensor for bicycle

You can mitigate the amplitude problem somewhat by parallelling a capacitor, but that won't boost the voltage at low speed, it just puts a hard limit on the high-speed output.

Wiegand needs to be re-magnetised to the opposite polarity to produce a pulse, but two magnets are probably not a deal breaker if one is acceptable.

Forty years or so ago I was doing some work for either Austin Rover or British Leyland, can't remember which world-leading high-quality British car manufacturer, there were so many.

Anyway, a test car they used had something like that - an optical device looking at the road to accurately measure speed. IIRC it was very expensive.

I have a feeling it was something to do with diffraction gratings and prisms.

There's a fun effect that's sometimes used in sensors for things like paper handlers: if you shine a laser on a rough surface, the speckle pattern moves exactly twice as fast as the surface. This turns out to be a fairly deep consequence of the law of reflection.

Cheers

Phil Hobbs

You're talking about devices that sell on Aliexpress for $1.29.

If you're a halfway serious cyclist, there are computers that measure cadence, pedal rotations per minute, again with a magnet attached to the pedals, in addition to the usual RPM/ speed and total distance. Looks like the reed relays have been abandoned in favor of hall effect or the giant magntoresistance technology, dunno which. The packages are way too flat to house a relay. The little magnets and their housing look unchanged from the reed relay days. Plotting the actual route has always been a big deal for road cyclists, so I imagine GPS is used for that in the high end units- but they still need magnets and sensors for cadence measurement, and probably a backup for wheel RPM.

The so-called industrial designers look first at the kind of functionality and form the prospective users will most likely want, and only then hand the design off to nuts and bolts people capable of making a physical product. You'll be hard pressed to improve upon or innovate existing products.

In article <t8d3mh$hc9$ snipped-for-privacy@dont-email.me, Dimiter_Popoff snipped-for-privacy@tgi-sci.com wrote: <SNIP>

Everybody uses a bike here, including elderly with a heart condition. In the Netherlands electric bikes are quite popular. They are bought by people to occasionally take a slope easier, or go slightly faster. They are eminently practical and handle as normal bikes with benefits. At least 10 % of new bikes sold are electric (probably more).

Groetjes Albert

Are they as expensive as in the US where they start at 1600 USD and go to more than twice that? I watched a video by a man in his '60s that was very informative. He liked the bike but pointed out some of the disadvantages. Since they're a hot commodity they tend to get stolen. The best U-lock or chain is no obstacle for someone with a portable angle grinder. The batteries are also vulnerable, at around $500. They do have a lock but according to him a couple of sharp blows with spring it.

He'd had knee problems and hadn't ridden a bicycle in 30 years. Between that and the higher center of gravity he'd fallen twice. He did a survey of the ebike forums and found that was common. My thought was they may attract people who have little experience on two wheels. That's concerning since they seem to fall into two categories, 20 mph motors with more torque and 27 mph motors wound for a little less torque but more speed.

in EU regular electric bikes are max 250W and no electric aid above 25km/h (~16mph) you can get one from ~800€ and up

here there also a trail with the so called "speed pedelec", they are more like a moped. max speed 45km/h it needs to be registered and have insurance and you have to wear a helmet and have a moped or car license

The specs are all over the place. I even saw one that claimed 500w, 250w nominal in Europe. Somehow I'm suspicious of a 750w claim by Bafang. There was a flood of Chinese scooters for a while, some claiming 150cc's which it turned out was the oil volume. It was actually a 50cc engine.

Some trails here have signs posted banning any ebikes but they are traditional mountain bike trails, not the paved multiuse trails in town. I have a couple of pedal powered bicycles, and three motorcycles so I'm not anti-bike but I'm not comfortable sharing a pedal bike / pedestrian trail with something capable of 45 km/h. They would be better suited for city streets with bike lanes where they could keep up with traffic in many cases.

unless it is type approved, max 250W, no aid above 25km/h it is not legal on public roads if stopped by police you'll get a fine, possibly confiscated the bike and in an accident you'll have problems with insurance

New electric bikes start well under 1000 euro's, second hand still less. The batteries are a concern, but one will live with that. Stolen bicycles is a concern, but there are electronic ways to counter that.

Concerning spoke detectors.

If the material is stainless, the conclusion that it has no magnetic properties is not warranted. Check with a magnet. My 30 year old race bike has stainless spokes, but they are magnetic.

Yesterday I walked home from my restaurant, inspecting 200 bicycles. From those approximately half have galvanised spokes. No need to inspect those, they are magnetic. From the other bikes there were few we expected to have non magnetic spokes. I suspected especially those that are black and thin. These are not carbon fiber, but they are slightly magnetic, sufficiently to detect I guess.

The bottom line suggests that the news is good if you want to market a device that works on spokes. However I found something strange. My friend has magnetic spokes front, non-magnetic at the rear. Another friend has slightly magnetic spokes... in the even positions right and non-magnetics spokes in the odd positions. Apparently there are batches of spokes and they switch in the middle of spoking a wheel, and the magnetic properties are apparently of no concern.

Groetjes Albert

Bafang have a 750W crank-mount motor, and a 1000W one. If they're efficient enough they don't have to dissipate much of that, of course.

They can be road-legal if the controller limits the output to 250W. You might need to prove that however, especially if the bike can unlock full power for off-road use.

Remember there are also electric powered scooter and bikes, that are considered motor vehicles, and fall under the same regulations as gas powered, e.g. registration and insurance.

Groetjes Albert