My wireless Sunding 548C cycle computer works well, except that if I travel at over about 35 kph (22 mph), the speed indicator reverts to zero and there is no accumulation on the odometer, until my speed comes down below about 35 kph again, wherupon it kicks back in.

Any thoughts?

My thought: https://bellbikestuff.com/pdfs/111741WirelessManual.pdf but even better https://www.amazon.com/Bell-Dashboar.../dp/B01IGU9XIK

I have had zero luck with cheap wireless off-brand computers, and life is too short to struggle with them.

It uses a spoke magnet for the speed calculation?

It's less than $10. wow, very inexpensive.

Try adjusting the magnet position slightly up or down the spoke. And get the sensor quite close to the magnet. It might not trigger correctly at the higher speeds.

Thanks, I'll give it some trial-and-error tests

It occurred to me that my short post looked flippant or snobbish, but let me correct that. I do all of the repairs on my electronics, computers, tv's, everything I've bought since about 1980, and I do tend to try inexpensive stuff so I would fix it if I could. But I've tried a couple of cheap wireless speedometers, with no success. . What I mean by "toss it" is that based on those, the probability that it will work right for more than a month or two, times the $15 to replace it, should be valued less than the time spent messing with. Change the batteries if you have them, move the head unit to a different location, if that doesn't work I recommend an inexpensive wired Bell or Schwinn which are every bit as good for basic functions as more expensive ones.

I bought my dad an expensive wireless speedometer for his birthday from bontrager, and even that didn't work. First ride down to the bike shop and back (a few miles at most) it said he had gone 60 miles. (And mph reading seemed reasonable while riding it was setup).

I just go wired now. Suppose that won't work for the "clean bikes lines" aesthetic but it's just a lack of hassle.

The battery finally died on one of my wired speedometers after about 10 years and I had to replace it...that's all the maintenance I've had to do and it's worked flawlessly otherwise.

I don't know why they can't get around to putting decent wireless into speedometers (they have it working with cell phones, wifi, etc) but they don't.

I've never tried a wireless bike computer, but I've used several cheap Chinese wired computers. Some sell for as little as $3. They've worked flawlessly for me.

I've added a rare earth magnet to the el-cheapo you tend to get with speed sensors and had improved results. They're pretty cheap on amazon, just find the size you need.