Budget bike computer
#26
Senior Member
Calculating speed from GPS has its own problems. Some computers and phone apps use both GPS and sensors, and this combination improves accuracy.
My app was set to use a small sampling period for displaying speed. As a result, the speed it displayed went up and down wildly, showing speeds I know I wasn't hitting, both too high and too low. I increased the sample period to 50 seconds, and that solved that problem, but now I don't know how fast I've been going for the last 15 seconds. It's too bad. I strongly suspect that when I end the ride, software on the server recalculates speed from all the data points I've provided, because it looks about as accurate as possible. But one problem which can't be fixed is that I ride in NYC where there are many tall and dense buildings. The buildings create reflections, and it shows me zigzagging through buildings and onto the river, which I am definitely not doing. The bigger the deviation, the higher the incorrect speed. It has even shown me to make bursts of speed up to 50 mph while on flat ground. Because these bursts are short, they probably don't throw off my average too much, but max speed becomes a useless metric.
My app was set to use a small sampling period for displaying speed. As a result, the speed it displayed went up and down wildly, showing speeds I know I wasn't hitting, both too high and too low. I increased the sample period to 50 seconds, and that solved that problem, but now I don't know how fast I've been going for the last 15 seconds. It's too bad. I strongly suspect that when I end the ride, software on the server recalculates speed from all the data points I've provided, because it looks about as accurate as possible. But one problem which can't be fixed is that I ride in NYC where there are many tall and dense buildings. The buildings create reflections, and it shows me zigzagging through buildings and onto the river, which I am definitely not doing. The bigger the deviation, the higher the incorrect speed. It has even shown me to make bursts of speed up to 50 mph while on flat ground. Because these bursts are short, they probably don't throw off my average too much, but max speed becomes a useless metric.
On my old phone it missed some parts of the route and just assumed a straight line when it re-connected to GPS, that happened hiking in the forest. but with new phones this wasn't a problem.
similar problems with old phones in big cities driving a car where it assumed I'm some hundred feet elsewhere. but with new phones the problem is minimal.
My maximum speed (on Strava and Samsung Health app) is never higher than i think it was.
#27
aka Tom Reingold
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@HerrKaLeun, I'm using an iPhone 6S and ridewithgps. Everyone in Manhattan has this problem with all GPS devices. The reflections are everywhere. It's like living in a giant house of mirrors.
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
#28
Senior Member
@HerrKaLeun, I'm using an iPhone 6S and ridewithgps. Everyone in Manhattan has this problem with all GPS devices. The reflections are everywhere. It's like living in a giant house of mirrors.
BTW, I was in NYC in 1998 as pedestrian and subway user and what I recall from traffic it must be hazardous to drive a car, and more so riding a bike.
#29
aka Tom Reingold
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Yep, very vertical canyons made of steel screw up radio signals. i agree for that situation a wheel rpm based sensor will be better.
BTW, I was in NYC in 1998 as pedestrian and subway user and what I recall from traffic it must be hazardous to drive a car, and more so riding a bike.
BTW, I was in NYC in 1998 as pedestrian and subway user and what I recall from traffic it must be hazardous to drive a car, and more so riding a bike.
But congestion has gotten a lot worse in recent years. It was always crazy, but it's super insane now.
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
#30
Full Member
Thread Starter
Something I have failed to take into consideration: Smartphones are not designed for cold weather use and will shut-down if exposed to cold. I had this issue on my last ride.
Are bike navigation units susceptible to cold-weather failure or are they hard-wearing?
Are bike navigation units susceptible to cold-weather failure or are they hard-wearing?
#31
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Where are you, @amazinmets73? My phone hasn't shut down in the cold. I'm in New York.
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
#32
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I cannot tell about full-blown navigation units, but this is certainly an issue within basic bike computers. As a rule, screens of cheap Chinese units fade out in the cold. Better units, in particular Sigmas I cling to, work fine (at least down to -25C). Because of bad experiences any item that needs to work in the cold on a bike goes now first into the freezer before I mount it on the bike.
#33
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Went out for a spin today. Locked in bike navigation in the maps app on my smartphone, threw it in my jersey pocket and put on a pair of headphones. Easy peasy.
So it seems I'm set as far as navigation. Just looking for speed, mileage, and possibly cadence. Anyone have any options for $60 or less? Much appreciated
So it seems I'm set as far as navigation. Just looking for speed, mileage, and possibly cadence. Anyone have any options for $60 or less? Much appreciated
Last edited by sierrabob; 10-17-18 at 08:58 PM. Reason: typo
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