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Budget bike computer

Old 09-29-18, 08:05 PM
  #26  
HerrKaLeun
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Originally Posted by noglider
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.
What app/phone are you using? My experience with GPS speed is it is pretty accurate and doesn't jump around (must have a stabilizing algorithm).
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.
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Old 09-30-18, 10:54 AM
  #27  
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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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Old 09-30-18, 11:57 AM
  #28  
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Originally Posted by noglider
@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.
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.
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Old 09-30-18, 12:52 PM
  #29  
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Originally Posted by HerrKaLeun
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.
There are lots of fender benders, but congestion is high, therefore speeds are low, so it might not prove to be a place for lots of injuries and deaths. I'm not sure how it stacks up. We're trying to improve it, and we have a "Vision Zero" program going on, and I'm not sure if it's working. Cycling is overall safer than being in a car, counterintuitively.

But congestion has gotten a lot worse in recent years. It was always crazy, but it's super insane now.
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Old 10-16-18, 10:56 PM
  #30  
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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?
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Old 10-17-18, 08:28 AM
  #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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Old 10-17-18, 01:07 PM
  #32  
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Originally Posted by amazinmets73
Are bike navigation units susceptible to cold-weather failure or are they hard-wearing?
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.
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Old 10-17-18, 08:57 PM
  #33  
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Originally Posted by amazinmets73
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
Well you should certainly check out the Garmin Edge 500, available on eBay for under $60. It provides everything you've discussed and more: navigation, cadence, speed, distance, elevation, slope, heart rate, power, and temperature. While some may criticize this aging device for its lack of wifi and bluetooth, workarounds exist. Plus, it's fairly easy to service yourself.

Last edited by sierrabob; 10-17-18 at 08:58 PM. Reason: typo
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