# GPS or Cycle Computer



## drag13honda (Aug 23, 2015)

Hello all. I have a newer bike that I am looking to add something to in order to track basic information from rides. I come from a time of just using basic cycle computers, many of which were even wired. There have been a lot of technological advances made in this area, and I am basically trying to decide if I should just go with a basic cycle computer or if I would be better served with a GPS unit with a wheel sensor? I'd love to hear some opinions on which is better and why.

Some basic GPS questions I have would be:

Is GPS w/ wheel sensor going to be as accurate as just the basic non GPS cycle computer? And vise versa.

With a GPS unit w/ wheel sensor, if you happen to not have a GPS signal where you are riding, would you still record the data and will it be as accurate?

Thanks for the help.


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## OldMike (Apr 30, 2020)

I'm in the same boat as you (old school wired Odometer w/magnetic sensor).
I know from riding with a friend who uses a GPS that both it and my old Odometer were within 98% of each other.
Close enough for me.

I just bought this ($30 USD) as I feel it's way easier (just mount and go). I plan on chartging it once a week.


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## 834905 (Mar 8, 2018)

The Garmin Edge series computers are stellar. I’ve been using the same Edge 520 for years and never had a single issue with it. Holding GPS signal has only been an issue maybe twice, both times in canyons on remote rides. The old wheel sensor units like Cat Eye are a thing of the past imo.


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## J.B. Weld (Aug 13, 2012)

Get a cycling gps, you won't regret it.


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## mack_turtle (Jan 6, 2009)

I have been using a GPS of some sort (phone, then watch, then a computer) for several years. love it.
most GPS units are not super accurate. for the _basic_ information about approximately where you rode, how fast, elevation, etc, it's fine for an enthusiast. they can be made more accurate by simply adding a wheel sensor.

the main advantage for me is tracking where I rode to remember certain rides, to share your experiences with friends on Strava and such, and —most importantly — being able to preload a route on a map so you can follow it and _not get lost_! I can ride someplace I have never been and just follow trail turns if I draw a route on a mapping program (there are a bunch of these that are free or require an inexpensive subscription), or borrow a GPX file from someone who has done the route before. I can glance down at my stem and see trails and roads and a line to follow without digging my phone out of my pocket every few minutes. (not a fan of putting a huge phone on the handlebar, where it will drain the battery completely in a short time and risk falling off and shattering.)


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## abeckstead (Feb 29, 2012)

There are apps for smartphones which provide stats that will please most riders. The most popular is Strava.

Some key advantages of a GPS bike computer is if it has an altimeter, so that your elevation gains are recorded more accurately. You can add external sensors: wheel, cadence, heart rate, power meter etc and display more data or analyze it later. I like the Wahoo GPS computers.


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## TrailGoat (Sep 6, 2016)

to get started, just use your phone. it wont cost you anything and you can see if it is sufficient for you. you can download free apps, and Strava is probably the most popular. It displays your ride stats/summary in a pretty nice format too.


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## RickBullottaPA (Mar 4, 2015)

drag13honda said:


> Hello all. I have a newer bike that I am looking to add something to in order to track basic information from rides. I come from a time of just using basic cycle computers, many of which were even wired. There have been a lot of technological advances made in this area, and I am basically trying to decide if I should just go with a basic cycle computer or if I would be better served with a GPS unit with a wheel sensor? I'd love to hear some opinions on which is better and why.
> 
> Some basic GPS questions I have would be:
> 
> ...


Your smartphone and a QuadLock bike mount. Truly the best of all worlds. And far, far better apps than any dedicated GPS unit.


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## J.B. Weld (Aug 13, 2012)

RickBullottaPA said:


> Your smartphone and a QuadLock bike mount. Truly the best of all worlds. And far, far better apps than any dedicated GPS unit.



Depends how you use it I guess, a Garmin head unit is perfect for my needs but I don't use maps. Don't want a big ol phone on my handlebars.


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## mtnbkrmike (Mar 26, 2015)

I use both. My Edge 830 was a great purchase. It does so many things really well. Except maps. I still pull out my phone and use TrailForks. No big deal. Love them both.

As for a cycle computer? Yeah, no.


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## RickBullottaPA (Mar 4, 2015)

J.B. Weld said:


> Depends how you use it I guess, a Garmin head unit is perfect for my needs but I don't use maps. Don't want a big ol phone on my handlebars.


I really didn't want one either - until I tried it with the QuadLock. Trailforks on an iPhone is fantastic when hitting up new riding areas, and I don't need to keep stopping to look at/interact with a map (which was required with my Garmin Edge) and in landscape mode it's actually quite unobtrusive.


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## RickBullottaPA (Mar 4, 2015)

mtnbkrmike said:


> I use both. My Edge 830 was a great purchase. It does so many things really well. Except maps. I still pull out my phone and use TrailForks. No big deal. Love them both.
> 
> As for a cycle computer? Yeah, no.


The irony that a garmin sucks at maps... ;-)


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## mtnbkrmike (Mar 26, 2015)

RickBullottaPA said:


> The irony that a garmin sucks at maps... ;-)


It may very well be user error on my part, but I haven’t been able to figure out how to use mapping very well on my Edge. My phone is dead simple. I carry my phone anyway and pull it out from time to time for pics and video, so no big deal. If I had to figure it out on my Edge, I would.

To be clear though, my Edge stands among the top 3 purchases I made in 2021. And despite COVID, I managed to buy a lot of very cool things.


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## jetdog9 (Jul 12, 2007)

Do a search for DC Rainmaker and you'll find a site with all the info you need about GPS computers. 

I was happy for years on an Edge 520, recently updated to newer 530 and very happy again. 

GPS by itself is usually pretty accurate. GPS + properly calibrated speed sensor even better.


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## 834905 (Mar 8, 2018)

I agree that the maps aren't great. I use the Training Routes for bikepacking and longer routes... definitely hard to follow sometimes, but they work.


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## mtnbkrmike (Mar 26, 2015)

jetdog9 said:


> …GPS by itself is usually pretty accurate. GPS + properly calibrated speed sensor even better.


Agreed. I got the MTB bundle. The rubber case/sleeve, mount, speed/distance sensor and (especially) the remote, were all immediately used and have proven to be of great benefit/value.

Advice to those buying any Edge - get the MTB bundle. You will not regret it.


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## North woods gal (Apr 26, 2021)

At one point I had so many bikes that setting up each bike with its own computer was getting nuts. I switched the Garmin Edge 130, but without the wheels sensor at first and my stats were way off from the bike computers. Added in a wheel sensor and problem solved.


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## RickBullottaPA (Mar 4, 2015)

mtnbkrmike said:


> It may very well be user error on my part, but I haven’t been able to figure out how to use mapping very well on my Edge. My phone is dead simple. I carry my phone anyway and pull it out from time to time for pics and video, so no big deal. If I had to figure it out on my Edge, I would.
> 
> To be clear though, my Edge stands among the top 3 purchases I made in 2021. And despite COVID, I managed to buy a lot of very cool things.


If its any consolation, it's not you. 

The mapping and nav experience on the Edge(s) my wife and I have owned is awful (don't even get me started on the Fenix as a map/nav device), the screen is too small and "noisy", and the interaction with buttons/touchscreen is really poorly designed for mountain biking. Thus far, Trailforks has been the best I've experienced. It's not perfect, and could use a couple UI tweaks (bigger touch targets for soft buttons, alternatives to pinch/stretch, etc) but the overall experience and the quality/completeness of trail maps is excellent.

We sold our Edge 830 and 1030 and invested in QuadLock mounts for our MTBs and gravel bikes (and I also use their desk stand/charger) and have been really happy. We've both crashed a couple times and the mount(s) and phone(s) are still good as new.


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## Harold (Dec 23, 2003)

drag13honda said:


> Hello all. I have a newer bike that I am looking to add something to in order to track basic information from rides. I come from a time of just using basic cycle computers, many of which were even wired. There have been a lot of technological advances made in this area, and I am basically trying to decide if I should just go with a basic cycle computer or if I would be better served with a GPS unit with a wheel sensor? I'd love to hear some opinions on which is better and why.
> 
> Some basic GPS questions I have would be:
> 
> ...


basic cyclocomputers were always effectively disposable to me. Failure rate after a few years was always high.

Garmins have been far more reliable for me (at least, when Garmin doesn't mess the product up with a bad firmware update, which happened to me on an Edge 705).

The best thing a GPS-enabled computer lets you do over a basic cyclocomputer is save data from each individual ride. You can associate photos with these files, which is fun for trip reports/memory lane sorts of stuff. The way the GPS data is stored lets you associate all kinds of other data that can be helpful for training purposes or mapping. I lean far more towards the mapping side than the training side.

IMO, a wheel sensor combined with your GPS computer is pretty essential for mtb purposes. Every turn gets cut a little short with GPS distance calculations. It's just the way it works. The sharper those turns are, the faster you take them, and the more of them that get packed into a given area, the more error in distance calculations you're going to get. A properly calibrated wheel sensor will override those GPS-derived distance calculations and give you much improved accuracy. The quality of your calibration will determine how much more accurate. These computers are much smarter than basic cyclocomputers and will often have an "auto" calibration mode that your cyclocomputer didn't have. It's easier to use, but it's not as accurate.

You're almost never going to completely lack a GPS signal in a given spot where you're riding. Exceptions I've encountered have been indoor bike parks like Ray's MTB and the old KY Mega Caverns underground bike park. The wheel sensor will still report distance in such cases because the GPS signal won't be penetrating through. You're best off in cases like that to just turn the GPS receiver off since you're doing an "indoor" ride. That mode was originally meant for use when you're on a trainer. But it works just as well when you're actually riding your bike indoors.

What you're most likely to encounter is the loss of accuracy from turns that I've already described. The next possibility is that you might have momentary loss of signal. Maybe you're down in a really deep canyon/valley with thick forest. Maybe you're doing a road ride and you ride through a tunnel. It's pretty much unheard of to be riding outside and never receive enough of a GPS signal that you don't get a position fix. I haven't encountered that situation since before 2000 when the government turned off selective availability.

When you lose GPS signal momentarily like that, the track can do all sorts of wacky stuff. Just before losing it completely and right after faintly picking it up again, it'll wander all over and could add a LOT of extra distance. With a wheel sensor, the track will still look wacky on the map, but the distances will still read correctly. If you're using the data for mapping purposes, you can manually edit the junk data out.

I HAVE had the problem where I traveled a large distance from home and my GPS took a very, very long time to get a position fix since it had to figure out new satellite positions. That's kindof inherent in how GPS receivers work. Travel a long distance or not turn the device on for a very long time and it has to receive extra data about which satellites are going to be visible and where it should find them. If you expect that sort of thing to occur, you can prep for it and let it do that work somewhere open where it's easy to receive those signals. Not starting that process until you're at the trailhead deep in the woods is going to make it take longer.

Phone tracking apps can work okay, sometimes. But there are limitations. Phones are massive these days and mounting one to your bars can be really irritating. The mount is also likely to be less secure. The phone will be more exposed to being hit by stuff. I've had to replace a couple Garmins after crashes. That's a whole lot less of a hassle than if that had been my phone. Phone hardware is extremely variable, also. The GPS hardware might be very good or very bad. You generally aren't going to know until you've used the GPS hardware in your phone for a bit and really pushed its limits. When it's bad, it can be _very_ bad. Phones also have highly variable battery life. Some do pretty well. Others can be absolutely awful. Phone screens can be iffy under damp, sweaty conditions. I've had some that were impossible to use under those conditions. My current one isn't so bad, but it's not great, either. My Garmin is an Edge 520 with physical buttons because of this. Don't have that option with phones. There are some sensors that work with phones, but not all apps can use them. So if you want to use any sensors while riding, you will have a limited selection of apps you can use with them. With a dedicated GPS computer, you'll have a LOT more flexibility with sensors.


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## mtnbkrmike (Mar 26, 2015)

RickBullottaPA said:


> If its any consolation, it's not you.
> 
> The mapping and nav experience on the Edge(s) my wife and I have owned is awful (don't even get me started on the Fenix as a map/nav device), the screen is too small and "noisy", and the interaction with buttons/touchscreen is really poorly designed for mountain biking. Thus far, Trailforks has been the best I've experienced. It's not perfect, and could use a couple UI tweaks (bigger touch targets for soft buttons, alternatives to pinch/stretch, etc) but the overall experience and the quality/completeness of trail maps is excellent.
> 
> We sold our Edge 830 and 1030 and invested in QuadLock mounts for our MTBs and gravel bikes (and I also use their desk stand/charger) and have been really happy. We've both crashed a couple times and the mount(s) and phone(s) are still good as new.


I love my Edge for about 25 things apart from mapping. It does so many things well.

Before you ask me to list them, I don’t know how many of those things are not available on my phone. But for me, using my phone for anything other than TrailForks was 100% unsatisfying.

Could one get by using their phone alone? Of course. One could get by using nothing. But for me, I love my Edge and this is going on a year of ownership now - long past the honeymoon phase.

I still screw around with things while sipping a beer in the evening and watching a movie. It’s been a lot of fun for me, and well worth the $500 I paid for the MTB bundle.


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## fftfk (Nov 26, 2020)

One additional item is battery life. Dedicated GPS will have a much longer battery life than your phone for recording long rides. I've never felt I needed a gps as my rides are all about 2 hours or less but I have a friend who routinely does 3 to 4 hours and his phone will die on them.


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## Cary (Dec 29, 2003)

For just tracking with no live info, a phone with Strava (can use a heart rate monitor also) works well. I went with a Garmin 130 then 830 after a while as I wanted to see live HR, elevation, and mileage, but don’t want to chance destroying a phone on the bars. The 130 does the foregoing well, but is worthless as a gps. The 830 is a far better display and easier to see with a better GPS. The GPS on these are great for tracking and when you preload directions, but others not very good. I download maps to my phone ahead of time and have them on hand if I need to references a “map” or change route mid course.


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## Harold (Dec 23, 2003)

Cary said:


> The 130 does the foregoing well, but is worthless as a gps


how so? first I've heard of that.


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## Cary (Dec 29, 2003)

Harold said:


> how so? first I've heard of that.


130 has breadcrumb only and no real maps. If you get at all off track, good luck figuring out where you got off and how to get back on. It also has about 1/2 the battery life of the 5 series. It is really a cycle computer with gps tracking and very crude routing.


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## Harold (Dec 23, 2003)

Cary said:


> 130 has breadcrumb only and no real maps. If you get at all off track, good luck figuring out where you got off and how to get back on. It also has about 1/2 the battery life of the 5 series. It is really a cycle computer with gps tracking and very crude routing.


Oh, I see.

Yeah, it's really just designed to record or display data. And that's fine if that's what you want. It's mostly what I do with my GPS devices anymore, anyway.

The most important thing I expect from a GPS these days is accurate track recording. Does the map it records accurately depict the trails I rode? That should be true for all GPS computers, whether they're intended to just record/display data (like the 130), or do more mapping. I thought _that_ was the kind of thing you were referring to. Anyone buying an Edge 130 should not expect much navigation from the device. There are ways to manage that by loading pre-programmed routes with the turn notifications programmed into them. But that's all you're going to get.

My older Edge 520 is only marginally more advanced than the 130. It navigates the same way as the 130. Folks figured out how to put maps on it, even though Garmin didn't really intend for that to be a function for the device. I put maps on it because I can. Most of the time it doesn't matter that I've done that. I mostly don't need maps for the trails I ride locally, unless I'm riding something that's not regularly in my rotation. And when I do use maps, I heavily prefer paper ones. I really only use digital ones when I need them in a pinch and I don't have a good paper one.


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## mtnbkrmike (Mar 26, 2015)

Again, it may very well be user error on my part but my attempts to use my 830 for maps while riding has been a complete fail. 100% crap compared to my iPhone and TrailForks. LOVE the 830 for so many different reasons, but mapping is definitely not one of them.

For some reason, my display is super dark now. I changed my "activity profile" from "Mountain" to "Fat Bike", and I can't see a damn thing on the screen anymore. I have it set to auto brightness, 2 minute backlight timeout and auto colour mode. Any ideas?


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## Harold (Dec 23, 2003)

mtnbkrmike said:


> Again, it may very well be user error on my part but my attempts to use my 830 for maps while riding has been a complete fail. 100% crap compared to my iPhone and TrailForks. LOVE the 830 for so many different reasons, but mapping is definitely not one of them.
> 
> For some reason, my display is super dark now. I changed my "activity profile" from "Mountain" to "Fat Bike", and I can't see a damn thing on the screen anymore. I have it set to auto brightness, 2 minute backlight timeout and auto colour mode. Any ideas?


those auto modes are probably what did it. I know on my phone the auto brightness often interferes with visibility under certain conditions.

you have to get used to how a real GPS handles navigation if you're used to phone apps. there are legitimate reasons they operate the way they do, and it's for more advanced backcountry nav purposes, not the lowest-common-denominator (which is why most phone apps navigate the way they do).

dedicated GPS receivers have a learning curve. and not all of that learning curve is specific to using the device. some of it is basic navigation theory. most phone apps make an effort to be more user-friendly, but in so doing, they skip the navigation theory background knowledge. this is both a benefit and a detriment.


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## mtnbkrmike (Mar 26, 2015)

Harold said:


> those auto modes are probably what did it. I know on my phone the auto brightness often interferes with visibility under certain conditions.
> 
> you have to get used to how a real GPS handles navigation if you're used to phone apps. there are legitimate reasons they operate the way they do, and it's for more advanced backcountry nav purposes, not the lowest-common-denominator (which is why most phone apps navigate the way they do).
> 
> dedicated GPS receivers have a learning curve. and not all of that learning curve is specific to using the device. some of it is basic navigation theory. most phone apps make an effort to be more user-friendly, but in so doing, they skip the navigation theory background knowledge. this is both a benefit and a detriment.


Thanks Harold.

The biggest deterrent to using my 830 for mapping is that my iPhone 13 Max screen is what? 6 times bigger? Likely closer to 8x bigger? Maybe I should have thrown down on the 1030 and not the 830.

Plus the TrailForks mapping makes my 830 mapping look like something from the Atari days.


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## Harold (Dec 23, 2003)

mtnbkrmike said:


> Thanks Harold.
> 
> The biggest deterrent to using my 830 for mapping is that my iPhone 13 Max screen is what? 6 times bigger? Maybe I should have thrown down on the 1030 and not the 830.


Meh, I don't want a screen that huge on my bars. But even then, a screen that size isn't _that_ much better compared to how much of the terrain you can see on a paper map.

This is part of the reason why I prefer the paper map for navigation when I can get it. When I use my phone to supplement my navigation, I still only use it for fairly quick reference stuff. Detailed nav work gets the paper map every time.

I think the advantage of the small computer for navigation purposes is the ability for it to give turn notifications right on the bars, to give you the ability to quickly scan for things nearby like intersections, stream crossings, or how much farther until you reach the top of the climb you're currently on. If you need more than that, then you don't want that thing mounted on the bars.

If you have navigation properly set up with turn notifications, the computer gives you a cue sheet screen that tells you the distance to each turn, also.


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## mtnbkrmike (Mar 26, 2015)

Harold said:


> Meh, I don't want a screen that huge on my bars. But even then, a screen that size isn't _that_ much better compared to how much of the terrain you can see on a paper map.
> 
> This is part of the reason why I prefer the paper map for navigation when I can get it. When I use my phone to supplement my navigation, I still only use it for fairly quick reference stuff. Detailed nav work gets the paper map every time.
> 
> ...


Yes. I clearly need to put some more effort into it. 

Waiting for it to warm up today to hit the trails tomorrow and Monday. I will spend part of today trying to get up the curve. if you know of any decent YouTube videos to help me with the Edge mapping function (or whatever you call the mid-ride TrailForks equivalent), I'd appreciate hearing from you. Thanks.


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## Harold (Dec 23, 2003)

mtnbkrmike said:


> Yes. I clearly need to put some more effort into it.
> 
> Waiting for it to warm up today to hit the trails tomorrow and Monday. I will spend part of today trying to get up the curve. if you know of any decent YouTube videos to help me with the Edge mapping function (or whatever you call the mid-ride TrailForks equivalent), I'd appreciate hearing from you. Thanks.


I'm not sure I know what you're referring to with "mid-ride TrailForks equivalent" mapping? I've only ever looked at TF on my phone to see a map. And since they went to a subscription, I don't even do that. I only use the website anymore.

I simply don't use a device to make mid-ride changes to a ride. If I need to change a ride from what I've previously planned, then I dip into my own navigation skills. I've been burned by on-device routing in the past, so I avoid it now.


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## mtnbkrmike (Mar 26, 2015)

Harold said:


> I'm not sure I know what you're referring to with "mid-ride TrailForks equivalent" mapping? I've only ever looked at TF on my phone to see a map. And since they went to a subscription, I don't even do that. I only use the website anymore.
> 
> I simply don't use a device to make mid-ride changes to a ride. If I need to change a ride from what I've previously planned, then I dip into my own navigation skills. I've been burned by on-device routing in the past, so I avoid it now.


Primarily, I meant pulling out my phone at junctions, to make sure I stay on the route I want to stay on. Which is what I use TF for. It works beautifully.

Also to see where I am on a particular trail, and how much is left. Other similar things too.


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## Harold (Dec 23, 2003)

mtnbkrmike said:


> Primarily, I meant pulling out my phone at junctions, to make sure I stay on the route I want to stay on. Which is what I use TF for. It works beautifully.
> 
> Also to see where I am on a particular trail, and how much is left. Other similar things too.


You can do those things with the Garmin. But they involve programming the route you want to ride beforehand and then loading it onto the device.

I have no idea if there are any youtube videos on the subject. 

But RideWithGPS has some very good tutorials. Ride With GPS Help


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## drag13honda (Aug 23, 2015)

So from the sounds of it, it sounds like there is very little concern with not getting a good GPS signal unless deep in the wilderness in deep valleys and/or lots of heavy tree cover? If I'm understanding it right, even if you don't have a gps signal the wheel sensor will still record your ride details (short of tracking your physical location), right? So even at worst case scenario you should still log your distances, times, etc.?

Sorry for the basic questions, just want to make sure I have a good understanding of what to expect before making a purchase.

Thank you.


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## Harold (Dec 23, 2003)

drag13honda said:


> So from the sounds of it, it sounds like there is very little concern with not getting a good GPS signal unless deep in the wilderness in deep valleys and/or lots of heavy tree cover? If I'm understanding it right, even if you don't have a gps signal the wheel sensor will still record your ride details (short of tracking your physical location), right? So even at worst case scenario you should still log your distances, times, etc.?
> 
> Sorry for the basic questions, just want to make sure I have a good understanding of what to expect before making a purchase.
> 
> Thank you.


tree cover is much less of an issue with gps reception than terrain. It used to be more problematic, though. Newer chipsets (for processing data) are the primary reason for the improvement. Tree cover rarely blocks GPS signals outright. They typically cause it to scatter and reflect and more powerful, modern chipsets are better able to process these scattered signals and make something out of them. Older chipsets couldn't.

Of course, that depends on having a good gps antenna, too, and that's another area where dedicated receivers do better than phones. Phones share too much of their internal components between functions, and the gps antenna is smaller. So even though phones have powerful gps chipsets, their smaller antennas (at least in some cases - but it's kinda impossible to know because this is not a specification that phone manufacturers advertise) reduce their quality.

Your GPS computer on its own will always be recording activity timing as long as you can turn it on and push the start/stop button. So without a GPS signal, it's just a stopwatch. If you start adding additional sensors, even without GPS signal, you can start to do more stuff. If you add a wheel sensor, you are able to measure distance in addition to the time data that the head unit is recording. And once you have those two, you can calculate speed. It doesn't matter if the GPS receiver is turned off (as you would do if you were riding on a stationary trainer), or if you've lost the signal. Heart rate, power, cadence, and barometric altimeter sensors all also work independently from the GPS, so if you have these sensors, you are also collecting data from them whether the GPS is operational or not.

Fascinatingly, you can use your computer and a programmed workout activity to go backwards and control a "smart" trainer such as a Wahoo Kickr to simulate a previously recorded ride. With good data, your previously recorded ride will also have information about the terrain that the trainer and associated accessories can simulate. The trainer will adjust resistance based on the recorded slope. The Kickr Climb will adjust the angle of the bike to simulate changes in slope. The Kickr Headwind can help to simulate speed by adjusting fan speed.


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## Jayem (Jul 16, 2005)

There's also a ton more satellites, even the regular GPS constellation has more than the 1990s...if your GPS uses WAAS, it's even more, if you're GPS uses GLONASS and GALILEO, even more and this is very common these days. Terrain masking is a lot more rare these days in general. We are a bit lucky here at high latitudes where we "see" satellites on the horizon for longer, so our sat availability is actually better than mid-latitudes, but in reality, this is better everywhere as compared to when GPS first started coming out on consumer devices.


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## Harold (Dec 23, 2003)

Jayem said:


> There's also a ton more satellites, even the regular GPS constellation has more than the 1990s...if your GPS uses WAAS, it's even more, if you're GPS uses GLONASS and GALILEO, even more and this is very common these days. Terrain masking is a lot more rare these days in general. We are a bit lucky here at high latitudes where we "see" satellites on the horizon for longer, so our sat availability is actually better than mid-latitudes, but in reality, this is better everywhere as compared to when GPS first started coming out on consumer devices.


that, too. But even my older devices that only have access to the GPS constellation (and WAAS) have very reliable reception under trees. the early-mid aughts seemed to be a watershed time period when the hardware could process multipath errors (the kinds of reflection and scattering you get from forest canopy) MUCH better than the hardware that was available for a few years after selective availability was turned off.

And of course the availability of extra satellites and even more hardware improvements made everything work even better.

My understanding is that the GLONASS constellation is especially useful for folks in upper latitudes, since Russia designed it to be optimized over their own territory. The closer to the equator you get, the less helpful it is compared to GPS because GPS works better over those latitudes. Though I've also read that GLONASS gives faster acquisition times than GPS, but slightly less accurate positioning. So even for folks elsewhere, if you can get GLONASS satellites for signal acquisition speed and GPS satellites for positional accuracy, you're taking advantage of both worlds. I've encountered less consumer hardware that uses GALILEO in addition to GPS and GLONASS, so I'm not sure what it's best at.


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## Jayem (Jul 16, 2005)

Harold said:


> My understanding is that the GLONASS constellation is especially useful for folks in upper latitudes, since Russia designed it to be optimized over their own territory. The closer to the equator you get, the less helpful it is compared to GPS because GPS works better over those latitudes. Though I've also read that GLONASS gives faster acquisition times than GPS, but slightly less accurate positioning. So even for folks elsewhere, if you can get GLONASS satellites for signal acquisition speed and GPS satellites for positional accuracy, you're taking advantage of both worlds. I've encountered less consumer hardware that uses GALILEO in addition to GPS and GLONASS, so I'm not sure what it's best at.


Regular US GPS works better at high latitudes, we "see" the satellites for longer before they are masked by the earth due to their orbits, as compared to mid-latitudes. This essentially gives us more in view at any one time. The system was originally for flinging missiles over the North Pole, so it makes sense. What you say about GLONASS might be true, although I'd think they would want world-wild capability from their system too.


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## Harold (Dec 23, 2003)

Jayem said:


> Regular US GPS works better at high latitudes, we "see" the satellites for longer before they are masked by the earth due to their orbits, as compared to mid-latitudes. This essentially gives us more in view at any one time. The system was originally for flinging missiles over the North Pole, so it makes sense. What you say about GLONASS might be true, although I'd think they would want world-wild capability from their system too.


seeing the satellites for longer doesn't necessarily mean optimal function for ground nav.

for a precise location fix, one component that's pretty important is the satellite arrangement in the sky. if they're all clustered in one small area, satellite geometry is poor and your location accuracy will suffer. the farther north you are, the more satellites you're going to find in the southern sky relative your position, and the harder it will be to get really good satellite geometry.

with more satellites in the sky, it probably works better now than it did a decade or more ago, but I'd wager that satellite geometry gets poorer and is reflected in lower accuracy the farther north you go.


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## Jayem (Jul 16, 2005)

Harold said:


> seeing the satellites for longer doesn't necessarily mean optimal function for ground nav.
> 
> for a precise location fix, one component that's pretty important is the satellite arrangement in the sky. if they're all clustered in one small area, satellite geometry is poor and your location accuracy will suffer. the farther north you are, the more satellites you're going to find in the southern sky relative your position, and the harder it will be to get really good satellite geometry.
> 
> with more satellites in the sky, it probably works better now than it did a decade or more ago, but I'd wager that satellite geometry gets poorer and is reflected in lower accuracy the farther north you go.


I have seen graphs and diagrams on availability and had long discussions about the use of the system in these latitudes. I don't know if the number took into account accuracy at the same time, but availability was flat out better here at our latitudes when the constellation was the minimum 23 or whatever satellites. I don't think we are nearly far enough North to get the "all satellites on the equator" effect you might be thinking of. Rules were originally drafted for the use of GPS in aviation in Alaska because it was one of the first test-beds for much of the technology. Unfortunately, as the technology has evolved, many of these rules have not been subsequently updated. A real close grouping of sats together might be a problem, but I suspect it's not a problem at all when the sats are all in one hemisphere relative to your location. The system works by pseudoranging, differential math to solve for one time that accounts for the speed-of-light delays in the atomic sat time and message. I'm sure you know, but much of the public doesn't, the sattelites are whizzing about super fast and they aren't actually sending their "position", they are sending the universal atomic time, one thing that can be held constant in the constellation. I would suspect as long as the sats aren't grouped "together", it doesn't make as much difference if they are say, all on one side of you. As an example, Deadhorse, aka Prudhoe Bay, almost our furthest North location, has an RNAV GPS LPV approach that gets the airplane down to 200' above the runway, same as a precision Instrument Landing System approach. Most LPV approaches are 250', but the deciding factor of if they go down to 200' isn't the GPS precision, unless there was some crazy interference of other limitation, it's the terrain and airport limitations, the airport runway markings, lighting, etc. If that infrastructure is good enough, they take it down to 200' and 1/2 mile of visibility, required to land. In most cases, the autopilot flies down to that 200, or lower with some special authorizations. So again, there isn't any difference here between these and the approaches down in the lower 48, as far as lacking the precision capability that has to work and be reliable.


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## cmg (Mar 13, 2012)

Garmin 830 is the absolute hammer.
I love I can plan routes on my phone and send straight to the 830, takes a little learning but then its easy, even easier on the computer.
I travel a lot, so l often take one of my bikes, generating a random route in an area lm not familiar with is awesome. Especially when you select distance and ride type. This is done in 5 mins and bang lm off riding a route in an area l dont know. Having said that it has stung me a few times, but only in MTB mode, all road routes have been good.
The battery life of the 830 is also great.

but it is a Garmin........which means the menu setup is weird and makes no sense, and every update changes your settings. Im used to all tjis as lve been in the Garmin ecosystem for about 25yrs, but for new users it must be annoying.


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## Harold (Dec 23, 2003)

land nav is a good bit different than aviation. different angle to the horizon, terrain is a larger factor.

satellite geometry isn't an all-or-nothing prospect, either. there's a lot of variation as everything is moving relative to everything else. where I have lived, I usually have satellites visible scattered all across the sky, but I've had occasions where only a few were visible in one direction. sometimes it might mean that it takes longer for the receiver to resolve the signals into a position because the satellites are close together. sometimes it means that more satellites are needed to get geometry sufficient to resolve a location at all.

the terrain is usually a factor when I've had these things happen. 

the reason GLONASS is a little better farther north is simply because Russia has more territory farther north and they wanted good accuracy over their own terrain. sure, it's a global system, but it's optimized for their own terrain and uses. 

This is a useful tool to tell you a little bit about what's going on with the satellites.

Trimble GNSS Planning 

This is what's visible in my area right now.









And here's a spot by Anchorage.










Yeah, definitely more satellites, but lots of those are around the horizon. Easy for terrain to block them when they're really low, and for the distance the signal must travel through the atmosphere, for atmospheric distortion. But if you pick them up, you can get good geometry. Not much directly overhead, though (less affected by terrain). And most of the ones that are, are GLONASS birds. In my area, I get a combination of satellites near the horizon, but good spacing and some coverage directly overhead. A small area towards the north without any satellites. This is the sort of thing I'm referring to.


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## NordieBoy (Sep 26, 2004)

This is what I see...


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## Harold (Dec 23, 2003)

NordieBoy said:


> This is what I see...


fascinating that tight cluster of BeiDou birds to your west.


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## NordieBoy (Sep 26, 2004)

Harold said:


> fascinating that tight cluster of BeiDou birds to your west.


Almost like they weren't just navigation satellites...


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## eugenenine (Aug 2, 2018)

I'm wondering the same myself now. I have an old Garmin eTrex Legend HCx that I bought in 2007. I use it for hiking as well so I carry it on my Camelbak strap rather than a bike mount. But compared to phones now a days its feeling big and bulky and while I like that I can just swap out AA's its soft on always drains them before I go to use it so I have to remember to drop in a fresh pair before use. I want something a little smaller that I can leave plugged in to always be charged and ready.


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## drag13honda (Aug 23, 2015)

I know on the older cycle computers you had a trip odometer and a regular odometer for total miles. I know the trip odometer has basically been replaced by the fact that the GPS tracks the information from each ride you go on, but do the GPS computers still have a "total miles" tracker? Just curious if that was quickly available to look at or if you would look at wherever you store your ride data to calculate monthly/yearly/total miles and such?


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## eugenenine (Aug 2, 2018)

Some do. My old Garmin has a total that I can reset. I copy off the .gpx files and add them up though so I don't really use the total.


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