What future for GPS bike computers?
 

Hello all,

With the bike specific GPS units market just developping, do you think we will see more GPS being designed for bike use and that they will eventually replace the standard magnet/sensor technology ?
Is there any patent or technlogical knowledge that prevent brand other than Garmin from launching such products? I asked a couple of makers (Sigma for instance) if they planned to add GPS units to their line and they came up with a negative answer.

I couldn't tell you about any patents. But my company (former, really) did a lot of work on precise automotive location tracking systems, and found that GPS is not accurate enough or consistent enough. We and most other automotive researchers in advanced safety systems used a hybrid of GPS and inertial guidance, usually with a map database with enhanced detail.

Accuracy: commercial or easily available GPS is really only accurate to the 5 or 10 meter neighborhood, depending on the circular error probable. Adding fixed ground GPS transmitters helps a lot, but now we are depending upon new infrastructure. Plus, when you are out training in the mountains, will the signals be available? Generally stationary transmitters are placed to cover urban areas and shorelines.

Consistency: GPS results get better or worse depending on the number of satellites that can be recieved. It tunnels or city business districts ("urban canyons") satellites can be outright blocked. If you need to determine the vertical dimension you need more minimum satellites than if you only need latitude and longitude.

I know that some of these methods are patented.

Map databases have issues, one being cost of licensing the database, say from NavTek. Plus they can have errors, and might not be totally accurate in a less-commonly used dimension, like altitude. Bikes might add some new requirements, like tracking the difference between riding the inner edge of the curve versus the outer edge. Precision tracking systems such as I worked on are stretching to tell you for sure what lane you are in, or distinguishing lane from shoulder.

I could see work being done to resolve some of these issues. There is someplace to go, more room for development. But the magnet/sensor unit is just a part of the inertial navigation sensors that, for high accuracy and consistency, would need to supplement GPS.

I am already using the GPS in my cell phone that is running a little application as a replacement for the regular magnet/sensor computer.

Check these out:

http://www.trimbleoutdoors.com
http://www.sportypal.com
http://bimactive.com

All of these run on cell phones. Bimactive can run in the background which means that I can also answer phone calls, if necessary, or run my turn-by-turn VZNavigator GPS app at the same time. As long as there is cell phone coverage, I have not run into issues with accuracy or consistency.

I can't argue that you are a satisfied customer, and perhaps I'm imagining bike requirements that are more stringent than they need to be. For my automotive application, GPS alone was not adequate.

Have you used it on roads with long tunnels? How about in skyscraper-filled urban areas, like the Chicago Loop, or Manhattan? If you're running a tracking app on top of a turn by turn nav and route guidance system, yes, the real time date you are getting is fine. But my apps were a lot more demanding than that.

If the distances it returned were off, would you know it? How?

Note I'm not saying an app won't run. I am saying 2 things: Maybe I'm wrong about what a bike computer/route guidance/route capture device needs as far as performance, and maybe there isn't really a good way to tell what the performance of your system is. If I was in your shoes, I'd be very happy if it was reliable, and don't have a real-time method of checking performance and calibration.

If I wasn't too cheap right now to upgrade my iPhone to the GPS-enabled one, I'd be using one of those apps, too, and probably overjoyed with it. But I can check the accuracy of my Cateye with a loaded rollout. I would probably not believe such a test with a GPS system, unless it also had a calibrated road pickup.

I use a Garmin Forrunner 305. I have a speed and cadence sensor accessory for it. The speed a cadence sensor uses magnets. The GPS is great because I can upload my ride statistics to the internet. This also allows you to import courses into the Garmin. It is great for monitoring your performance. I have my heart rate, calories, cadence and distance displayed on it.

I also have use a Vetta cycle computer. I use it for my speed, average speed and time. By having both I can see all 7 functions simultaneously. The Garmin has a faster response and is more accurate than the Vetta.

Is this really an issue for a cycling GPS unit in that would someone need it/use it in an area that would have such affected coverage areas? For example, I ride away from my local business district when I go for a ride, not towards it.

I suspect most of the things that disrupt GPS for cars most of the time are going to be urban canyons. But I'm sure that regular canyons can do good work on the GPS as well. The GPS signal is not exactly super-high-power. It gets absorbed. And certain types of broken electronics can act as GPS jammers.

So, it's probably better, in all circumstances, to have more than just the GPS for speed measurement.

OTOH, I tend not to see the cyclecomputer as a criticality-one item. If an aircraft doesn't know how fast it's flying, it can crash. Not the same thing for bikes. :)

Well, aircraft also have airspeed indicators that depend on nothing outside the plane but the air itself. But yeah, if your cycling GPS stops working because you're in a tunnel, well, OK -- no big deal.

I'd say that the Garmin 705 has most of what a GPS for a bike would ever need. There's lots of room for improvement in the device, but they're little/simple things rather than anything revolutionary. I imagine the next versions will be networked with each other and perhaps other devices, perhaps on the Internet, but that seems simple enough.

I don't know about patents, but I hope Garmin doesn't have it all locked down.

The magnet/sensor technology works and works well and does it cheaply. I don't see much of a need to replace it in the future. Even the Garmin 305/705 uses it -- for cadence, and for speed when your GPS isn't working.

I'm using my GPS unit a lot since I live in a national forest west of Glacier National Park and find that Google maps is extremely inaccurate for my area. I've got a Mio C320, which is hacked and running MioPocket. This enables me to use it as a PIM as well as install and run other GPS applications, including OziExplorer's CE-based off road GPS application--Ozi Explorer CE. (I've downloaded USGS's free topo maps for my state to use with Ozi Explorer CE.) I use my GPS enough on my rides that I ordered a bike mount for it. Right now, I have to stop and retrieve the GPS unit from my pannier bags to get my bearings and then re-pack it. I'm looking forward to having it mounted on the handlebars.) So far, I've had no problems acquiring a signal.

Obviously a GPS is not a necessity, but neither is a cycle computer. Both are great to have. My Vetta and my Garmin are both wireless. I don't have those stupid wires snaking around my frame. My Garmin also has a heart rate monitor. If you want to get serious about riding or training a cycle computer and a heart rate monitor are quite useful.

Also the Garmin works well for running or walking.

I'd like to see a small unit (in the size of current bike comps) that uses GPS to determine distance and speed. It might be practical to have the GPS part as a separate, slightly larger unit with it's own batteries. The comp unit should NOT do mapping, just display basic bike comp data (speed, distance, average speed, time etc). This would keep the unit small in size and give it longer battery life.

I think the GPS error margins would be acceptable to me, a magnet based bike comp isn't spot-on accurate either. After all, the product could be used with several bikes with no hardware installations / calibrating necessary, and also when running, xc skiing, kayaking, hiking etc.

From current models, higher end Polars are something like this, but they take a HR/training instructor approach. I'm not sure if that complicates the simple speed/distance logging. Suunto flagship wristop computer has GPS, but it has poor battery life. And all are ridiculously expensive, compared to a bike comp.

Garmins, Magellans etc don't cost so much and fit the bill, except they're bigger than ideal because of the screen size. For most of my riding (commuting) I don't need maps.

--J

If I lived in such an area and wanted to track my rides, I would see it as an issue. Probably the tunnel is less common than the urban canyon in terms of population exposure. I'd not be happy if I had to worry about what roads I had data on and what roads not.

It's much more critical for the automotive safety systems I worked on, true.

The diversity of use cases is huge. My needs and your needs are but small subsets.

If the global GPS system is just used for route guidance nav, fine. But if it's used for ride tracking and capture, maybe not.

Generally I agree about the magnetic sensors. They work, and are now cheap.

I've been using regular bike computers for years and recently thought GPS might be interesting to try. As an experiment, I rigged Magellan Explorist 100 to the handlebars and rode with that for a few days. I found that the speed reading jumped all over the place and the distance was inaccurate (compared to regular bike odometer, Google maps and mapmyride.com). Granted, this is an older GPS receiver, but I was certainly NOT impressed with it for biking. The GPS boxes I use in my car are however sufficiently accurate and very helpful.

GPS may not be a necessity for an urban dweller who rides locally, but it is if you ride off road or in remote areas. (I didn't buy my first GPS unit until I relocated from the east coast to the northern Rockies. I had plenty of fairly up-to-date maps available for the east coast, including the Alexandria drafting company book maps. There's nothing comparable out west.) I'm mainly riding forest roads and off road right now. It's easy to get turned around and lose your bearings. On average, my county, which has a national forest taking up 90 percent of it, has at least one motorist who dies of exposure in the winter due to taking a forest road (usually by mistake) and getting lost. Two years ago, 3 motorists died after getting lost or their vehicles breaking down. (Contrary to the wireless carriers claims of good national coverage, we're also one of the many rural areas in the country that has very little to no cellular coverage. If you're going to vacation in an area like this, don't just pack your cell phone and think you're covered for GPS. Bring a real GPS unit not dependent on a cellular connection for functionality. It may just save your life.) If you're going to go off road, I also suggest that you check out Ozi Explorer CE. You can import maps, including topo maps.

You are probably referring to Garmin Edge units. I have a Garmin Forerunner 305. I can wear it on my wrist or snap it into a holder on my bike. It is only slightly larger than my Vetta.

It is interesting that Garmin is the only player in the bike/GPS market. That may be a case of patents, or simply the size of the market.

Can't see magnetic sensor bike comps gong away. You can still get one with lot's of features quite cheap.

I used my car gps to measure speed in a big parking lot today. it was pretty awkward.

someone told me that gps measures from point to point from space and so if you are climbing or descending it's not measuring speed accurately. gps for speed is only good it your riding on something level.

Plus, the wired versions don't gobble batteries like regular handheld GPS.

Speaking of which, for those of you that do use a GPS app on your cell phone...does that cause the phone's battery to poop out any faster than just using it for talking?

Agreed, and this is true even if you include the wireless regular cyclometers. A GPS requires that you regularly replace or recharge the batteries - usually before each ride if you want to be sure not to have it quit on you. This is in marked contrast to other cyclometers where the battery only needs to be replaced every year or two. With a regular cyclometer I just leave it on the bike and it's almost always ready to go without any special considerations. In contrast I take the GPS off the bike after each ride - partly to download data to my PC, but also to recharge the batteries.

I like to have the navigation features and also the record keeping of exactly where I went and that's why I've been using a GPS in lieu of a cyclometer for the last 11 years. But it's certainly much more convenient to use one of the cheap cyclometers and leave it on the bike semi-permanently.

GPS is less accurate in vertical direction, but I wouldn't say "only good". Compared to what? If you use a traditional bike comp, 3mm difference in tyre diameter results to about 1% error in distance/speed calculation (700C wheel). Changes in tyre pressure can easily result in that kind of difference.

--J

What. While on the bike: Some of us enjoy getting lost.. That is when I make my greatest undiscovered back-country finds. Fads are for yuppies No thanks.

There's an off-brand bike GPS I saw. Also, I think Polar has some GPS units.

Yes.

Polar and Suunto both have GPS units, but they seem to be more geared towards training aid, not just bike comps. I believe Timex used to make one too, but not sure if it's still in production.

--J