So I already bought and installed a Garmin 520, but i'm still mulling over the option of repurposing a smartphone to use as a bike computer.

The phone in mind is a 4.5" Motorola E with GPS/GLONASS tracking and Bluetooth 4.0 (BTLE). Costs ~100$ new. Pair with HR Strap, high-quality mount (Quadlock), and BTLE Spd/Cad sensors, comes out to roughly same price.

Primary motivation are:
*Use Strava as primary platform, so why go through intermediate channel like Garmin software
*Direct integration of sensors
*More choices of monitoring apps
*Garmin known to be buggy, slow with fixes, etc
*REAL navigation, real usable screen
*No dependency on phone for connectivity
*Have all the Live Segments and etc built in (add cheap prepaid data SIM to phone)

Don't use Garmin Vector, so no need for Garmin's "analytics".
Not as long battery life, but unless its a 10 hour ride with screen constant on is a non-issue.
Not as weatherproof, but easily solved with simple cover, and not planning on riding in a thunderstorm either.

Only thing I see as a con is that going across multiple bikes, I'd like quick detachable non-magnetic Spd/Cad sensor that Garmin has...but thats only available with Ant+ (Although I dont really need CAD, just HR)
Also not entirely sure if BTLE supports multiple concurrent devices

Anything else I'm missing?

Battery life will be your drawback. Short rides (2-3 hours) you should be fine.

People use phones as bike computers because they're cheaper; at the same price I wouldn't go for an inferior solution. A Garmin has a decent battery, if you ride more than a couple hours at a time with the screen on you'll need to buy a separate battery for your phone; a bike computer is waterproof, you'll have to buy a case for your phone if you might ever get caught in the rain, and that will interfere with the touch screen and possibly the battery, a bike computer doesn't have a monthly software charge, etc. Popsicle sticks and bubble gum.

This

And this.

Plus you won't be able to see the screen in most light situations.

What Garmin offers is hard to beat, all things considered.

What will you use for the bluetooth speed sensor? Have you tried the app to see what the display looks like in daylight?

I use an old Samsung S3 as bike computer currently. I'm planning on getting the Garmin 520 soon as the phone has been very frustrating to use. With screen on and live segments the battery barely lasts 2 hours. It actually looses GPS connection from time to time as well. Suddenly when riding in high speed it can auto-pause for 10 seconds or so. The cover I have for it also makes it quite difficult to use the touch display when it rains.

All in all I can't wait to get a Garmin.

This looks intriguing, hacking a kindle (with it's easy to read e-ink display) to display the speed sensor readings. https://hackaday.com/2015/08/21/easy...r/#more-165794 but storing the data for Strava or other analysis would be more involved.

So you've never owned a Garmin?

But yes, dedicated bike computer over phone for me. And yes, I own a Garmin.

I use my phone as my computer. I'm completely satisfied with it, but I don't check my screen very often.

I adapted a battery that fits in my steerer tube for extra long rides, but I don't ever need it.

Having a dedicated garmin would probably be less hassle, but I like my phone being where I can see it since my kids are often with a sitter or with friends when I ride.

The biggest battery drain is the display when it's constantly on. I wish Strava or some other smartphone apps would have a display mode that's like on for a few seconds for every X minutes or something. If you are a serious cyclist and doing time trials, yeah, sure, you need your numbers in front you to manage your efforts. But for us recreational cyclists, I don't need to look at my number constantly for normal riding.

I picked up a Wahoo RFLKT+ to mirror from my phone. So far so good, but I have noticed that riding next to high tension power lines tends to interfere with the BTLE signal between it and my phone. All I had to do was move the phone from my middle jersey pocket to the right pocket. That said, I'm still on the fence over another Garmin (had the 500, broken in my accident). I need more time with the RFLKT to come to any sort of conclusion.

I just picked up a 520 and love, will never go back.
What i used to use was my regular phone, in my jersey pocket with MMR/Strava running to record my data and a cheap Cat Eye so I can see speed and cadence in real time. It worked great, but starting a new job soon with on call so the notifications feature of the 520 sealed the deal for me.

To be clear, Garmins can be buggy, but people generally make too much out of it. In general they work really well, that's why so many cyclists use them. An example is my watch does auto-lap by distance (eg every 5 miles) but not by location, so when I do hill repeats I have to press the lap button myself.

I have an Edge 800 and a Fenix 3 watch. I don't have to pay a monthly fee to use software on either of them, the way you would for a lot of the more useful stuff you'd use on a phone if you didn't want a Garmin. I don't understand your laughter. Are you paying for Training Peaks or something?

I use a refurbished Sony Xperia Active (purchased for $100) and the IpBike app. Phone has an Ant+ radio. Before that I was using my HTC One M7 which also have an Ant+ radio but required your to root and get S-Off, plus the Ant+ Enabler app. The IpBike app can do everything that Garmin has to offer except for turn-by-turn (map and route shown only) and Strava segments. The problem you'll get into with BT Smart star only networks is that it limits the number of sensors that can be used simultaneously to one, see https://www.thisisant.com/developer/...arison#386_tab. If you need track more than one matrix (e.g. HR, speed, and cadence) you are out of luck without a bridge. One thing to note if you are using a phone, keep it water tight. I had to purchase the Sony because my HTC didn't like my sweat and developed a personality issue with the digitizer.

I get about 4-5 hours on the Sony phone without a Sim card and with the a sleeping screen my HTC can go over 6 (had problems with Sony not recording data when screen goes to sleep and haven't tried after the fix was pushed out). On long rides I just hook it up to a USB batter pack/charger. Ant+ Enabler can activate the Ant+ radio in Nexus 5, Nexus 6, Nexus10, HTC One (M7), LG G2, and Samsung S4 Active phones. Ant+ radio in Samsung Galaxy S3 are turn on by default.

Honestly if I was to do it over again, I would have bite the bullet and bought a Garmin. I only went this route because I had an Ant+ able phone and wanted to root it anyways.

Just using a phone/app will relegate you to the land of outlandish elevation & speed errors.

Ah, my apologies. I read your comment as "doesn't have a monthly software change." I thought you were saying that the Garmin would never have troublesome firmware updates like the phone would.

The thing with Garmin is that they mess up the simplest little things, and sometimes it might not even be a feature you use. There was an issue for several revisions where following courses reduced your overall distance by 10%. I just didn't use courses. But the latest issue is having trouble syncing for downloads to your phone. Yeah, I kinda need that one to work...

Somebody told me he was using a $5/month phone app as their cycling computer. He has a few other premium apps that round out his bike software suite. And the guy told me it was cheaper than a Garmin. I've had my Edge for 5 years, really can't see any reason to replace it. At $5/month I'd have spent $300 by now to rent processing time on my phone, add in the other apps and it's more expensive than a Garmin.

But yeah sometimes their QA is lacking. My Fenix 3 used to reset my MaxHR and FTP on software updates about half the time. Fortunately they've fixed that.