# Garmin 500 vs powertap computer unit



## simplyhankk (Jan 30, 2008)

There's not a whole lot of specific info on this yet so I thought I'd ask. 

For those of you who have used Garmin Edge 500 and Powertap cpu unit, 

What does the Garmin has that the PT unit doesn't have? 
What does the PT unit have the Garmin doesn't have? 

Not sure if there are enough of good reasons for me to give up the PT head unit for the Garmin. I'm newb in the power world. Garmin seems much more comprehensive, and from the impressions I got PT unit is very reliable. 

Thanks for any input


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## framesti (Jan 26, 2009)

I wanted to also, is Garmin 705 much better than 500? Just color display?


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## simplyhankk (Jan 30, 2008)

garmin 705 has navigation/mapping. 
500 doesn't.


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## ericm979 (Jun 26, 2005)

Garmin has a lot more data, and it's configureable on three screens. PT's LYC has what it has, which is not a lot.

You can RT the Garmin's FM for all the details. But most of the things I use on the Garmin that wern't on the LYC are more bike computer related (i.e. elevation gain). The LYC is fine for power info, but that's all it does.

I've had the Garmin lock up when I hit the lap button but that's been fixed with the latest firmware. That firmware has been totally reliable.


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## raspaaa (Apr 8, 2009)

Workouts (added in firmware 2.2) and virtual partner. (i.e. race 
againest previous rides). 
Altitude/gradient and temperature tracking.


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## Sonomasnap (Feb 10, 2010)

If you are serious about training you need power data period. And PT has cadence, HR, speed, etc... Who cares about maps?


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## Mahatma Kane (Oct 25, 2005)

On either unit, are you able to immediately view the power output of a just completed interval to compare intervals in a set? And I think I read something about how these 2 units (Garmin 500 vs PT head) update the power readout differently or read the output of the Powertap hub in different ways from each other - or something like that. Does anybody have the details on this?


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## ericm979 (Jun 26, 2005)

Sonomasnap said:


> If you are serious about training you need power data period. And PT has cadence, HR, speed, etc... Who cares about maps?



The Garmin 500 doesn't have maps. And how exactly can more data hurt?


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## Sonomasnap (Feb 10, 2010)

My bad. Misread. Yes the Garmin head unit is much nicer to pair with your PT. I use the 705. I have ridden with both on the bike just to compare and I think the PT head unit responds a little quicker to changes in power output but at the end of the day the Garmin is a better head unit.


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## drew2002 (Sep 7, 2008)

From reading other posts here, main disadvantage of the 500 vs. PT CPU is data loss and software bugs, which is significant, but I think that the trade-off of having more display parameters is worth while, provided the extra $$$ doesn't hurt. Also, not sure about the user interface on the Garmin not having owned one, but the PT CPU's is pretty lame, unless you're one of those people who can set all of their digital watch functions without cursing or reading the manual!


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## ukbloke (Sep 1, 2007)

Mahatma Kane said:


> On either unit, are you able to immediately view the power output of a just completed interval to compare intervals in a set?


On the Edge 500, you can display the power output of the current lap in around half a dozen different ways including power averaged from the beginning of the lap until now. When you complete the lap that field will have the power for the whole lap, then when you push the lap button it resets for the next lap. The Edge 305 had data fields for "last lap" but the Edge 500 does not. So not ideal but workable if you can remember the last lap power.

I'm not sure about the PT as I never use its lap features. I can never remember which button combinations to press.



> And I think I read something about how these 2 units (Garmin 500 vs PT head) update the power readout differently or read the output of the Powertap hub in different ways from each other - or something like that. Does anybody have the details on this?


You have to be careful to set up the treatment of zero power on both units the same for average numbers. "Include zeroes for power" is strongly recommended.

Edge 500 attempts to do "every second" recording when using a power-meter. However, it does drop samples so you do not get every second output in the FIT file. Some people have observed discrepancies from data point to data point for the same activity comparing the 2 head units. Neither is supposed to be smoothing the data so this is harder to explain. It may be that the ANT+ signals from the PowerTap are not arriving synchronized to the Edge's clock, and that the Edge is doing some interpolation to coerce the PowerTap signals to its timing. This would tend to reduce instantaneous peaks which is what some users have reported. This might be a big effect on "1 second power" (which is not a useful measure anyway), but gets averaged away for "5 second power". In summary, they are close enough for almost all practical purposes. 

If you want GPS data you should get the Edge 500 (or maybe 705 or 800). If you want customizable screens and a nice head unit, consider the Joule too. If you just want basic cycling computer functions plus power in a traditional bike computer unit with 100% reliability, get the yellow PowerTap CPU.


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## simplyhankk (Jan 30, 2008)

When the Garmin 500 first came out, it had a lot of bug issues and users were complaining about dropping ride/interval data, and other weird things. 

But then Garmins has come out with firmware upgrades (firmware 2.2?) and that has apparently fixed a lot of those issues and have made the 500 much more reliable and some new features (%FTP). Plus, it has altitude, virtual partner, and it displays a lot more information on the screen than a PT headunit. From the limited research I've done, Garmin seems to be improving the Edge 500. 

Well, I guess in comparison, the PT cpu would be like a tried and true Honda Civic...plain, simple and reliable, and the Garmin would be something like a Merc or BMW. 

I'm leaning toward Garmin..


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## kbiker3111 (Nov 7, 2006)

Isn't the Garmin cheaper than the PT?


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## simplyhankk (Jan 30, 2008)

kbiker3111 said:


> Isn't the Garmin cheaper than the PT?



Well, if you are talking about "value"...then yes. 

PT unit is now overpriced for what it does. Garmin can do a whole lot more with $50ish more and now is more reliable than when it was new


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## ukbloke (Sep 1, 2007)

simplyhankk said:


> From the limited research I've done, Garmin seems to be improving the Edge 500.


Sure, if you define "improving" as fixing all the bugs that they should have found during product test prior to launch to make the device behave as documented as opposed to adding new features. Admittedly, one additional feature that they did add was the virtual partner feature which I guess didn't make the cut in time for the launch. There have probably been other minor feature adds which I've neglected to mention. But, in general, the point remains that most of the firmware changes have been bug fixes (eg. recent fixes for device freezes and corrupt activity data).

But with my experiences with firmware 2.4, I think the Edge 500 is finally ready for prime time.


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## raspaaa (Apr 8, 2009)

ukbloke said:


> But with my experiences with firmware 2.4, I think the Edge 500 is finally ready for prime time.



Apple continues to have new OS updates to improve the iPhone, don't they?  

Your first hand experience is valuable, as users like myself don't have experience and can only read what's posted on the web and speculate. With an ANT+ hub/powermeter compatible Garmin has opened up another door. I look forward to using mine. 
Without power the Edge500 already seems like a competent piece.


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## ukbloke (Sep 1, 2007)

raspaaa said:


> Apple continues to have new OS updates to improve the iPhone, don't they?


Yes, it is unfortunately becoming more common place to ship the product before it is done. Apparently Santa Claus just won't wait for QA testing to complete or for production firmware to be available!

Nonetheless, we can still b1tch about it on the internet and hope that they will mend their ways. Garmin are serial repeat offenders on this so I think the criticism is warranted. As I keep on saying, every new Garmin cycle computer comes with free membership to their field beta test program. I'd be happy for them to prove me wrong with the new Edge 800. Actually, if they send me a free one I'll happily search for their bugs!


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## simplyhankk (Jan 30, 2008)

Dude, your Bike Telemetry gig is cool.


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## Alex_Simmons/RST (Jan 12, 2008)

simplyhankk said:


> What does the PT unit have the Garmin doesn't have?


An ability to validate the calibration / accuracy of the power meter. An inability to do that is a deal breaker. 

If I really wanted a Garmin for its other features, I would still have an LYC for this one vital function.


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## simplyhankk (Jan 30, 2008)

Alex_Simmons/RST said:


> An ability to validate the calibration / accuracy of the power meter. An inability to do that is a deal breaker.
> 
> If I really wanted a Garmin for its other features, I would still have an LYC for this one vital function.



You can't zero the torque on the Garmin? That sounds odd with all the things it can do.


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## ukbloke (Sep 1, 2007)

simplyhankk said:


> You can't zero the torque on the Garmin? That sounds odd with all the things it can do.


You can zero it, but you can't see real-time torque information for checking torque calibration (eg. with weights hung from the pedals).


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## ukbloke (Sep 1, 2007)

simplyhankk said:


> Dude, your Bike Telemetry gig is cool.


Thanks, that's appreciated! It is taking a while to turn it into a product, but we're getting there.


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## simplyhankk (Jan 30, 2008)

ukbloke said:


> You can zero it, but you can't see real-time torque information for checking torque calibration (eg. with weights hung from the pedals).


Well...how inaccurate does that make the Garmin then? Are there any ways to 'avoid' that (zero while not on the bike?) 

Finally there's another thing make the Garmin inferior to LYC..


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## Alex_Simmons/RST (Jan 12, 2008)

ukbloke said:


> You can zero it, but you can't see real-time torque information for checking torque calibration (eg. with weights hung from the pedals).


Correct. I'm not talking about setting the torque zero. 

I'm talking about validating the power meter is actually accurate, which is the one thing every power meter user should do.


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## Alex_Simmons/RST (Jan 12, 2008)

simplyhankk said:


> Well...how inaccurate does that make the Garmin then? Are there any ways to 'avoid' that (zero while not on the bike?)
> 
> Finally there's another thing make the Garmin inferior to LYC..


It's not a matter of the Garmin being inaccurate. It's whether the head unit computer displays the information necessary to determine if the power meter is accurate.

If the power meter is inaccurate, both the Garmin and LYC will display/record inaccurate data.


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## simplyhankk (Jan 30, 2008)

Ok, I'm novice at this. So how often should you do this, and how would you be able to do it with the Garmin? 
I guess this is when people send it their SRMs for calibration?...


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## ukbloke (Sep 1, 2007)

simplyhankk said:


> Ok, I'm novice at this. So how often should you do this, and how would you be able to do it with the Garmin?
> I guess this is when people send it their SRMs for calibration?...


People who hang out on the wattage forum might do torque tests on a regular basis. Those in the real world ... not so much. You can google for "powertap torque test" to find the procedure. I presume you can do a similar test with an SRM. In either case if your measurements and math don't match the reading within the defined error range, you send the unit back for factory calibration.


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## Alex_Simmons/RST (Jan 12, 2008)

simplyhankk said:


> Ok, I'm novice at this. So how often should you do this, and how would you be able to do it with the Garmin?


When you first install it, doing a calibration check is a really good idea. 

Thereafter, you check whenever you suspect something might be up (usually you have a good sense after a while if the numbers are a bit weird) and maybe annually or six monthly.

Powertaps are generally pretty good out of the box (provided you do a zero) but getting one out of spec is not unheard of and having a torque tube go can also happen sometimes, so it pays to be sure.

It's also useful for later on when one day you change / upgrade to a new meter, or add another one to your kit. Then you can directly compare performance data over time.

See here for tip on how:
http://web.archive.org/web/20070129084754/http://www.midweekclub.ca/powerFAQ.htm#Q23



simplyhankk said:


> and how would you be able to do it with the Garmin?


You can't do it with a Garmin. That was my point.



simplyhankk said:


> I guess this is when people send it their SRMs for calibration?...


Well the exact same issue exists with an SRM - you can validate/check the slope calibration with an SRM powercontrol but not with a Garmin. 

Ironically, the Garmin 500 allows you to change the pre-set slope in an SRM power meter (current wireless models only), but the SRM powercontrol does not (it only keeps the slope in the powercontrol).

The process for checking an SRM is the same as for the Powertap. Static torque check with a known mass hanging from pedal spindle as described in the link above. Do it loaded and unloaded and compare torque values shown to what it should be to make sure the slope is correct.

The difference between SRM and the Powertap (and Quarq) is that only the SRM allows you to change the slope setting if the calibration isn't right. That's a feature that may become available with Quarqs at some stage.


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## simplyhankk (Jan 30, 2008)

Thanks for your info Alex & ukbloke. 

I'm pretty sure THIS is what the Garmin can't do/verify. 

The LYC is just something that can perform this task to ensure the hub's accuracy.


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## kbiker3111 (Nov 7, 2006)

simplyhankk said:


> Well, if you are talking about "value"...then yes.
> 
> PT unit is now overpriced for what it does. Garmin can do a whole lot more with $50ish more and now is more reliable than when it was new


I'm not talking "value", I'm talking straight up price. 

http://www.competitivecyclist.com/


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## Alex_Simmons/RST (Jan 12, 2008)

simplyhankk said:


> Thanks for your info Alex & ukbloke.
> 
> I'm pretty sure THIS is what the Garmin can't do/verify.
> 
> The LYC is just something that can perform this task to ensure the hub's accuracy.


Exactly.

An example of someone with a Powertap torque reading >20% out. Sent it back and got replacement/repair under warranty.

It really is worth checking just so you are sure. It sucks to find out your last X months of data is junk.


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## ukbloke (Sep 1, 2007)

If you are sufficiently computer savvy you use a computer, an ANT+ USB stick and a program called quarqd to monitor the real-time data coming off the PowerTap including instantaneous torque. This is sufficient to check calibration. See here and here for details. The major hassle is that quarqd is not provided as source code and the binaries are for Linux and Mac only.

A simpler option is to find a friend with an ANT+ PowerTap head unit when you want to do a calibration.


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## simplyhankk (Jan 30, 2008)

so i've got the garmin. I'm still trying to get used to it since I was so accustomed to my old computer (Sigma). I am also planning to keep the LYC for the purpose Alex mentioned above...to validate the torque of the hub. 

For the Garmin 500, is it able to

Calculate "Normalized Power"? Or is this something I need to upload the data into a software to be able to find out the normalized power? 

I use "Time" for the time function (used to use "elapsed time" but didn't find it useful) and auto pause/resume. How is the data recorded in that regard... I have a powertap, so would the power data be recorded during those pauses and breaks, or does it automatically ignore those "0" time/power data? 

Thanks for any input.


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## ukbloke (Sep 1, 2007)

I don't think the Edge 500 has Normalized Power, so you will need to use application software for this.

Whether you display time or elapsed time on the Edge makes no difference to the calculations. If you use auto-pause/resume, no data will be recorded for those periods and there will thus be time gaps in the FIT file. It will be up to the application software has to how to interpret this. Some older apps did not like this. If this is considered one ride, then one approach is to include the time but mark it as zero power (which is indeed what happened). The typical recommendation is to include zeroes in your power averaging - this is what WKO+ does, and the Edge 500 can be configured to do that. You shouldn't be able to boost your ride average power by stopping and recuperating!


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## simplyhankk (Jan 30, 2008)

ukbloke said:


> You shouldn't be able to boost your ride average power by stopping and recuperating!


 

Thanks ukbloke

Just wondering what kind of difference it would make. At the end of the day it's accuracy that counts.

Before going to WKO+, which I have read great things about, I'd like to try out golden cheetah.


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## Borti (Aug 1, 2008)

How does one zero the torque on the Garmin?

Thanks.


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## IAmSpecialized (Jul 16, 2008)

Out would be worth noting whether the comparison is being made using the PT joule 1.0 or the new joule 2.0. The 2.0 is actually a bit more expensive than the edge 500 but as far as I can tell is the better unit in practically every way. 

I'm assuming this thread is using the joule 1.0 for comparison?


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## ukbloke (Sep 1, 2007)

IAmSpecialized said:


> The 2.0 is actually a bit more expensive than the edge 500 but as far as I can tell is the better unit in practically every way.


Neither Joule has GPS.


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## IAmSpecialized (Jul 16, 2008)

Indeed, no GPS. I think that is one of the biggest factors for some people.


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## woodys737 (Dec 31, 2005)

Borti said:


> How does one zero the torque on the Garmin?
> 
> Thanks.


Bump...Anyone? A tech at Garmin had no idea a few months ago.


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## chase196126 (Jan 4, 2008)

woodys737 said:


> Bump...Anyone? A tech at Garmin had no idea a few months ago.


Garmin Edge 500
To pair the CinQo:
Menu  Settings  Bike Settings  Bike 1  ANT+Power 
Rescan
“Power Meter Detected” will flash up on your screen when the units are
paired.
To manually zero your CinQo:
Menu Settings  Bike Settings  Bike 1  ANT+Power  Calibrate

That is from the Quarq manual, but it is the exact same for an ANT+ powertap. Just replace CinQo with powetap and follow the menu instructions.


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## woodys737 (Dec 31, 2005)

chase196126 said:


> Garmin Edge 500
> To pair the CinQo:
> Menu  Settings  Bike Settings  Bike 1  ANT+Power 
> Rescan
> ...



Thanks chase! Most guys I know have an older PTs with the yellow CycleOps cpu. They keep telling me I need to be able to verify (zero) torque with my 500/ant+PT. I think this may be the source of a lot of confusion or at least questions on whether the 500/PT combo is giving reliable numbers. Once the 500 is paired and you run through the Garmin calibration process nothing more needs to be verified. The unit is zeroed. 

Now how often a 500/ANT+ PT owner needs to calibrate is the next question as it appears SRM, non ANT+ PT and CinQo need to have torque zeroed regularly. IIRC, there is nothing in the Garmin manual regarding this.


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## Undecided (Apr 2, 2007)

woodys737 said:


> Thanks chase! Most guys I know have an older PTs with the yellow CycleOps cpu. They keep telling me I need to be able to verify (zero) torque with my 500/ant+PT. I think this may be the source of a lot of confusion or at least questions on whether the 500/PT combo is giving reliable numbers. Once the 500 is paired and you run through the Garmin calibration process nothing more needs to be verified. The unit is zeroed.
> 
> Now how often a 500/ANT+ PT owner needs to calibrate is the next question as it appears SRM, non ANT+ PT and CinQo need to have torque zeroed regularly. IIRC, there is nothing in the Garmin manual regarding this.


Verifying and zeroing are two different things. As discussed at length above, you can zero the Edge 500 unit (that is, make it read zero when no torque is being applied to the meter), but it won't display the actual torque that is being applied to the meter and so you cannot use it to verify that the meter is (sufficiently) accurate (e.g., by hanging a known weight).


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## chase196126 (Jan 4, 2008)

woodys737 said:


> Thanks chase! Most guys I know have an older PTs with the yellow CycleOps cpu. They keep telling me I need to be able to verify (zero) torque with my 500/ant+PT. I think this may be the source of a lot of confusion or at least questions on whether the 500/PT combo is giving reliable numbers. Once the 500 is paired and you run through the Garmin calibration process nothing more needs to be verified. The unit is zeroed.
> 
> Now how often a 500/ANT+ PT owner needs to calibrate is the next question as it appears SRM, non ANT+ PT and CinQo need to have torque zeroed regularly. IIRC, there is nothing in the Garmin manual regarding this.


Personally with my powertaps this year (Paired with a Joule) I would zero once per ride after riding for about 15 minutes. The 15 minute window is to allow for the temperature of the hub to stabilize from my Garage to the outside world. 

If I had a particularly important set of intervals, or a field test that I wanted to ensure accurate data for I would zero the unit before beginning that interval. 

As long as your auto zero is working correctly and you zero the torque at the beginning of every ride you should be just fine! 

I hope that answered your question! If you have any others I am happy to help with whatever I can :thumbsup:


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