Lightest ANT+ compatible head unit for a power meter?

Discuss light weight issues concerning road bikes & parts.
claus
Posts: 256
Joined: Fri Oct 31, 2008 10:04 pm

by claus

I'm looking for a light ANT+ compatible head unit that can record power data (besides speed/cadence/HR) such that it can be downloaded to a computer later on. Preferably it should also be able to not just display the current power, but also some average (e.g., 3s) to deal with something like PowerCal.

Some head units that I checked/have:
- CycleOps Joule 1.0: 43.5g
- Garmin Edge 500: 57.6g
- SRM PC 7: 69g

Unfortunately I'm having a lot of problems with the Joule: the battery lasts less than 15 hours of riding (a new firmware supposedly fixes that), it shows lots of bogus rides (e.g., from 2037 with -5371km, or 1 minute ride time but 300km; and it seems impossible to get rid of them) and right now it is completely "dead": no display activity at all - even with a new battery, so I'm looking for an alternative that is lighter than the Edge 500 (and reliable!). Any suggestions?

User avatar
btompkins0112
Posts: 2693
Joined: Fri Feb 11, 2011 3:04 am
Location: Mississippi

by btompkins0112

The Garmin is the industry standard.....save weight elsewhere.

by Weenie


Tillquist
Posts: 1593
Joined: Fri Dec 30, 2005 3:33 pm
Contact:

by Tillquist

btompkins0112 wrote:The Garmin is the industry standard.....save weight elsewhere.


+ 1
See all my bike h e r e

sungod
Posts: 1561
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

if you want long battery life, the srm is the one, bulletproof but pricey

for light weight there's the motoactv at 35g, not sure how good the display is for cycling, and as it has gps, the battery life is probably not great

5 8 5
Posts: 1353
Joined: Sat Jul 29, 2006 2:36 am
Location: UK

by 5 8 5

The soon to be released Cateye Stealth 50 has a small form factor. Can't find any exact weight specs for it though.

User avatar
djconnel
Posts: 7926
Joined: Wed Sep 26, 2007 1:57 pm
Location: San Francisco, CA
Contact:

by djconnel

For GPS-enabled The Leikr looks to be the upcoming lightest, but (1) it's still Kickstater, which has an exceptionally high vapor rate, (2) no handlebar mount yet, just wrist, (3) sampling rate is an open question, as it's now running focused, but that's just a software matter and the software may not be fully written.

Note the 55 gram weight includes a wrist strap. 55 is basically a tie with the Edge 500 (57 g) without its mount. So w/o its strap it's probably down int he 35-40 gram range. The Edge 510 is considerably heavier (75 g, more or less).

Image

No GPS and Specialized Speedzone Expert is ANT+ enabled. I saw one on Ned Overend's bike @ the Diablo Hillclimb in 2011 after it was showed @ Interbike 2010, and it seems it's finally being publicly released. But a bike computer in that price range needs GPS these days because of Strava and its social media and competition aspects. People think phones will take over this role but I just don't see it: the phone will go into the bike computer rather than vice-versa. Phones just aren't well suited as cycling head units.

An example for why GPS is going to be needed is week 4 of my hillclimb series this year Sure, this isn't a race, but rather a fun competitive ride, but on this particular week I'm scoring people based on how they ride 6 climbs as I derive from their GPS data. There's errors in timing which result but I can do better than Strava with my own custom timing code since I use a different algorithm (interpolated line crossings versus uninterpolated point approaches). It's finally to the point where everyone either owns or can borrow GPS, either phone or otherwise, in this region. In any case, there's clearly going to be more of this sort of thing in the future.

On the Garmin/non-Garmin issue Garmin is first to the table with new ANT+ features, since they own Dynastream, which controls the ANT+ standard. So things like L-R power balance hit the Garmin units first. Next thing is probably some sort of "pedal stroke quality" index. They're also good about providing different types of power (instant, 3-second, interval avg, ride-avg). But if all you wants is watts, this may not be important to you.
Last edited by djconnel on Sun Jan 20, 2013 7:31 pm, edited 1 time in total.

User avatar
ferrarista
Posts: 1671
Joined: Tue Sep 28, 2004 7:39 am
Location: Canada

by ferrarista

The Joule 2.0 is pretty good too. 20 hours of riding , nice big readable screen, waterproof, and pretty compact.

I just weighed one and its 76gr. I would not worry about a couple grams. You can save weight on other things.
██

Geoff
Posts: 5136
Joined: Sat Dec 13, 2003 2:25 am
Location: Canada

by Geoff

If you aren't running an SRM PowerMeter, you may have issues with the PC7. If you are running SRM, the PC7 is pretty hard to beat from the perspective of reliability, data storage and transmission and battery life.

User avatar
Tapeworm
Posts: 2585
Joined: Thu May 03, 2007 10:39 am

by Tapeworm

^ +1 on that. I like my PC6 very much indeed, but as mentioned doesn't like to play with others.
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
"I'm not a real doctor; But I am a real worm; I am an actual worm." - TMBG

claus
Posts: 256
Joined: Fri Oct 31, 2008 10:04 pm

by claus

Thanks for the suggestions about light alternatives, I will look forward to seeing the CatEye, Specialized, etc to be released.

The main purpose of the head unit will be to record the "power" data from the PowerCal, which I intend to use in conjunction with my "light" bike; hence "saving weight elsewhere" doesn't make much sense for this. Currently only my training bike has a power meter and since I'm trying to be a bit more serious about "training with power" I also want at least some estimation of it when I ride a different bike.

I have no intention to use those "social" sites, so I don't really need GPS (however, it allows to not having a speed sensor, so there might be some overall weight saving).

User avatar
djconnel
Posts: 7926
Joined: Wed Sep 26, 2007 1:57 pm
Location: San Francisco, CA
Contact:

by djconnel

My power meter itself (PowerTap) is exceptionally heavy, so when I do hillclimbs I use data from my Edge 500 in conjunction with a power-speed model I calibrate against other riders who did the same climb in the same conditions with power meters. It's quite a hassle, but even a few seconds in a climb can make a difference. But in doing this I lose pacing data: I still have the Garmin VAM number, but that's imprecise over small times. And I completely agree with you that it's important to save weight where you can. It's not a zero-sum question.

I'm disappointed no ANT+ Sport lightweight no-display recording devices have been released. Some friends of mine have built these from hobby kits with chips like this: http://www.ti.com/ww/en/mcu/ant/index.shtml . But it's not a practical solution for most people.

LionelB
Posts: 1471
Joined: Sun Oct 05, 2008 8:09 pm
Location: Aix en Provence

by LionelB

Is there a PC7 with GPS planned ?

JN2Wheels
Posts: 219
Joined: Sat May 09, 2009 3:03 am
Location: Maryland

by JN2Wheels

djconnel wrote:I'm disappointed no ANT+ Sport lightweight no-display recording devices have been released.


DJ, I've been following dcrainmaker's coverage of the 4iiii Viiiiva Heart Rate Monitor. It is a heart rate monitor that consolidates all Ant+ and Bluetooth 4.0 signals into one output. There is also an accelerometer and some storage. Further development may include the ability to record all the inputs in the HR strap itself. Not quite out yet, but check out the latest updpate from CES, if you're interested.

http://www.dcrainmaker.com/2013/01/ces- ... -week.html

Will solve some problems as devices transition away from Garmin's standard over to the open Bluetooth Smart stuff.

User avatar
djconnel
Posts: 7926
Joined: Wed Sep 26, 2007 1:57 pm
Location: San Francisco, CA
Contact:

by djconnel

Thanks. But that's still going to be heavy. For racing, you're not going to be carrying your phone.

by Weenie


JN2Wheels
Posts: 219
Joined: Sat May 09, 2009 3:03 am
Location: Maryland

by JN2Wheels

No. That's my point. The device has the capability to record .fit files. Then wirelessly transfer after the event. No computer/phone/display needed. All you carry is the heart rate strap. And power meter, if desired.

Post Reply
  • Similar Topics
    Replies
    Views
    Last post