Power meter weight penalties
Moderator: robbosmans
I rode a quick test ride with my new Stages PM and it works... That's all I can say for now about the functionality before I start learning how to use it and analyze the data better. The biggest drawback from a ww perspective is that the SRAM Rival crank arm is a beast at 210g + 20g for the Stages PM ( = 230g total). The SRAM Red arm that it had to replace is 135g. So for SRAM Red owners, the Stages weight penalty is 95g and not 20g.
(2012/2014) Scott Addict R1, SRAM Red 6.6kg | 2012 Scott Scale Pro, SRAM X0, 9.4kg
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My quarq has crapped out twice in 8 months....both times on wet rides (though the local distributor said it wasn't water ingress).
Good things:
-it's easy to replace a battery.
-Pretty light.
-Looks good (my opinion)
-good replacement (second time was over the weekend)
-data is consistent and decent once you use a qualvin app and a known mass.
Bad things:
-2 breakdowns.
-each time it's been sent back, it's been miles out from accurate and needed re-calibrating using Qualvin to get it sorted (which would be a pain if my coach didn't have that stuff and an obsessive hatred of inaccurate data, so I CAN get it fixed promptly).
I may just be the least lucky person in NZ with Quarqs but it has severely tried my patience as each breakdown has coincided with a holiday period starting (i.e. when I'm likely to do some serious K's!!)....second one was recent and really caused a temper tantrum.
Good things:
-it's easy to replace a battery.
-Pretty light.
-Looks good (my opinion)
-good replacement (second time was over the weekend)
-data is consistent and decent once you use a qualvin app and a known mass.
Bad things:
-2 breakdowns.
-each time it's been sent back, it's been miles out from accurate and needed re-calibrating using Qualvin to get it sorted (which would be a pain if my coach didn't have that stuff and an obsessive hatred of inaccurate data, so I CAN get it fixed promptly).
I may just be the least lucky person in NZ with Quarqs but it has severely tried my patience as each breakdown has coincided with a holiday period starting (i.e. when I'm likely to do some serious K's!!)....second one was recent and really caused a temper tantrum.
Updated: Racing again! Thought this was unlikely! Eventually, I may even have a decent race!
Edit: 2015: darn near won the best South Island series (got second in age
-group)..woo hoo Racy Theremery is back!!
Edit: 2015: darn near won the best South Island series (got second in age
-group)..woo hoo Racy Theremery is back!!
I think the Quarq numbers are questionable at best. They're no longer available on FSA cranks, so I suspect that weight was the previous generation unit.
The standard Quarq Riken these days is Sram crank based and weighs 739 for GXP and 733 for BB30g. The comparable Sram Red crank is 609 in GXP and 557 in BB30.
The difference is 130g GXP, 176g for BB30.
Neither of my Quarks have broken or lost accuracy yet. But it's only been four years for the older one.
The standard Quarq Riken these days is Sram crank based and weighs 739 for GXP and 733 for BB30g. The comparable Sram Red crank is 609 in GXP and 557 in BB30.
The difference is 130g GXP, 176g for BB30.
Neither of my Quarks have broken or lost accuracy yet. But it's only been four years for the older one.
On the subject of Stages, or the new left-only Rotor... I get L-R balances like the following very reliably with Vector:
Measuring just the left side would thus result in a significant power error in the low-power range.
Measuring just the left side would thus result in a significant power error in the low-power range.
- HammerTime2
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Then go with Stages or the left-only Rotor. Your all-important high-end power* will increase.
* as indicated by the multiply left-side power by 2 algorithm, ha ha
Edit: For NiFTY's benefit, at the very highest power shown on the graph, djconnel's right leg percentage tends to be below 50, therefore, his left leg percentage tends to be above 50, so doubling left leg percentage will overstate power, hence his <indicated> power will increase by use of a left-leg only power meter. QED.
* as indicated by the multiply left-side power by 2 algorithm, ha ha
Edit: For NiFTY's benefit, at the very highest power shown on the graph, djconnel's right leg percentage tends to be below 50, therefore, his left leg percentage tends to be above 50, so doubling left leg percentage will overstate power, hence his <indicated> power will increase by use of a left-leg only power meter. QED.
Last edited by HammerTime2 on Fri Jul 18, 2014 7:20 pm, edited 1 time in total.
Actually Hammertime calculated power will decrease for djconnel. I have a Quarq which estimates balance and mine is normally 48-49% L and 51-52% R. I know that my FTP set on my quarq is going to be slightly higher than that on my stages. Does 1-2% really matter, not really. Power fluctuates a fair bit on any real road surface so trying to hold a wattage to a single watt is almost impossible. I also don't stare at my stem with the intensity of Froome so a general band of band of watts +/- 10/15 of target is my goal. Now I am waiting so someone to say that on their SRM they sit on exactly their target wattage within 0.5W and notice no fluctuations over a regular road as they have their legs so well tuned to road irregularities. Activate powermeter trolls now.
Evo 4.9kg SL3 6.64kg Slice RS 8.89kg viewtopic.php?f=10&t=110579" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
Here's another way to look at it: as a complete drivetrain:
SRAM Red 2013 Quarq - 793g
HSC BB w/o Sleeve - 81g
Speedplay Ti Zeros - 164g
Total = 1,038g
Price = $2,000 + $110 + $335 = $2,445
THM M3 SRM w/ FSA Compact Rings - 698g (cyclingtechblog)
THM English BB - 72g (according to Fairwheel)
Speedplay Ti Zeros - 164g
Total = 934g
Total Cost = 2,745 (from SRM) + $160 (Praxis) + $335 = $3,240
THM M3 w/ Spider - 384g
Praxis Rings plus bolts - 130g
THM M3 English BB - 72g
Garmin Vectors - 350g
Total Weight = 936g
Total Cost = $996 + $160 + $1700 = $2,856 (THM from R2-Bike)
Rotor PowerMeter Compact w/ Praxis Rings - 761g
Rotor BSA 30 BB - 96g
Speedplay Ti Zeros - 164g
Total = 1,021g
Price = $90 + $2,400 + $160 + $335 = $2,985
No Powermeter
THM M3 w/ Spider - 384g
Praxis Rings plus bolts - 130g
THM M3 English BB - 72g
Speedplay Ti Zeros - 164g
Total Weight = 750g
Total = $996 + $160 + $335 = $1,491
SRAM Red 2013 Quarq - 793g
HSC BB w/o Sleeve - 81g
Speedplay Ti Zeros - 164g
Total = 1,038g
Price = $2,000 + $110 + $335 = $2,445
THM M3 SRM w/ FSA Compact Rings - 698g (cyclingtechblog)
THM English BB - 72g (according to Fairwheel)
Speedplay Ti Zeros - 164g
Total = 934g
Total Cost = 2,745 (from SRM) + $160 (Praxis) + $335 = $3,240
THM M3 w/ Spider - 384g
Praxis Rings plus bolts - 130g
THM M3 English BB - 72g
Garmin Vectors - 350g
Total Weight = 936g
Total Cost = $996 + $160 + $1700 = $2,856 (THM from R2-Bike)
Rotor PowerMeter Compact w/ Praxis Rings - 761g
Rotor BSA 30 BB - 96g
Speedplay Ti Zeros - 164g
Total = 1,021g
Price = $90 + $2,400 + $160 + $335 = $2,985
No Powermeter
THM M3 w/ Spider - 384g
Praxis Rings plus bolts - 130g
THM M3 English BB - 72g
Speedplay Ti Zeros - 164g
Total Weight = 750g
Total = $996 + $160 + $335 = $1,491
Hollowgram stages
SISL2 compact 484g
+ stages arm (170 SI arm as SISL2 unavailable currently - 124g SISL2 arm weight) = +46g
+HSC BB w/o Sleeve - 81g
+Speedplay Ti Zeros - 164g
= 775g
$975 + $800 stages + $110 + $335 = 2220.
SISL2 compact 484g
+ stages arm (170 SI arm as SISL2 unavailable currently - 124g SISL2 arm weight) = +46g
+HSC BB w/o Sleeve - 81g
+Speedplay Ti Zeros - 164g
= 775g
$975 + $800 stages + $110 + $335 = 2220.
Evo 4.9kg SL3 6.64kg Slice RS 8.89kg viewtopic.php?f=10&t=110579" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;
SRAM Red drive side + Rival w Stages left side (w eBay purchases)..
SRAM Red 53/39 GXP exogram rings drive side only: 474g
SRAM Rival left arm w Stages: 230g ( )
VCRC ceramic GXP BB: 93g
Speedplay CrMo w aftermarket Ti spindles: 160g
= 957g (182g heavier than Hollowgram combination posted above)
SRAM Red GXP $230 (new eBay) + Rival w Stages $500 (almost new eBay) + $89 VCRC (new eBay) + pedals $129 + $75: $1023
Note SRAM Red cranksets are around $290 now. And Rival arms are closer to retail $700. I was lucky.
SRAM Red 53/39 GXP exogram rings drive side only: 474g
SRAM Rival left arm w Stages: 230g ( )
VCRC ceramic GXP BB: 93g
Speedplay CrMo w aftermarket Ti spindles: 160g
= 957g (182g heavier than Hollowgram combination posted above)
SRAM Red GXP $230 (new eBay) + Rival w Stages $500 (almost new eBay) + $89 VCRC (new eBay) + pedals $129 + $75: $1023
Note SRAM Red cranksets are around $290 now. And Rival arms are closer to retail $700. I was lucky.
(2012/2014) Scott Addict R1, SRAM Red 6.6kg | 2012 Scott Scale Pro, SRAM X0, 9.4kg
I would echo what Showdown said. Started with a PT and it was a good introduction but limiting. Then went to wired SRMs. These were bulletproof, reliable, and consistent but eventually wanted to get away from wires. Had 3 Quarqs after that. Absolutely agree that they are very good products with exceptional customer service. I never had an issue with any of mine. Just recently moved to Stages as I like the flexibility of the new 9000 cranks and I like how inconspicuous it is. Also doesn't hurt that it's lighter.... I don't have a lot of experience on it yet but so far its been really good and the numbers aren't out of line with what I would expect.
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Firefly Ti Gravel Disc
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Santa Cruz Blur 2019
Gaulzetti Cabron Disc (Retired to the Kickr after an accident)
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As the author of the original content on CPL I wanted to chip in and say that, while it's one of a range of data people find interesting, I don't think weight should feature very highly on the list of priorities when choosing a power meter. It's a tool to help do the job of improving your watts/kilo way beyond any small weight penalty so the considerations should be more in terms of accuracy, reliability, usability, maintainability. I encourage people to think about total cost of ownership. At one end of the spectrum SRM's are for life, fault-free-availability will be close to 100% of days and resale values are good. At the other end some units have low upfront cost but are questionable on other criteria.
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