Calling all Quarq users - ?'s

Triathlon Forum
1

For all those with Quarq’s - can you please answer/post any/all of the below:

  1. Post type of Quarq and computer.

  2. How much does your offset change and under what conditions? (For example - drops 16 if I go from 40 F to 90 F or estimates of T:).

  3. If you have done the calcs - how much does the above offset change your watts if you do not recalibrate?

  4. Have you ever tested the accuracy of your PM by hanging weights? Results?

Thanks,

David Bassler

2

  1. Cinqo Saturn (x2) Garmin 705

  2. One ranges from -160 to -190s, other is typically -100 to -150 ish

  3. No idea

  4. Yes. The older one just got sent to Quarq for calibration (FREE), as it was reading about 2.5% low. The newer is about 1% high (likely due to changing to a stiffer SRAM Red Sprinter chainring) and that will probably go in for calibration at some point in the offseason too.

3

An offset of 30 for you is about what I see with my SRM which I think equates to about 6-9 watts from 60 cadence to 90 cadence if you don’t recalibrate. I think Quarq uses 1/32 Nm so change of 32 = change in torque of 1 Nm. Multiply that by 2 x pi x cadence/60 = watts.

How do you know your Quarq was reading low/high?

Chainring changes - I read that on the Quarq website. I asked SRM/Colorado tech who said that changing chainrings on the SRM does not change the slope. Aren’t SRM’s and Qaurq’s design essentially the same? Why would it affect 1 yet not the other?

Are both yours SRAM? If you have different ones - which do you like better/why?

Dave

4

For all those with Quarq’s - can you please answer/post any/all of the below:

  1. Post type of Quarq and computer.

  2. How much does your offset change and under what conditions? (For example - drops 16 if I go from 40 F to 90 F or estimates of T:).

  3. If you have done the calcs - how much does the above offset change your watts if you do not recalibrate?

  4. Have you ever tested the accuracy of your PM by hanging weights? Results?

Thanks,

David Bassler

  1. CinQo Saturn Prototype - Garmin 705 (Have used an iAero briefly as well…actually in “tandem” with the 705 for a bit).

  2. Typically no more than 5-10 “units” over any ride and wide temp ranges (i.e. temp swings of up to 30-40F). I always manually zero (through the Garmin) before the ride, and often check it after.

  3. ~1.5 to 3W @ 90 rpm…but since re-zeroing can be done at ANY time by just pedaling backwards at least 4 times, why wouldn’t you rezero if you think conditions have changed?

  4. Yes. The CinQo read ~1% lower than the expected value (an average across chainrings and cogs). By comparison, my PT wheel read ~0.3% higher than expected.

Are you looking at buying a new PM?

5

So if 10 units: 10/32 Nm x 2 x pi x 90/60 = 2.95 watts? Thats how I’m doing my calcs…so I think I’m doing it right.

My SRM swings more like 1 Nm I think - I’m still playing with it.

I would rezero by pedaling backwards if I had a Quarq/CinQo but I have an SRM.

I may get a Quarq for my road bike for the fun of it :). I like the SRM except:

  1. Its a pain to recalibrate while riding with the 705.
  2. With the 705, the max offset is 1000 and my baseline is 630. My slope is 25.1 so my max torque I can check with weights is < 15 Nm which is less than 150 watts at 90c. I can’t check the slope up to 300 watts equivalent. I e-mailed Garmin to fix this.

When you measure with weights - do you use a series of weights like 5/15/25/35 pounds? Do you check the R and L crank and average them? How close should the L and R measurements be?

Do the measurements change much from ring to ring and cog to cog?

I assume as it gets hotter with Quarq and other SRM’s - that the offset should always drop lower?

How do you do the weight thing with a PT? Is it exactly the same? Do you need to correct for drive chain losses or not as nothing moves?

Last one: SRM said that I can change chainrings and it won’t affect the slope. Think thats true or false?

Thanks - good to hear from an expert.

Dave

6

For all those with Quarq’s - can you please answer/post any/all of the below:

  1. Post type of Quarq and computer.

  2. How much does your offset change and under what conditions? (For example - drops 16 if I go from 40 F to 90 F or estimates of T:).

  3. If you have done the calcs - how much does the above offset change your watts if you do not recalibrate?

  4. Have you ever tested the accuracy of your PM by hanging weights? Results?

Thanks,

David Bassler

  1. Quarq Cinqo Saturn (FSA) with Edge 705

  2. I’m normally from 183 to 187.

  3. ?

  4. No, just against my CT and they’re virtually identical.

Ken

7

So you went with the quarq! :slight_smile:

8

When you measure with weights - do you use a series of weights like 5/15/25/35 pounds? Do you check the R and L crank and average them? How close should the L and R measurements be?

I’ve used 25# and 50# and I typically just check the R crank. I didn’t see any meaningful difference between the R and L.

Do the measurements change much from ring to ring and cog to cog?

Ring to ring? Yes (but only by <1% or so). Cog to cog? Not that I’ve seen. I have done “sweeps” across the cogs in the past just to see if it affected the PT wheel at all.

I assume as it gets hotter with Quarq and other SRM’s - that the offset should always drop lower?

Dunno…I don’t really pay attention to which way the offset goes since it basically just “bounces around” within a 5-10 “unit” window. And, like I said earlier, it’s not that much of a concern since I can just backpedal and zero it whenever I feel like it :slight_smile:

How do you do the weight thing with a PT? Is it exactly the same? Do you need to correct for drive chain losses or not as nothing moves?

The same…and actually, I use the PT wheel as the “guide” to tell me when I have the weight is at “max torque”. With the PT in “torque mode”, you see a live readout of the torque. I can slowly lift the weights up from the floor by rotating the wheel backwards (bike is in a trainer) and then I SLOWLY rotate and hold until I find the max torque reading. At that point, I clamp on the rear brake to hold it in place and then take an offset reading of the CinQo.

Since the drivetrain isn’t moving, there are no frictional losses. The torque is the torque. You do have to “correct” for the gear ratio to get the expected torque at the rear hub though.

Last one: SRM said that I can change chainrings and it won’t affect the slope. Think thats true or false?

They might say that…but I think I’d still check it…especially since you can change it if it’s off with the SRM, right? I think this would depend on what chainrings you’re talking about. For example, going from a “spidery” road chainring to a solid, machined, TT chainring I think I would expect to see some differences.

I guess I’d go back to the old engineering adage “When you change something, something typically changes” as a guide in that case :wink:

Dave

9

For all those with Quarq’s - can you please answer/post any/all of the below:

  1. Post type of Quarq and computer.

  2. How much does your offset change and under what conditions? (For example - drops 16 if I go from 40 F to 90 F or estimates of T:).

  3. If you have done the calcs - how much does the above offset change your watts if you do not recalibrate?

  4. Have you ever tested the accuracy of your PM by hanging weights? Results?

Thanks,

David Bassler

  1. Cinquo FSA Team Issue + Garmin 705 (software 2.6)
  2. always around -400
  3. 7% at maximum
  4. not by hanging weight but on hard climbs mounted seated against mathematical calculator and it was pretty accurate.

Otherwise, I now have an issue with my 705. As I’m stopping pedaling, after 3-4 seconds where it logically appears 0 rpm and 0 watts on the Garmin, it start to “give” me “4651rpm and 159watts” until I start pedalling again.
Does anyone had the same experience ? Any advices ?

Thanks in advance !