| Forums » Quarq Discussion » Zero Offset calibration (12 posts) |
| Zero Offset calibration | |
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DavidH1 year, 8 months ago |
Hi, Has anyone had zero offset numbers outside of the -500 to +500 range and managed to get if solved without sending it back. I'm based in the UK and just recieved my Cinco last week. It installed fine and paired up with my Gramin 705 (latest firmware) without issue, however, when I run the zero offset calibraion I have generally got a number back in the high -600s, with a couple over -900.. I did mail support on tuesday evening and got a suggestion to loosen and re torque the chainring bolts to 10Nm. I did this but am still getting numbers back in the -550 to -650 range. I mailed support again yesterday, but haven't had a reply yet. because of the time difference, I can't call until later this evening. Anyone have any ideas, I really could do without losing this as I have a couple of imprtant races over the next 2 weeks. Cheers David. |
jgkehoe1 year, 8 months ago |
Hi Dacvid, I have had a similar experience. Brand new Cinco, installed last Friday. First ride on Saturday was -91, Garmin 705 crashed so only part of the data, but which looked suspiciously high. Did a 10 mile training TT yesterday that gave crazy power numbers. Basically had to ditch the data ... zero was -104 before, and I unfortunately did not check it afterwards ... Zeroed manually today and zero value has jumped to -636/-638. Did another zero after the ride (4-5 C warmer and +70 m) and it has gone to -663. With my SRM, the zero value (yes, different units) only varies from 750 to 770 for wide range of temperature (-5 C to + 25 C) + altitude Question to Quarq: If the zero value is outside -500 to +500, does this indicate a problem with the unit? Maybe someone in Quarq can post an explanation here as seems to be a general concern? |
DavidH1 year, 8 months ago |
Hi J. Sounds very similar. Just gotback from a 50k ride, zeroed before I started and got a -642, ran it again after the ride and got something in the high -700s. Temperature wouldn't have really varied over the duration of the ride. it was a rolling route but no major elevation changes either. Seems to be all over the place. Which software version are you using with the 705? |
jgkehoe1 year, 8 months ago |
Hi David, I don't think the Garmin has much to do with it as the zero and slope are held in the CinQo. My 705 has software ver 3.10. I also looked on the Wattage blog - see link http://groups.google.com/group/wattage/browse_thread/thread/c407431f429e15bf/847ac8d7c7b06456 On the blog, they say a difference of 3 on the zero for the Quarq is typically around 1 W. So on this basis, if the zero varies by 100, your power could be out by 30+W. They also mentioned advice from Quarq on loosening + re-tightening certain bolts to fixed torque, and people had same issue of zero drifting back again. My Quarq is also brand new (110) unit, so bit surprising if bolts or something are a problem. Will be interesting to see what Quarq advise. The objective is to make sure we get the +/- 2% accuracy they advertise, otherwise the whole point of power based training will be lost. as you can be training in the wrong zone. |
DavidH1 year, 8 months ago |
Hi J. I had read that there were some anomolies with the zero offset in one of the older release of the 705 software. but that added something like 65000 to the figure. Anyway, I spoke to Shayna at Quarq this afternoon, who was very helpful, but the upshot is that it needs to go back to them. I'm going to have to send it back via the distributor here in the Uk otherwise it's going to cost me a small fortune to fedex it myself (not really on for something brand new and pretty expensive) Unfortunatley this means i'll probably be without it for the next couple of weeks, which screws my "A" race for the year as I sold my PT to finance this. Pretty dissapointed :-( |
jgkehoe1 year, 7 months ago |
Mine is now having to go back too. Went through same steps of re-torquing the chain ring bolts which put zero back to acceptable range - unfortunately zero went progressively downward on first ride today after re-torquing bolts (progressively from -66 to -626 during 2 hour ride). Shayna promises that Quarq do a very quick turn around for repairs, so fingers crossed that I can get mine back quickly. |
ttbikefit1 year, 7 months ago |
This seems to be an epidemic. I have two clients with brand new units (SRAM via QBP) and one uses an Edge 500 and the other a 310xt. Both have started reading bogus values or not at all, one calibrates to -900 and the other to -700. I have two others sold to clients that have shown evidence of changing offsets during a ride.So now I apparently have to remove at least 2 units and send them back?? What's up with that Quarq? |
gv1 year, 7 months ago |
Same problem here, with a two week old SRAM in the UK. Calibrated at -177 just before doing a 25 mile TT last night, then did another calibration at the end and got -37. That means the error at the end, at a cadence of 100, was 140/32 * 100/60 * 2pi = a whopping 46 watts. I saw a corresponding difference of 33 watts between the average power for the 2 laps - although the average speed was the same. There was a 3.5 deg C temperature drop over the hour. Useless. |
Jim@Quarq1 year, 7 months ago |
Hi All, There is a problem here. The calibration variations you are describing is not normal and we will make sure that all these issues are corrected. Please email us directly at thinkfast@quarq.us and we will arrange the best way to handle things. If you are in the UK, please note the shop (and distributor if possible) from which you purchased the unit. We have previously seen this behavior come from a mechanical issue at the chainring bolts or at the spider to crankarm interface. Things to try / inspect: Chainring bolts: Remove all the chainring bolts, and inspect the nut side for 'mushrooming'. If the nut side has mushroomed, then it may be sticky or difficult to remove from the spider. Replace any damaged or mushroomed nuts with another steel chainring bolt set. Retorque the bolts to 10 Nm. Spider Fit: The spider must fit on the crankarm without any slop or wiggle, but it is not a press fit. We use Loctitie 638 retaining compound (green) on the interface from the spider to the crankarm and Loctitie 243 Medium threadlocker (blue) on the bolts. It is possible that we have a tolerance issue creating a loose fit between the crankarm and the spider. This can be corrected with retaining compound that is capable of filling larger gaps. If you feel inclined, you can remove the spider from the crankarm using the three T25 torx bolts on the back. Then scrape off the green Loctite from the spider and the crankarm. Then apply a high strength epoxy such as JB Weld or similar on all the interface spline between the crankarm and spider, being careful to not allow any epoxy to get on the any threads for the torx bolts. Then put Loctite 243 on the three bolts and reinstall to 10 Nm. Allow the epoxy to set. If everything is corrected, the calibration value should stabilize. Note the absolute value is not important, so if it settles in at -640 to -670 that will be fine. Mainly we need the calibration to be stable. You are welcome to attempt these fixes or not, in any case please keep in touch with us. We will make sure everyone's issues get addressed. I apologize that you are experiencing these issues. Jim PS - Internally, we prioritize email over the forum posts, so be sure to email or call when you need help. |
gv1 year, 7 months ago |
Jim, Thanks for the prompt reply. Looking at the data it does appear that there's a step change in power from one point onwards rather than a steady drift - consistent with something slipping. This is very clear looking at 5min averages. Anyway, I'll follow up by email. ps sorry about the "useless" comment. That was just frustration, as I was hoping to get a FTP estimate out of the ride - which I now realise I can still get by adding on that torque offset x cadence (rad/s) from that point onwards. |
DavidH1 year, 7 months ago |
Hi Jim, I returned my PM, last week, to SRAM in the Uk via the shop it was purchased from. Apparently it will be back to me next week, but I'll mail these details in, just so you have a record of it. |
DavidH1 year, 7 months ago |
As an update, the retailer has given me a new set of cranks as the UK distributor was estimating another 2 weeks before they could get them back to me. Latest set seems to be pretty solid. Have been playing around with it over the last couple of days and the offset is consistently coming back in th -250 range. |
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