Speed Sensor Refresh Rate

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tempo36
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Speed Sensor Refresh Rate

Post by tempo36 » Fri Jun 01, 2018 11:07 pm

I am using a Garmin Speed sensor and I've noticed that even when using the "classic" speed data field (not 3s or 5s or 10s) it takes the Karoo ~5-7 seconds to update speed. I've tested this at a stop by just spinning and stopping the wheel (so I know it's not ignoring the speed sensor in favor of GPS data). From the time I stop the wheel until the Karoo realizes it stopped is reliably 5-7+ seconds...with my Garmin Edge 820 it's practically instantaneous.

I think this also explains some of the weird speed numbers I've been getting while doing outdoor TT intervals (The Karoo, for example, thinking that in the middle of a 27 mph sprint my speed drops to 15 mph for a moment and then reaccelerates)

Anyone else having similar issues? Anyone had this issue and found a fix?

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Steve
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Re: Speed Sensor Refresh Rate

Post by Steve » Sat Jun 02, 2018 6:31 am

I have a Garmin hub-based speed sensor and the speed does tend to fluctuate a bit oddly. Your observations are interesting, and I'll try and keep an eye on this on my next rude to see if the oddness that I'm seeing is the same sort of delay thing.

It's been like this for a while now, but I think it used to be better a while back.

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drisotope
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Re: Speed Sensor Refresh Rate

Post by drisotope » Sat Jun 02, 2018 2:13 pm

The latency between the Garmin hub-mounted sensor and the Karoo is so bad I've shelved my Garmin sensor entirely. I'm currently moving a Wahoo Speed around between 3 bikes, because it's shown the best performance. This is 100% a Karoo software issue, as the speed lag and auto-pause delay is present even when not using any wheel speed sensor at all.

Unfortunately as it stands now, your choices are to buy a Wahoo sensor or not use one at all. The Garmin and the Karoo (currently) do not cooperate.

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Steve
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Re: Speed Sensor Refresh Rate

Post by Steve » Mon Jun 11, 2018 7:43 am

Right near the end of my ride yesterday I remembered to have a look at this. Sure enough, my speed readout (using the Garmin hub speed sensor) was delayed several seconds compared to my Garmin. I now wonder if this explains the times I've happened to look in the past and thought that ky speed reading was wrong - perhaps it was delayed. I'll try and remember to have a look earlier in my rides, to see ir it happens all the time or just gradually gets more delayed as the ride goes on.

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drisotope
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Re: Speed Sensor Refresh Rate

Post by drisotope » Wed Jun 27, 2018 11:49 pm

Provided I remember to do so-- tomorrow I will re-activate my Garmin sensor on the Karoo, and pair my Wahoo to my Garmin, and see how the ride times line up. The performance with the Wahoo sensor has been excellent lately, maybe they fixed the Garmin? Anyone else try the Garmin sensor lately?

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Steve
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Re: Speed Sensor Refresh Rate

Post by Steve » Thu Jun 28, 2018 6:58 am

I'm still using my Garmin sensor. I don't look at the speed often on my Karoo since I rely on my Garmin for data. But the few times that I've looked recently, I don't *think* it's had the big delay like before.

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Re: Speed Sensor Refresh Rate

Post by dthempel » Thu Jun 28, 2018 12:00 pm

I'm not convinced my "Connected" sensor is actually even the thing reporting speed on my Karoo. The start/stop lag is horrific as evidenced by the auto-pause, but since both start and stop are affected, it seems to all even out when put up against other rides and other riders doing the same route/pace.

I guess I can "test" the speed sensor since I moved it to my front hub in a recent effort to get it to connect when it was previously misbehaving. I can just pick up the front end and spin the wheel. I have a bunch of little things that I'd like to video-fy, including the SIM when it comes and replacing the bracket foot with the new one.

I'm potentially loaning my Garmin to a friend for her to try out as it seems like her phone has gone completely wacky when recording rides. So I won't have a backup for a while (and haven't ridden with both the Garmin and Karoo in weeks). Might even sell her the Garmin at this point, which either makes me crazy or a reluctant convert?

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drisotope
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Re: Speed Sensor Refresh Rate

Post by drisotope » Thu Jun 28, 2018 1:51 pm

I'm confident enough in the stability of the Karoo to let it fly solo... but until the Karoo has a kJ datafield and Strava Live Segments, the Garmin stays on as wingman. I've only had to use the Garmin for upload once in about 6 weeks, and that wasn't even the Karoo's fault, really (speed sensor battery died.)

Honestly, I've also gotten used to the decadence of two computers-- the Karoo is usually on the map screen, and the Garmin is on the speed/distance/HR/cadence/3S power screen. It's like having an instrument panel and a satnav.

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