Garmin CSC10 speed issues

belpersnapper

Hi folks. I have searched for an answer on the forum but no luck so here goes

I'm using a Garmin 305 and CSC10 sensor on my turbo set up.

Everything works fine except the speed is erratic to say the least. Cadence is fine but the speed jumps from 15 to 32 to 48 mph while steady pedalling. Also on uploading data I'm clocking 78+ mph !!! (Should I think of turning pro???)

I've tried the re-matching, tried GPS off, tried magnet moving, tried custom wheel size, tried using the actual 700x23 setting. Nothing cures the problem - is there anything I'm missing ?.?

Thanks in advance

Mikey23

Has it ever worked right? Pretty straightforward system really... All that happens is that magnet goes past a sensor and triggers a calculation. Are 15 32 48 actual figures? My 500 gives me a high and low figure when I first start but quickly locks on to an average. The speed sensor overrides gps speed in any case but I need to turn gps off manually when on the turbo. What happens when you take the magnet off and it has to use the 305 gps?

belpersnapper

Hi Mikey
The figures were examples of how the speed changes within seconds as I'm pedalling, it's a sort of 15 then 24 then 32 then it's 15 again then 26 and keeps going like that - never stays at a steady speed.
305 works fine outdoors on GPS
I think it worked fine back in January on the turbo but I've got 3 of these on different bikes so may be that was a different one (sorry can't remember)

dw300

Im not being funny, but is that different from a GSC10? I have one of those that exhibits the same problem.

Mikey23

How long have you had it? Still under warranty? Battery need changing? If the magnet is next to the unit in storage it will still be working and battery will drain quickly. Mine works perfectly ATM but only had it a few weeks

belpersnapper

Sorry yes it's a GSC 10 - I assume you haven't sussed it out dw300 ?
Not had this one very long a few months at most.
Tried another reset and magnet move this morning - same problem.
Interestingly if I spin the wheel quickly and leave it running the speed stays constant and slowly decreases as the wheel slows down - not erratic readings. When I start pedalling again the speed starts the erratic jumping again.

pcb24

Distance the magnet from the unit ( 5mm gap). I have the same issue but have been told to try this

FatTed

I guess the magnet on your crank is somehow interfering with your speed sensor?
have you turned off your GPS on your Garmin and also auto pause? (whilst on the turbo)

dw300

belpersnapper wrote:

Sorry yes it's a GSC 10 - I assume you haven't sussed it out dw300 ?
Not had this one very long a few months at most.
Tried another reset and magnet move this morning - same problem.
Interestingly if I spin the wheel quickly and leave it running the speed stays constant and slowly decreases as the wheel slows down - not erratic readings. When I start pedalling again the speed starts the erratic jumping again.

All I know is ..

Its not the crank magnet as I've tried it without one, and have tried my other GSC10 with the crank magnet and it works fine.

I've changed batteries.

I've done the reverse battery reset.

I've tried different magnet distances and difference speed magnets (my speed was erratic).

Just contact Garmin. They'll email you and come get it and fix it as long as you have a receipt. You dont have to have registered accessories, but if it came with a head unit you'll need to have registered that. In the end i couldnt get a copy of the receipt from the shop, so they too it on the chin and ordered another. Although they said they'd probably get a freebie from the Garmin rep in exchange for the faulty one. They're probably worth no more than £20 to Garmin.

belpersnapper

Thanks folks - looks like a return to Amazon for this one then