Author Topic: Wahoo Elemnt BOLT  (Read 41699 times)

Re: Wahoo Elemnt BOLT
« Reply #100 on: 26 April, 2018, 08:26:40 pm »
I've replied saying that I think the "drift" he's referring to is part of a bigger problem with the Bolt unit itself, and attached another track log which shows the same thing - i.e. the "drift" is the precursor to much bigger GPS discrepancies and eventually a total loss and system lock-up.

Re: Wahoo Elemnt BOLT
« Reply #101 on: 29 April, 2018, 04:40:05 pm »
They suggested a factory reset, which I did.  Went out for a ride today - exactly the same problem.  Around 3-hour mark get the dreaded "drift" with proximity alerts beeping and flashing constantly (VERY irritating).  From then on the tracklog follows a course roughly parallel to my actual route but about 300 metres to one side.  Eventually it locked up completely and so the tracklog is truncated.

I've had enough.  I need to get something that works & can rely on before long summer rides, so it's gone back to Wiggle (just within warranty) for a replacement.

For the first 10 months it was fantastic & I happily recommended it to countless other people.  I really hope they get this sorted.

Re: Wahoo Elemnt BOLT
« Reply #102 on: 03 May, 2018, 01:47:36 pm »
Granted that the longest ride since Oasts and Coasts has been around 100km over 3 hours but since the O&C, I have not experienced any further drop outs of the GPS. Now I wouldn't have a clue if wahoo has updated their software/firmware but I am just putting it down to an anomaly that day.

Re: Wahoo Elemnt BOLT
« Reply #103 on: 08 May, 2018, 04:36:34 pm »
I think it’s the device that does the drifting, not the satellites. My Garmin Edge 520 often does this after a few hours, showing me riding parallel to the road but (for example) 50 metres off to one side. The last time it did this I pulled out my phone that receives information from the same satellites. It showed me on the road.

My understanding is that a GPS device needs to be able to see a certain number of satellites to get an unambiguous absolute position. When the number is below the threshold the device starts to guess based on the satellites it can see, since these can still give it a good idea of *relative* changes in position. If the position was already slightly out then the same error will be repeated as it plots relative position.

I've noticed phones are much less susceptible to this kind of error than pure GPS devices - possibly they have more sophisticated algorithms, possibly they're better at combining other data sources (phone masts, wi-fi, GLONASS etc).

frankly frankie

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Re: Wahoo Elemnt BOLT
« Reply #104 on: 08 May, 2018, 07:35:12 pm »
 ::-)

... happens on completely open ground with no signal-blocking features.  ...
you only live but once, and when you're dead you're done, so let the good times roll

Re: Wahoo Elemnt BOLT
« Reply #105 on: 08 May, 2018, 07:49:26 pm »
STILL waiting for it to get back to Wiggle.  So far it's taken 9 days for the courier service they use (CollectPlus) to get it from the collection point to their warehouse  >:(  (see rant in crap courier thread).

In the meantime Wahoo said I should have sent it directly back to them & they would have issued me a replacement.  Their CS dept have been very helpful and I'm still getting daily enquiries asking what's going on.  They seem as pi$$ed of with Wiggle as I am.

Re: Wahoo Elemnt BOLT
« Reply #106 on: 08 May, 2018, 11:40:28 pm »
::-)

... happens on completely open ground with no signal-blocking features.  ...

On an upright bike at least there’s usually a big lump of meat blocking a significant proportion of the sky. And you can just be unlucky with how many satellites are in view and which directions they’re in.

(Or of course the wahoo software could just not be very good at finding them)

zigzag

  • unfuckwithable
Re: Wahoo Elemnt BOLT
« Reply #107 on: 09 May, 2018, 10:19:41 am »
watching the post ride gps tracks on strava, clubmates who use wahoo gps's have their tracks wandering/drifting much more often than those using garmins. not sure if it's hardware or software related.

Samuel D

Re: Wahoo Elemnt BOLT
« Reply #108 on: 09 May, 2018, 10:52:38 am »
My understanding is that a GPS device needs to be able to see a certain number of satellites to get an unambiguous absolute position. When the number is below the threshold the device starts to guess based on the satellites it can see, since these can still give it a good idea of *relative* changes in position. If the position was already slightly out then the same error will be repeated as it plots relative position.

I think it’s you doing the guessing here, grahamparks! Explain how a precise relative but not absolute position can be calculated without simultaneous signals from four satellites.

GPS works on trilateration (similar to triangulation but with distances rather than angles) with three satellites giving you a location, assuming all clocks involved are accurate and that you’re close to the surface of the earth and/or doing a plausible speed; otherwise you need a minimum of four satellites.

However, since the receiver calculates satellite distances by measuring the travel times of signals at the speed of light, even a tiny error in the clocks causes a large discrepancy of position.

The atomic clocks in the GPS satellites are only accurate to about a millisecond if I recall correctly, but their clock offsets are precisely monitored and new correction data is frequently uploaded to the satellites and thence to your receiver. So the GPS clocks are sufficiently accurate after correction.

The receiver clock offset is another matter. It’s unknown at startup and thereafter subject to the large rate variation of quartz clocks. This is why a fourth satellite is needed: for timing corrections. The mathematics of this correction process is vague to me but involves solving simultaneously four nonlinear equations. This is done in the receiver using Newton–Raphson iteration.

This method cannot be extrapolated to signals from more than four satellites, so all sorts of cleverness is used in those (now typical) cases.

Since we’re guessing, I’d guess the drift described in this thread is a failure of the receiver to keep its clock accurate or to use the latest ephemeris and almanac data from the satellites. Some engineer took the lazy way out, as can trivially be proved by restarting the device and observing that it immediately corrects its fix (but with Garmins, at least, you’ll probably lose your recorded track, cause it to start recording another track, and/or be unable to restart navigation mid-course!).

I've noticed phones are much less susceptible to this kind of error than pure GPS devices - possibly they have more sophisticated algorithms, possibly they're better at combining other data sources (phone masts, wi-fi, GLONASS etc).

Phones are also faster at getting a fix, even when they have cellular data and Wi-Fi switched off so cannot use Assisted GPS to get faster access to the ephemeris and almanac. And my iPhone’s GPS receiver also uses a small fraction of the power of any Garmin I’ve had, although it’s hard to know which subsystem is using the power in a Garmin. Not to mention it locks onto signals in nearly impossible places, like inside a room on the first floor of a five-story building. Garmins don’t do that although my Edge 520 is better than my eTrex 20 with weak signals (on the other hand, it seems to take even longer to get an initial fix, the bigger problem in my use).

I put all of this down to newer, better GPS receivers in most phones and more competent firmware and software.

Re: Wahoo Elemnt BOLT
« Reply #109 on: 09 May, 2018, 11:25:46 am »
Garmins would take forever to get a fix in London however if I use Bluetooth on phone + ELEMNT App connected to BOLT it’ll lock on in a second!

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #110 on: 23 May, 2018, 06:47:57 pm »
Wahoo have a cash back offer at the moment. If you buy an ELMNT you can get £50 cash back.

Re: Wahoo Elemnt BOLT
« Reply #111 on: 23 May, 2018, 07:16:09 pm »
Wahoo have a cash back offer at the moment. If you buy an ELMNT you can get £50 cash back.

And Wiggle have them discounted  to £219   with cash back on top thats  a real bargain

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #112 on: 23 May, 2018, 07:31:58 pm »
Wahoo have a cash back offer at the moment. If you buy an ELMNT you can get £50 cash back.

And Wiggle have them discounted  to £219   with cash back on top thats  a real bargain

It’s showing at £249 for me still at Wiggle. How are you getting the discount?

Re: Wahoo Elemnt BOLT
« Reply #113 on: 23 May, 2018, 07:57:37 pm »
Big Elemnt is £237 for me.
Elemnt Bolt is £189 for me.

Re: Wahoo Elemnt BOLT
« Reply #114 on: 23 May, 2018, 07:58:29 pm »
£219.99 showing for me BUT that's with my Wiggle platinum 12% discount, otherwise it's full whack.

Re: Wahoo Elemnt BOLT
« Reply #115 on: 23 May, 2018, 07:59:19 pm »
I have Gold discount of 5% personally.

Re: Wahoo Elemnt BOLT
« Reply #116 on: 23 May, 2018, 08:02:29 pm »
Wahoo have a cash back offer at the moment. If you buy an ELMNT you can get £50 cash back.

Probably the best deal IF you can wait 60 days for the cash back. I was an early Elemnt adopter and sent it back - subsequently bought a Bolt and have been, by and large, happy with it.

Re: Wahoo Elemnt BOLT
« Reply #117 on: 23 May, 2018, 08:04:44 pm »
Wahoo have a cash back offer at the moment. If you buy an ELMNT you can get £50 cash back.

And Wiggle have them discounted  to £219   with cash back on top thats  a real bargain

It's not clear from the Wahoo offer page if it applies to sales from anywhere or sales just from them (I suspect the latter).

Re: Wahoo Elemnt BOLT
« Reply #118 on: 23 May, 2018, 08:26:08 pm »
Ni its from any retailer other than ebay or amazon  marketplace .  I looked at the T&Cs yesterday  copied below

"All retailers and stockists in the UK are “Participating Retailer(s)” with the exception of purchases from auction websites (e.g. eBay) or marketplace sales through retail websites (e.g. Amazon Marketplace or Play Trade) are specifically excluded from this Promotion. The Qualifying Product must not be sold as part of another Promotion (save for Promotions offered directly by the Participating Retailers). Purchases made through Wahoo Pro Deals are excluded from this Promotion."

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #119 on: 23 May, 2018, 10:26:50 pm »
Thanks, Wiggle discount would explain it. Haven’t spent enough with them recently to qualify it would seem.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #120 on: 25 May, 2018, 09:23:43 am »
Well mine arrived yesterday, set it up but not used it yet. Bit of a niggle is their descision to offset the mount by 90o compared to a Garmin mount.


Anyone know of a cheap source of Wahoo mounts?


PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #122 on: 25 May, 2018, 10:59:00 am »
https://www.sigmasports.com/item/Wahoo/Out-Front-Mount-for-Elemnt-Bike-Computer/EQID

This?

Like that but cheaper :) I can get Garmin ones for less than a fiver! SO was hoping for that price range.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Wahoo Elemnt BOLT
« Reply #123 on: 25 May, 2018, 11:06:54 am »

Re: Wahoo Elemnt BOLT
« Reply #124 on: 31 May, 2018, 12:40:29 pm »
That looks very neat and a lot better than some manufacturers would produce.