Simple none GPS computer with odometer which also has gradient readings?

[Alex321]

Thought that both distance traveled and gradients would be useful information to know. Gradient doesn't have to be instant, just what has been done on the trip which can be relayed anytime. I read that the more accurate ones would have a delay so this not a problem.

I fear that a computer with gradient must by necessity also have a bunch of bells and whistles I wouldn't want and thus a hefty price tag.

I also stipulate I don't want GPS as I like to be disconnected from the grid when riding. Same reason I choose to use paper maps rather than new fangled computers. These two things above though would be useful to me on a computer but nothing else.

GPS is not connected to the grid. It just senses the satellite signals and positions and calculates position based on a triangulation of those.

And you aren't going to find a modern one which works and doesn't have GPS. In order to know gradient, they HAVE to have both the distance you have travelled and the change in elevation. Nobody in going to put good enough barometric sensors into a non-GPS (and therefore cheap, since almost anybody with an interest such stats nowadays wants GPS).

 

[bighipspeddler]

It doesn't matter too much for gradients as the time period is too short for air pressure changes to have any effect

I was thinking too that for gradient it doesn't matter at all does it that the altimeter is inaccurate so long as it measures changes from x to y for the gradient, right? so it just has to be accurate to itself?

you aren't going to find a modern one which works and doesn't have GPS.

The sigma looks absolutely fine to me and reviews say so too generally. Also @andrew_s said theirs was 'very good':

I used to have a Ciclosport CM414 cycle computer/altimeter which I found very good, given fair weather.

What @si_c says seems to be the opposite of your claim:

Accuracy of GPS for elevation - and thus calculating a gradient from it - is very poor, satellites look down not from the side so the resolution of vertical changes is limited and prone to measurement inaccuracy. Most GPS enabled computers actually have a barometric altimeter which is used to calculate elevation changes and thus gradient fairly quickly.

I was looking about for the sigma yesterday and they won't even ship from Germany - thanks brexiteers! - but a couple of other european shops that seem to so gonna try this one and reviews seem to say it works decent enough.

As above, so long as it shows X reading for Y general slope consistently when I am riding my bike I don't care if it is 'right' according to some external factor as I am only interested for personal data, not to show off to anyone.

I am still quite amazed how such a thing would work and yet to 'believe' through using it but the reports I have read so far give me enough idea that it is worth trying. If they all said 'absolutely rubbish, totally off' I would not bother but the majority report it as being pretty accurate. I read at least one where someone owned a garmin and stated that it was very similar accuracy to that.

 

[Alex321]

Just remember that even the good ones aren't entirely accurate. You will often see a noticeable difference between elevation gained and elevation lost when you have cycled a loop.

And gradients shown will always be a second or two (sometimes more) behind reality.

 

[Dogtrousers]

@presta has hit the nail on the head with that Sigma unit.

But if availability is a problem check out the Van Rysel bike computers at Decathlon. They are similar things and a similar price range and may or may not have everything you want.

Or bite the bullet and set aside your aversion to the letters "GPS" and get a simple GPS unit. GPS itself isn't connected to the grid and doesn't give you navigation, those are add-on bells & whistles. You can find cheap GPS units without those things (again look at the Van Rysel ones at Decathlon). A GPS would be easier to set up than a simple bike computer (no sensors to install, no wheel size calibration) But it would be more battery-hungry, needing frequent recharges, unlike a simple bike computer.

 

[N0bodyOfTheGoat]

If it hadn't been for getting a Lezyne Super Pro in the Chain Reaction fire sale in '23 for ~£25, to replace the careless misplaceplacement of my Mega XL during the final two minutes of sitting on the train in September '22 (must have popped out of jacket back pocket after I was playing with unit minutes before Warminster stop), I would have tried one of the budget Amazon offerings.

You can get Coospo and iGPSport units from ~£40.

I'm almost tempted by the iGPSport 300T that's on offer for £100, for a colour screen and unknown ebike functions https://www.amazon.co.uk/gp/product/B0DLWC6J1Z , but now the ebike is letting me get to hills again, I'm also very interested in some form of "climb pro" function (realtime anticipation of route to give climb details).

 

[Dogtrousers]

I was thinking too that for gradient it doesn't matter at all does it that the altimeter is inaccurate so long as it measures changes from x to y for the gradient, right? so it just has to be accurate to itself?

That's true.

But there will still be a lag. The computer needs to think "elevation was X and is now Y and I've travelled Z since then so the gradient is ... errr" and by the time it's done that it's already out of date. This can be amusing/infuriating if you are riding lots of little ups and downs and the readings appear to be nonsense, but doesn't matter if you're slogging up a big long hill.

 

[bighipspeddler]

but doesn't matter if you're slogging up a big long hill.

That is really all I had in mind. If they are tiny humps then they are insignificant.

It is to get an idea of 'I tackled X gradient previously' to know what I might be able to manage in future. Similar with distance to get a more finely tuned idea of how far I am going each cycle. Good for practical purposes for planning how long it will take and how much a ride will take out of you.

Hmm I have ordered the sigma now from a european retailer before seeing the decathlon suggestions. Fingers crossed.

Just had a look and it looks like the Van Rysel is GPS anyway.

Sure GPS may not be on the internet, but it is still having to communicate with something none local, which is my main issue.

 

[Alex321]

Sure GPS may not be on the internet, but it is still having to communicate with something none local, which is my main issue.

Only passively reading, not really communicating.

It doesn't send anything out at all. Can you imagine the amount of processing power the satellites would need if GPS devices (of which there are millions just in the UK) were sending data back to them? Or the battery power your device would need to send signals.

The ONLY thing using GPS does is to sense the relative positions of any GPS satellites whose signals it can "see".

 

[Psamathe]

Sure GPS may not be on the internet, but it is still having to communicate with something none local, which is my main issue.

Like when you listen to BBC Radio 4 radio using on Long Wave (or Medium Wave) an aerial. Receive only through airwaves.

 

[Psamathe]

That's true.

But there will still be a lag. The computer needs to think "elevation was X and is now Y and I've travelled Z since then so the gradient is ... errr" and by the time it's done that it's already out of date. This can be amusing/infuriating if you are riding lots of little ups and downs and the readings appear to be nonsense, but doesn't matter if you're slogging up a big long hill.

Many hills start gently, steeper bit(s) then level out as you get to the top. So the average gradient will depend on where to define the start and end of the hill (as the gradient increases/decreases).

And look on gradients using online mapping will give a very different gradient form a device on a bike (for any given hill) as the "gradient" is being measured completely differently.

etc.
Edit: My way of using ascent is to only use the number for comparisons with numbers from the same source. I have "calibrated" different regularly used route/ride sources in my mind so I know a ride from cycle.travel (online route creation) of 400m is fine and I know a 30 mile ride with ascent of 300m from my GPS is fine. I've frequently created a ride and checked the total ascent, then ridden the route and seen what my GPS records ascent as (pretty well every day on tour). I've done enough that in my mind I have equivalence between different sources - not an exact "conversion" but a good appreciation in terms of Easy/OK/Hard Work/Find a different route.

 

[Animo]

Does this internet forum not count as part of "the grid"?

 

[Alex321]

Does this internet forum not count as part of "the grid"?

Of course, but the OP did say "as I like to be disconnected from the grid when riding." (my bold). They probably aren't posting here while riding

 

[andrew_s]

I used to have a Ciclosport CM414 cycle computer/altimeter which I found very good, given fair weather.

What @si_c says seems to be the opposite of your claim:

Accuracy of GPS for elevation - and thus calculating a gradient from it - is very poor, satellites look down not from the side so the resolution of vertical changes is limited and prone to measurement inaccuracy. Most GPS enabled computers actually have a barometric altimeter which is used to calculate elevation changes and thus gradient fairly quickly.

A GPS can have two ways of measuring elevation:
Purely from the GPS signal, or
Using a built in barometric sensor (for which you pay extra)

The pure GPS elevations are what is comparatively poor, giving a height that's usually only accurate to 10 or 15 m (i.e. 3 or 4 times the accuracy of the horizontal position).
If there's a barometric sensor, that's pretty much the same as my old CM 414. It's subject to setting drift during the day due to the weather, but is precise and accurate over a short time period.
Usually there's some sort of auto-calibrate function for the barometer, with it averaging the height for 5 minutes or so, then setting the height from that. It does mean you've got to turn on the GPS and leave it out in the open for 10 minutes or so before you start riding, so when at home I generally find it quicker to manually enter the correct height.

 

[figbat]

A GPS can have two ways of measuring elevation:
Purely from the GPS signal, or
Using a built in barometric sensor (for which you pay extra).

Or a device with mapping onboard will use the map data alongside positioning and speed etc. That’s how my device can predict an upcoming climb’s gradient before I get there. Having the map available doesn’t mean you have to view or use it, but the device uses the data anyway.

 

[Dogtrousers]

More recent mapping GPS "know" the elevation at the current location from the map and from calibrated waypoints and do some background skulduggery to continuously calibrate the barometric altimeter so it doesn't drift off too much..

But as the OP only wants instantaneous gradient, not absolute elevation or total height gained so calibration of the altimeter doesn't matter.