Modern Vespa

I have a 2023 GTS 300. I noticed my speedometer is off by at least 5mph. any way of fixing this. I was using a GPS but I don't how accurate that was so I started speeding through the speed traps NYC has. You get a ticket in the mail after doing 36 mph. When my speedometer is reading 40mph the camera doesn't flash ( I'm assuming I'm under 36mph) anything over 40 mph the camera is going off.

normal for all vespas, do the maths in your head. note: is not a fixed 5mph instead it's the speedo exaggerating by approx 9% ie different error at different speeds

or for pre-2023* use a different abs tone wheel (apparently doesn't work for 2023. personal hunch for 2023 might need to replace both front and rear not just rear)
eg
https://www.scooterwest.com/abs-overdrive-tone-timing-wheel-disc-rear-gts-gtv-hpe.html
or


* I know yours is 2023 so I'm only mentioning this for completeness

Edit: extra note, the above mentioned tone wheel will make the speedo correct but will make the odo and trip and avg mpg etc shown on the dash wrong.

I just assume it is 3-5 MPH faster than I am going and adjust. It seems to just be a Vespa thing.

It's my experience that almost all motorcycles, as well as scooters that I've owned (my current '20 Vespa GTS, and a handful of Suzuki Burgman 650's), are universally 'optimistic' in their speedometer readings by 5-10%, and more often than not, closer to that 10% than 5.

I've had the correcting tone ring from Scooterwest since last spring, but haven't been in much of a hurry to install it. Maybe one of these days.

For now, with my GTS 300, I just mentally deduct 5 mph off of it's speedo reading at anywhere from 50 mph to 75 and just leave it at that. It's close enough for practical riding, and should keep me from attracting any speeding tickets

Before replacing the very worn rear tire on my '22 Triumph Rocket 3 this past week, It's speedometer would have to be reading 82-83 mph to be doing an actual 75.

Apparently, part of this highly erroneous speedo reading was due to the, when new, 50mm rear tire height being worn down to less than that, and throwing off it's 'normal' speedo error even more.

Interestingly, when I replace the original oem Avon with a slightly oversized 240/55mm Bridgestone Exedra, at an actual 75 mph the speedo is reading no more than 77-78, reducing it's speedometer error by at least half of what it was.

it's a feature, not a bug.

You're correct. Get used to it and factor it in. I recently asked a BMW dealer if the speedos are accurate on the GS. Nope. They are a few mph off too.

Sometimes, my Vespa's 'overly happy' speedometer annoys me and I gripe about it and think that I need to find a way to make it more honest....but then, I would ruin my little dream world of thinking that I'm running along at 65 when I'm not, and it runs just SO sweetly at that hyped up number that I kind of hate to pop that balloon.

This. Speedo optimistism (reading higher than actual speed) is damn near universal in the world of two wheels.

I was trying to figure out by what percentage the speedometer was "optimistic" on my motorcycle so, having nothing else to do one chilly morning, I rode around making video of the speedometer and a gps app at various speeds. Later, having nothing else to do, I got completely carried away and edited it all into a youtube video.

The results are not what I expected inasmuch as there is no consistent percentage by which it is off. For instance, it is off by 5 mph at 65, 70, 75, 80, and 85, but is 2 or 3 (or 4 or whatever) mph off at various lower speeds.

A side note on the video, should you decide to subject yourself to it, is that I spent a ridiculous amount of time making the soundtrack, which I determined needed to speed up constantly as it goes along. Additionally, I tried to create a Shepard Tone as well, which is an interesting musical thing that sounds like it's constantly rising. The music became the focus of the project and I'm still not sure if it worked, but I learned a lot doing it. Such things happen when one is self-unemployed.

I would think that, back in 'ye olden days' of rotating speedometer cables in direct mechanic connection to the front wheel and speedometer heads, that any error would be a consistent percentage in that a 10% 'optimistic' error would show 2.5 mph (27.5 indicated) over an actual 25 mph, 5 mph over an actual 50 mph (55 indicated), and a full 10 mph error at 110 mph indicated, for an actual 100 mph.

Perhaps not so with modern electronic speedometers where there isn't any rigidly mechanical mechanism that operates the speedometer, allowing for an inconsistent or variable error amount, especially if it's deliberately programmed-in by the bike's manufacturer.

Just a thought.

Mine reads about 12% fast and I got tired of doing math calculations while I was riding. "Let's see, if I want to go 60 I multiply by 1.2 and that comes to 72.".

I bought a GPS speedometer and hot glued it to the center of the instrument cluster. Less than $15 and it is exactly accurate.

Both mine and my wife's 2021 GTS Super's speedo is off by about 10% at lower speeds and 7-8 mph at higher speeds. Using Waze to get my actual gps speed, i have to do 62 mph (per my speedo) to actually go 55 mph.

You can also get a slight correction by upsizing your front tire.

On my Yamaha SMax (I know, I know), I moved up from 120/70-13 to 130/70-13 and my speedo error was nearly eliminated. Comparing my Speedo to my Garmin GPS, it was either exactly the same or +1 mph.

I've seen similar results on my old 2009 GTS, but don't recall the exact correction. Will likely do this on my current 2007 GTS next time I need a front tire.

Most excellent!

Thanks! If anyone wants to make one with a scooter I'll send the file. It will, however, cost you .00000000002 cents per play.

I'm not sure how to un-learn this information. I was blissfully riding around thinking I'm an excellent driver for never getting pulled over for speeding on my Vespa. Now I'll subconsciously speed up by 5 mph.

This does however explain the salty looks I get when someone passes me while I think I'm doing the speed limit.

SIP does offer a 2023-specific tonewheel.

Whether buyers in the US actually receive it, is another issue altogether.

Personal experience, even if it doesn't arrive, SIP will just say "well we put it in the box so it's not our problem."

Ah, Germans.

this is true.

Wow that is horrible. I mean that's happen to me a few times. I just call the credit card company and dispute the charges

When I ordered my 6000 mile service kit (really DO need that new belt, ya know) from Scooterwest last week, I also had them send one of these nice mirror stem phone mounts with the idea that I would use it for that cheapo $15 digital GPS speedometer I bought last month, not that having a more accurate speedometer is a huge priority, but it would be nice to know what my speed actually is every now and then.

When it first arrived, I tried out the cheapo $15 GPS speedo in our Ford F-150, which as far as I can determine, is no more than 1 mph 'off' at normal highway speeds.

The $15 cheapo GPS speedo reads about 1.0-1.5 mph higher than the Ford's speedo, and 1.5-2.0 mph higher than my phone's GPS speedometer, so It's reasonable to say that, at it's worst, it's 2.0 mph higher than 'actual' at 70-75 mph.

In a perfect world, I would prefer zero error, of course, but 1.5-2.0 mph 'optimistic' isn't too bad, when considering that the vehicle's factory speedometer is 'off' 5.0 to 7.0 mph at the same actual speed.

The $15 digital speedometer feels like a cheap piece of crap, quite toy like, with a casing of brittle black plastic, and with it's weight that feels about the same as an unsalted soda cracker, it doesn't impress one as a particularly durable thing....but the damn thing works, for how long is anybody's guess, but it works...and, you know, $15? What's not to like?

The mirror stem phone mount is a quality item, mounts to the stem easily and seems secure. I had been trying to figure out an acceptable way to mount the cheapo GPS speedometer without resorting to gluing, adhesive mount Velcro, or anything that would involve applying anything to any painted surface of the bike. The mirror mount was $40, but as a well-designed and well-made problem-solver for my use, it was worth it. Altogether, a quite tidy solution for mounting stuff to my GTS, though I still need to figure out a neat power cord route from the 'cubby hole' to the unit.

For the cheapo speedometer, I will still need to modify it a little so that the phone mount can have a more secure grip on the speedos smooth, kind of oddly shaped case, but it shouldn't be a big problem.

Of course, I could just stick my phone into the holder and use It's GPS speedometer, but I'm not all that keen on having a phone staring at me all the time when I ride, and it's relatively large and heavy...and then there's the ever-present possibility that someone will call me, and when I'm riding any sort of motorbike, I'm in my own little world and 'off limits'.

I hope you have better luck with the mirror stem phone mount than I did.

I couldn't keep my mirrors tightened down with a phone mounted. I'm not sure if it was the extra weight causing vibrations or if it was wind resistance.

I probably won't use it to hold a phone very much, mostly that small and much lighter cheapo GPS speedo, which isn't nearly the barn door for wind resistance the phone would be.

If I mount the holder as close to the threaded end as possible, the wind would have limited leverage to loosen the mirror.

I'll just have to see how it goes though. Might work, might not.

true for older gts but on current you need to change the rear instead. with hpe (and probably earlier abs gts?) the speed is from the rear wheel abs tone ring unlike older where it was mechanical cable from the front wheel.

On my iPhone I can easily set a focus to complete Do Not Disturb where all calls are sent to voice mail. Reality though my DND setting will allow my husband and kids to call. Even if I don't answer I can check message in case it is important when it is safe to pull over and check.

My phone is with me when I ride, but it's always exiled to the interior of my backpack (which I always wear these days, regardless of which machine I'm riding) along with my baseball cap.

We never had kids, so they won't be calling me, and thank heavens, our two cats haven't figured out how to use a phone yet, so other than my wife, no one of immediate importance will ring me up while riding.

I've had the speed-correcting replacement tone ring for months, I ordered it along with the oil sight glass engine cover, but I've just been too lazy to tackle the installation of it yet, though I managed to get the engine cover on ok.

Yeah, Germans! 😉

You had problems with shipping from SIP?

Due to European regulations, no commercial merchant located in Europe will ship without proof of shipment (tracking ID). According to European law, merchants must prove that the package has been shipped/arrived at the customer.


"Where is my parcel?
SIP Scootershop generally sends your parcels with four different courier services, DHL, UPS, FedEx or, for large deliveries (frames, lifting platforms etc.), Dachser. As soon as your parcel is ready for dispatch, you will receive an automatic dispatch confirmation from us by e-mail, in which you will find more detailed information about your parcel, including tracking information . You can find an overview of your orders and their status in your customer account under "My orders".

I have ordered via DHL Wolrdparcel and the delivery is overdue.
On average, over 800 parcels leave our warehouse, which is why we only work with reputable courier services (DHL, UPS, FedEX, Dachser). With the international DHL service Worldparcel Economy, DHL offers a low-cost service for worldwide shipping. This is made possible by the transport routes sea, road and rail. We ask for your understanding that tracking and tracing is only possible to a very limited extent and that the standard delivery times can sometimes deviate considerably.

An investigation on the part of SIP can only be requested after 6 weeks from the date of dispatch. During this time, our hands are tied and status updates are not possible.

However, you are welcome to contact DHL customer service directly on +49 18063453003, quoting your tracking number!"
https://www.sip-scootershop.com/en/page/faq_27?tab=2_delivery-shipping

I just subtract 5mph from indicated speed to get "close enough" around town.

Man, I want that sight glass engine cover SO bad. I'm quite jealous.

In my humble opinion, it's definitely a worthwhile and sensible addition to the GTS 300 HPE, and you're knees will thank you.

I've spent a LOT money on worse things (though my $10.60 trombone isn't one of them).

The box arrived destroyed and part of my order was not inside.

They absolved themselves of responsibility by saying "well we put it in there so it's not our fault."

Meanwhile DHL won't work with the recipient, the SHIPPER (i.e. SIP) is their customer. SIP is responsible for filing the insurance claim, and despite being sent photos of the destroyed box as it arrived (one entire seam had been torn open) they still said "too bad we put it in there not our problem."

But you're certainly welcome to assume you know anything about the incident and post completely unrelated "solutions" that neither apply nor help in any way.

It was not a solution… I'm just asking!

Nothing is further from my mind than wanting to be helpful to you (in the future).

What i… give you positive for this inappropriate post?

Sorry anyway if you had bad luck in this case.

Other posters are correct in pointing out that even GPS isn't 100% accurate for speeds. They are best in lateral position. Vertical position is not as good. And since we are riding in a 3-D world, the calculations are always a bit off. It's quite a bit of engineering to get positions of less 3m of accuracy, from a source in space! But to do it while on the move, that is even more difficult. There are GPS systems (think Trimble) that are accurate down to cm level, but I doubt they could maintain that level of accuracy while moving at 50 mph.

One way to test is to use the roadside radar guns that say "Your Speed Is: XX". They aren't exactly 100% accurate either, but they'll give you a good idea.

My iPhone 13 told me that when I am going an indicated 50 mph (another issue is parallax error with the analog speedometer), I am really only going 48 mph. I'm happy with this. 4% error at that speed is really good. My car is about that much off too. If it is going to be wrong, I'd rather the speedometer on the vehicle be a little optimistic. That might get you out of getting a ticket. I know it saved me a time or two in my car!

Oh, by the way, when your tires are at different pressures, the accuracy is affected. And if you get different tires, different brand or model tires, that'll affect it. And of course, if you choose different size tires, that will affect it. The manufacturers of motor vehicles are only required to provide a speedometer. There may be an ordinance requiring some % of accuracy, but maybe not.

This is a common misunderstanding of how GPS receivers calculate speed. Most people just assume the most obvious speed calculation -- the distance between two successive locations over a fixed time interval. But GPS receivers (well, most of them) use a much more clever way to calculate speed.

The preferred way for a GPS receiver to calculate speed is by observing the doppler shift on the GPS carrier frequency from multiple satellites. Position is irrelevant, and therefore vertical travel is irrelevant as well.

Generally speaking, GPS-based speed readings should be good to within about 1MPH.

(Here's a reference if you don't believe me).

One could attempt to calculate speed in the obvious way -- from successive location readings. And I'm sure some GPS receivers -- especially "soft" receivers like those in phones -- might do something like this. But this technique is considered inferior, for reasons that you've highlighted in your post.

TLDR: phone gps is good for nav but not great for accurate measurements.

Please no arguments about phone brands.

sadly in phones they don't do as good a job as expected (pro gps as used by surveyors etc is a different story). In some of my recordings of my supertech telemetry vs gps, I've seen the gps speed jump in different types of scenarios.

firstly I've seen it occasionally jump up a bit during straight line constant speed when compared to the wheel speed. only a few kph but still a distinct jump. first time I saw this in my recordings was in open flat country - no trees or mountains so no excuses. this is not common but does happen.

secondly when it fails to report updates for a couple of seconds it then does a speed jump when it realises that it's actually moved and has to make up the distance in a very short time.

also when corning it predicts where I am about to be if I had continued in a straight line and reports me well off the side of road. so this results in it calculating more distance covered in the same time period. (might be only modern android - need to test older phones).

so would I trust it for an accurate speed? only when steady speed in a straight line and averaged over at least 10secs. But quite fine for general purposes.


PS I can produced samples of my recordings if really needed but that should be in a new topic as would no doubt be a long discussion.

and a little extra:

phones apps don't usually use pure gps. instead they report based on a combination of gps and info from nearby cell towers and wifi etc. this complicates the whole story

Agreed that phone-based GPS is probably not a very good example of GPS Best Practices. And even though I've long since lost any hope of convincing people otherwise, I will continue to beat this drum until I die: I don't think using a phone (of any brand) is a valid substitute for a dedicated hardware GPS receiver when it comes to navigating on two wheels.

So what your saying is go as fast as I can when I see that cop on the side of road scanning people speed.

Whenever someone asks me how fast my scooter can go, I tell them speedometer speed, not real speed.

Interesting that SIP entered the conversation. I'm in the process of installing one of their farkle dashboards amongst other electrical gizmos while everything is apart, after finally doing the 632 mile service on my GTS. Along with the extra info presented you may adjust the speedometer to match your GPS on a long clear stretch, akin to a speedo healer. An option for those inclined.

Vendor criticism is verboten by rules. One has to be accurate and persistent when dealing with SIP's shipping practices. Specify UPS or FedEx where the recipient can open a trace. Use a payment method which provides control should the goods not be delivered in a timely fashion. I was pleasantly surprised with a shipping upgrade from SIP last week after pointing out the inconsistencies in their communications and policies. This is a huge improvement over the order placed with them five years ago.