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Discussion Starter · #1 ·
It is really aggravating that we have to spend $100 to get our speedo to be accurate. It should come from the factory that way. I was riding my bike at an indicated 74 mph and EVERYBODY was passing me. I went by a roadside radar and it said I was going 65! I was pissed! :banghead

I have always thought it to be very dangerous on a motorcycle to go too slow on an interstate. It is just plain suicide. I've always liked to go a little faster than other traffic for the most part. I feel more in control when I am doing the passing and am able to watch people in the cars and anticipate what kind of stupid-ass move they are going to make.
 

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The way I see things, it's basically impossible to get a speedo on a bike to be accurate 100% of the time.

A manufacturer supplied 180 tire can vary by as much as 10 mm in width, and 5 mm in depth. Meaning your rear wheel might be 5 mm greater in radius depending what kind of tire you're using. This will throw off a speedo. The there's the fact that the wheel will deform at higher speeds further increasing the radius and affecting your apparent speed.

There's also all the gearing issues that come up as people start changing sprockets and the like.

Then you need to take into account that the radius of the tire when you're leaned over is smaller then the radius when you're going straight (you're rolling across the side of the tire where it's a smaller surface). So your speedo will technically read slower when you're leaned over.

Also bike tires exhibit greater wear in the middle (unless you're blessed enough to live in a twisty enough area that you don't get flat spots). Your speedo will show slower as your tire wears in the middle. I think that it'll show slower, it's been a while.


So basically, if you want to be going slightly faster then traffic, go slightly faster then traffic.
 

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Don't know about anywhere else but it's law in the UK that the standard speedo on a vehicle should read over from the factory. It's done for good reason to avoid legal arguments where someone gets stopped for speeding and claims that according to their speedo they were legal. If it's in standard factory trim it will never happen that way.

As Sev said, if you like to go slightly faster than the traffic around you then just ride faster. There will always be people around you breaking the limit anyway so you just take your chances. If you're not being stupid and are observant enough there's no reason why you should get caught by a speed trap.
 

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This pisses me off too the other day im on the highway where the limit is 100, im going the same speed as everyone around me, i look at my speedo and im doing 156! wtf???i know their inacurate but thats rediculous.

everywhere i go now i have to try as hard as i can to keep it at the limit, on a sportbike thats not easy especialy on one with a fucked up spedometre.like il be in an 80 zone trying to do the limit, but i look at my speedo and im doing 110.having to look at the speedo every 5 seconds constantly looking for cops and not beign able to use even like 30% of my bikes power in the street is taking the fun out of riding, so im getting out.
 

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This pisses me off too the other day im on the highway where the limit is 100, im going the same speed as everyone around me, i look at my speedo and im doing 156! wtf???i know their inacurate but thats rediculous.

everywhere i go now i have to try as hard as i can to keep it at the limit, on a sportbike thats not easy especialy on one with a fucked up spedometre.like il be in an 80 zone trying to do the limit, but i look at my speedo and im doing 110.having to look at the speedo every 5 seconds constantly looking for cops and not beign able to use even like 30% of my bikes power in the street is taking the fun out of riding, so im getting out.

That doesn't sound like the bike's fault. And unless you've changed gearing there's no way in hell you're doing 100, and it reads 156.

*Edit* Oh man, you live in Toronto? Dude, the people around you are probably doing like 135-140km/h. So you reading 156 isn't that unreasonable given that most bikes are out by 8-10%
 

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This pisses me off too the other day im on the highway where the limit is 100, im going the same speed as everyone around me, i look at my speedo and im doing 156! wtf???i know their inacurate but thats rediculous.

everywhere i go now i have to try as hard as i can to keep it at the limit, on a sportbike thats not easy especialy on one with a fucked up spedometre.like il be in an 80 zone trying to do the limit, but i look at my speedo and im doing 110.having to look at the speedo every 5 seconds constantly looking for cops and not beign able to use even like 30% of my bikes power in the street is taking the fun out of riding, so im getting out.
I understand where you're coming from with the cops and stuff taking the fun out of riding. It's one of the reasons why I've moved down to a 600 - at least I can have a little more fun with it than something bigger.

As regards the speedo you might want to do what I used to do with older bikes and cable speedo's. As soon as I got a new bike I used to work out speeds at various revs in different gears. I still do it now just in case the electrics get dodgy. Not 100% accurate but at least you'll have some idea what speed your doing. Get a mate to help you by riding / driving at set speeds and just move through the gears to find easy to remember gear / rev combinations for set speeds.
 

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It is really aggravating that we have to spend $100 to get our speedo to be accurate. It should come from the factory that way. I was riding my bike at an indicated 74 mph and EVERYBODY was passing me. I went by a roadside radar and it said I was going 65! I was pissed! :banghead

I have always thought it to be very dangerous on a motorcycle to go too slow on an interstate. It is just plain suicide. I've always liked to go a little faster than other traffic for the most part. I feel more in control when I am doing the passing and am able to watch people in the cars and anticipate what kind of stupid-ass move they are going to make.
Yeah, last night I was coming up on one of those roadside radars and it was saying I was doing 45 mph, I was watching my speedometer and it was reading 53 mph...I had already read this thread and thought I'd let ya'll know about my experience.:banghead
 

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Well I'm glad it's off a little, as long as you know it's not that big of a deal, plus it kept me from getting at least one speeding ticket so far.
 

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Discussion Starter · #10 ·
Well, Speed limit is 70. If you go 76 or so they won't pull you over but your gonna get it if your doing 80 or more. So it would be nice if it were a little closer than 10%.
 

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Mine was off just under 7%. I held it at 90mph and timed myself for one mile, and I figured up I was only going 84-ish. At 90mph it should take you 40 seconds to go one mile, whereas it took me somewhere around 43 seconds. Bought the ole SpeedoHealer and fixed it right up. Sucks to have to spend more money just to have an accurate speedometer tho.
 

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:tard are really all speedos that inaccurate ? That's retarded.. Ill have to check how mine's doing. But I wont get my bike before Thursday!!! :banghead
 

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:tard are really all speedos that inaccurate ? That's retarded..
Basically yes - some degree of difference from model to model but about 10% over is the norm.

Don't see what's retarded about it myself. As I said in my earlier post it's done for a very good reason. When you ride or drive you know your speedo is about 10% out so you have a reasonable idea of what speed you are doing.

Personally I don't understand the need to know the exact speed that you're doing for road riding. At the end of the day you should be riding according to the conditions anyway so in a 50 your speed could be much higher or lower depending on many factors. In terms of not getting done for speeding then factoring in the 10% it's fine to be doing an indicated 53 / 54 ish. It's gonna be a very picky cop that'll stop you if your true speed is 51 and I don't feel that I MUST do exactly 50 whilst trying to avoid getting stopped in a 50 limit. Hell if it's only 48 I'm doing I'm really not going to sweat about it.
 

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Maybe its not such a big deal as I seem to think. I guess it's only because I always assumed my speedometer to be pretty accurate. But I think that you shouldn't have to get a speedohealer to adjust your speedometer's accuracy on a stock bike... they should be able to make it reasonably accurate when they manufacture the bike.
 

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Maybe its not such a big deal as I seem to think. I guess it's only because I always assumed my speedometer to be pretty accurate. But I think that you shouldn't have to get a speedohealer to adjust your speedometer's accuracy on a stock bike... they should be able to make it reasonably accurate when they manufacture the bike.
Don't forget that the tire wear as well as other factors play into effect. The more wear on your tire the most inaccurate the speedo. Even with the speedohealer, you still have to make adjustments over time. GPS is really the only truly accurate measurement.
 

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But I think that you shouldn't have to get a speedohealer to adjust your speedometer's accuracy on a stock bike... they should be able to make it reasonably accurate when they manufacture the bike.
They can, but as I said in my first post this isn't about the ability of the manufacturer to make them more accurate more to do with legislation (DOT, TUV and no doubt something over there in the good 'ol US as well) specifying the need for a stock speedo to read over by a set amount. For the benefits of mass production they go above this so that each one doesn't need to be accurately checked. Plus of course they have to take account of factors such as tire wear as antihero points out.

You can also blame the US of A and it's lovely lawsuit culture for some of this as well. Imagine the scenario where the speedo's are made more accurate and then good old John Doe (with nothing better to do) proves that his speedo was reading under and so therefore the manufacturer is liable for him having got a $50 speeding ticket. Add on stress, loss of earnings to attend court, court costs, suffering to his cat where he shouted at it because he was annoyed at getting a ticket, the costs of his divorce which only happened because of an argument about the ticket etc. etc. and the manufacturer is looking at a hefty bill. Once he wins his case within a week a thousand lawyers across the land will be offering no win, no fee representation for disputed speeding fines and next thing you know you lot will be paying the same amount as us in the UK to purchase your next new bike :rofl I'll accept that it reads around 10% over thanks.
 
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