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Intended speedo error?

Discussion in 'Mechanical & Technical' started by kyler jenson, Dec 1, 2017.

  1. My brother and I go around with this subject every so often. He says speedos are off by 8% to keep people slower. Same in cars starting in the eighties. I go a hun. and he says it's only 92.
    Some of the speed readers I go by will say 2-3 miles slower than my gauge. So the speedo reads slow and the odometer shows correct? How stupid. Don't ya want a accurate gauge? Is the error the same throughout the gauge range... Makes me want to get into the gauge and move the needle! HA ha. I know, don't even try.
  2. This is on motorcycles only as far as I know. It’s a liability issue on the manufacturers part. I would have to do some google searches. It was either in the US OR Canada but a personal sued a manufacturer because their speedometer was reading slow and they got a ticket. Since then the manufacturers have put in an intentional positive error. I had the fact numbers from tech school for BMW and Triumph at some point by I don’t recall exactly what they were but they both error close to 10% at 60mph. However the error is not 10% at 100mph it changes across the board.

  3. Thanks. But, isn't a positive error in fact going to be slower than actual as well? (smoke from ears) How could a manufacturer be held liable for correct readings, when operator chooses to ignore? (more smoke and sparks)..KJ
  4. It’s nearly impossible on a motorcycle to guarantee exact speedometer speeds. Tire radius varies. Even within a specific model of tire if it comes from a different productions site it can have a different radius also motorcycle tires use to grow with speed before we got radials in the 90s. This is also why every manufacturer has a very specific set of approved tires. Sometimes to the point that the approved tire is only available from the bike manufacturer. I’ve seen that on a couple models over the years when a new bike launches.

    When I say positive error I mean the speedometer reads higher than actual. The manufacturer was held responsible for incorrect readings. The speedometer read slower than actual.