digital speedometer

Discussion in 'General Questions' started by drukstanas, Nov 9, 2015.

  1. drukstanas

    drukstanas New Member

    Hi, I have weird problem. Once i start up the engine speedometer instantly shuts off. It works perfectly when i do not use motor. Does it happens with all digital speedometers? I tried with two of them, both had same problem. I think it happens because of vibration.

  2. butre

    butre Well-Known Member

    You need a wired speedometer. Electromagnetic interference kills wireless ones
  3. drukstanas

    drukstanas New Member

    mines is wired
  4. Neufcruz

    Neufcruz Member

    Since your on the subject. Do the old school needle speedometers work? the ones that conect to the front hub. Would this work on a luya rim with disk brake? I like the idea of digital and get all the other functions but sort of like the old simple look.
    Any experience or suggestions are appreciated.

    Thanks in advance

  5. The_Aleman

    The_Aleman Active Member

    Some digital speedometers are more affected by EMI/RFI from small engines than others. Some engines produce more EMI/RFI than others, as well.
    I have seen speedometers work fine with one engine but not other one of the same type. It's almost always caused by the engine's magneto.
    The windings aren't particularly consistent, and shielding is pretty much non-existent. If your digital is wireless, the problem may be exacerbated.

    You can take several steps to get your speedometer working:

    1) Isolate the speedometer from the frame the best you can. Since your engine is using the frame as a ground, it can cause some interference in a digital speedometer- wired or not.
    Start by insulating the frame where the speedometer head mounts and also the fork where the pick-up mounts. If there are any cables, shield them from the frame.

    2) Install a ferrite core noise suppressor on the plug wire. These are inexpensive and snap right on. It may be hit or miss whether it works well enough, but I've had good results.

    3) Run a resistor version of a quality spark plug (small threaded cap). You may also need a plug boot that works with such a plug. Make sure it's good quality, I recommend NGK.

    All of the above should get your digital speedometer working. I've been running digital speedos for over 20 years and have seen some weird behavior from them!
    The analog needle speedometers just don't last on our bikes. Believe me, I've tried many. Digital all the way!
  6. KCvale

    KCvale Motorized Bicycle Vendor

    I like the old school speedo's.
    I can't read those digital's when I'm riding, especially in the bright Phoenix sun.
    That goes for the Tach on this bike too.

    Just 1/2 a glance down and you see the speed easily.
    20 mph is straight up, the red zone starts at 30 mph, this bike could almost bury the needle.


    They work on 26" wheels only, ~$30, work with a left disc brake, pretty accurate but not known for their longevity.

    Still though, they look cool and easy to read, all I need ;-}
  7. butre

    butre Well-Known Member

    kc, I had one of those speedos and it wasn't even a little bit accurate. the needle goes crazy after 30 km/h and if you pegged it once it would never return to zero again
  8. The_Aleman

    The_Aleman Active Member

    That's what every single one of those cheap analog speedometers I've tried did. Once you go over a certain speed the thing goes to crap.

    The only modern analogs that seem to work well are the Whizzer speedometers. My brother has had one for over 5 years, still works great.
  9. KCvale

    KCvale Motorized Bicycle Vendor

    I know, I have toasted a couple myself, those cheap analog speedo's are not known for reliability at enhanced MB speeds, certainly not accurate enough for high speed exact speed readings, but really still ideal for those that run in that 25-32 mph basic MB range and want an easy way to glance down and see speed for ~$30.

    I would really like to be able to use scooter analog speedo but it's all about the gearing ratio from the tire rotation to match the needle and scooters that have small diameter wheels.
  10. butre

    butre Well-Known Member

    do what I do for adapting speedos, just print a new face plate. way easier than changing the gearing
  11. The_Aleman

    The_Aleman Active Member

    I've seen those cheap analogs break before 25MPH. Maybe some here have had luck with cheap analogs, but I sure haven't. If anything they've gotten worse over the years.

    Back in the 1980s those cheap analogs might last a few months, in the 90's maybe 1-2 month. I broke one first day in the 90's while drafting a car on a bike going 35MPH.

    They are cool, being analog, but I wouldn't call a cheap analog "really still ideal" at _all_. They are built like junk, not worth anything at all.
  12. butre

    butre Well-Known Member

    any old cable driven speedo can be made to work. doesn't even matter what it comes from, a car speedometer can easily be made to work. I saw a perfect speedometer from an Alfa Romeo that went up to 80 mph on ebay earlier today
  13. 2old2learn

    2old2learn Member

    I've been very pleased with the App: Bike Brain on my IPhone 6+. Large, easy to read, lots of data, press a button and I'm on a moving map screen. Records each ride. Got to have a phone with me anyway. Set it up so my wife can pull up a tracker to see where I'm at anytime she wants to. So when I'm hanggliding, cycling, backpacking or anywhere else she can at least verify where my phone is. Married for 37 years, nothing to hide!
  14. KCvale

    KCvale Motorized Bicycle Vendor

    Sure, just make a new scale! But can you elaborate on what you have used to connect it to the wheel?
    Can it just directly attach to a cheapo bicycle axle/spoke cable drive fitting?
    I thought there might be different size and connection type cables.

    Again, cable ends and wheel part connection would really help using an accurate analog speedo that go to high speeds and still be able to glance down and see as at 50mph on a bicycle you don't want your attention diverted long in city traffic.

    Maybe someday we will all have to have a charged smart phone just to see how fast we going in a car or just work my toaster ;-}

    Just teasing ya 2old, sounds like a 'virtually' free way to know your speed at a glance.
    I'm just an analog guy when it comes to machines, no batteries required.
  15. butre

    butre Well-Known Member

    they're all screw on, and from what I've seen the cables are always the same size. screw flange can be different though, but you can usually just epoxy it to a regular bicycle axle/spoke speedometer fitting, or you can just use a front hub off a puch, which already has a speedo fitting.
  16. KCvale

    KCvale Motorized Bicycle Vendor

    Thanks butre, I keep an eye open for something local and give it a try as I have speedo parts.