has anyone fitted a pedalbike speedo to motorbike?

ronnieringdin... · Nitrous Nuisance Joined: 04 Jan 2006 Karma :

hello chaps
ive built a streetfighter r1 im planning on fitting a pedalbike speedo im not sure which one to get coz theres bloody loads to choose from has any one ever fitted one ? what problems should i expect ?
thanx for any info ronnie

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Yes. Go for a wired one (due to interference.)
Cheap tescos one would start showing half or third speed from around 50mph.
Cat's eye one has been on my zx9 for maybe six or seven years. Tested to 150mph. As it's pretty old now, the specific model probably won't help you.
Remember you /should/ have a back light. I never bothered, but coming up to gatso's at night you have to catch street lighting just right as you pass it to see the speed, which is irritating.

Frost · World Chat Champion Joined: 26 May 2004 Karma :

From a pure computing perspective there is no way of being certain a bicycle one will work at speeds about 40mph. Chances are it will work, but how accurate is going to be a bit random. I think vehicle speedo's have laws to follow they are something like:
Must not under read speed
May not over read by more than 10%

On a bicycle an under read or over read of 15% wouldn't be noticable or illegal. I would find a dedicated street fighter community with some expirence in doing this and ask them if they know of and specific ones that work.

Ichy · World Chat Champion Joined: 15 Jul 2005 Karma :

I had one from Aldi that worked fine except that it suffered a bit of lag when accelerating. On wot it went from 0 straight to 40. Main thing to think about is where you mount the sensor and magnet. I drilled a recess into the front disc and used alridite to hold it in place.

I was going to fit a small led as a light but never got around to it. I think someone on here suggested painting half the led with nail varnish to stop it shining in you face.

Ichy · World Chat Champion Joined: 15 Jul 2005 Karma :

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

In my experience bicycle ones tend to be more accurate as you measure the tyre yourself - the rest is very 'simple' maths, or should be!
Generally show as much more accurate when tested with a GPS compared to standard vehicle ones - as I say, only problem is that cheaper ones seem to start to 'miss' every other rotation, or whatever.

. · Renault 5 Driver Joined: 18 Feb 2008 Karma :

I fitted a halfords wired unit (£10) to compliment my standard speedo which started to flicker eratically whenever above 40mph.

I used a gps device to calibrate it so its probably about as accurate as almost anything else out there.

However I did have to buy a larger neodymium magnet (£2.50) as the standard magnet supplied wasn't powerfull enough to cover the distance between it and the pickup unit when fitted on my bike.

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Where did you get the larger magnet from out of interest?
That may have cured the issues with the cheap one, but it may have just been a case of not being able to differentiate the signal at that speed.

Frost · World Chat Champion Joined: 26 May 2004 Karma :

The issue is likely related to the devices timings at it only being able to pick up one pulse every 10th of a second, then when you give it a pulse twice frequency that it misses every other one. Fitting a bigger magnet would help if it were just simply moving too fast to have a magnetic effect, but if it's genuinely missing every other then that isn't the problem.

neatbik · World Chat Champion Joined: 27 Jun 2007 Karma :

I did it on an RS125 i had, was much cheaper than replacing speedo drives every 5 minutes...

The one i used was £10 from Halfords, worked a treat. Thumbs Up

ronnieringdin... · Nitrous Nuisance Joined: 04 Jan 2006 Karma :

what a wonderfull response cheers chaps

Alexio · World Chat Champion Joined: 27 Aug 2009 Karma :

Does the cheap one from Halfords have a backlight? My normal speedo has no back light any more and I can't be bothered to open up the clocks to replace the bulb. More than that I'm starting to think the speedo isn't all that accurate. Yesterday I was following someone in their car down a very large hill. My speedo read 60MPH exactly and afterward they told me I had hit 70MPH in keeping up with them (and I was at full throttle, which would sound right for my bike).
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neatbik · World Chat Champion Joined: 27 Jun 2007 Karma :

No mate, it didnt have a backlight. Im sure you could knock something up with a LED though Thumbs Up

Ditto · Nearly there... Joined: 26 Sep 2009 Karma :

Alexio · World Chat Champion Joined: 27 Aug 2009 Karma :

lauriematt89 · Derestricted Danger Joined: 23 Jan 2010 Karma :

the needle went on my honda, so i bought a cateye velo5...one of the most basic speedos you can buy but they are really reliable

instead of mounting it to the fork...and using spacers...i managed to attach it to the mudguard mount...fits a dream

only downside is i cant see what speed im doing at night. doesnt matter though cos im not a fast rider Laughing