Compass for bike
 

I'm after a small basic compass to fit on the screen of my bike, any one know where to get something in the UK? Or do you think the bike electrics will effect it too much?

I believe that you are supposed to use a compass well away from any large metal objects, such as cars or bikes, as it affects the bearings. Having said that, my mate's got one in his fiat panda!



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Sean

I've had no luck getting a compass to work on my KLR: Too much metal. I do have one attached to the cross bar. It detaches easily and I use it away from the bike for an acurate reading.

Ah that also answers another question thanks - nowI know why people have £200 GPS systems rather than £2 compasses!

I've seen (magnetic) compasses being used in planes, which to my knowledge fall in the category "large metal objects".

The deviation incurred by the metal is corrected using small screws / magnets, equal to the deviation correction on a more expensive compass. So i haven't looked for car-compasses which can be corrected, but they should be around. However expect to pay more than 2 quid for one, as a decent handheld compass costs around 20 pounds.

Hope this helps.

On ships the correction of the compass for (magnetisable) materials in the vicinity indeed works with small magnets, mostly done by specialised people. This helps to take away the largest deviation. Then, what is left (usually in the order of max 5 degrees) you'll have to read from a table that is provided by the specialised person, the correction depending on the course you are going at that moment.

The problem on motorised vehicles is the fact that the magnetic field lines around it are far from constant. Switching on your headlight will already have an influence, also because of the low voltage (12 V) and therefore stronger currents all producing stronger magnetic fields. Things like alternators also tend to produce strong magnetic fields.

So, a compass mounted on the handlebar would never be really reliable. I would advise the suggestion in the other reply, have it at hand, but before taking your bearing walk away from the bike (also when the engine is not running!).

Auke

Ok I will see what I can obtain locally and try different positions on the bike with engine running/not running and let the 'board know. Thanks for all for your advice

Buy a cheap "scouts compass" and put it in the map case on your tank bag. Worked fine for me. This mount also reduced vibration in the compass, but you have to find a position where the compass would be fairly horizontal. Great alternative to GPS. http://www.horizonsunlimited.com/ubb/smile.gif

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Dag
http://RocinantesTravels.com

Great idea will try it when I can find a suitable shop

Hai,

Also a "cheap" solution is an electronic compass. They are made especially for car's. I think VDO-dayton has one, and most car-accecoiry-shops will have it.
But..... for a few $ more you have a cheap GPS-receiver, wich is far more acurate and has much more possibility's.

Maarten

Tried a cheap compass on top of my tank bag but no use - next step GPS it seems.

I got a GPS (Garmin Etrek) in Canada for 200 dollars ... which works out at about 80-90 £STG at the moment ... bargain!

There is a handlebar mount available as well.

Check out the Mountain Equipment Co-Op (I think they are online).

Cheers, LJFC.

Cheers for that:
http://www.mec.ca/Products/product_d...3Eprd_id=17629

Seems pretty neat. Let me know how you get on with it please

ta
paul

Ah .... in a high-tech world how quickly we forget the basics!

This is a good solution for any vehicle mounted compass (old army trick - good for planes, cars, armoured vehicles!):

Mount your compass wherever you decide. Then move out into an open field etc away from powerlines (don't forget to beware of underground pipes for sprinklers/gas etc) and get a mate to stand at LEAST 30m away and shoot a bearing on him. Note it down.

Next dismount your compass and walk over to your mate and shoot the back-bearing - this avoids introducing another compass with another possible compass error!

Then it's just a matter of comparing the vehicle-mounted compass bearing with the non-metal influenced back-bearing (ie subtract 180deg from back-bearing).

That will give you a quite accurate indication of the magnetic influence induced by the location of your compass on the vehicle!

Repeat as often as you change bike configuration and do it twice - engine on versus engine off!

P.S. Yes I also use a GPS, but I only switch it on AFTER I've come up with my location using map, compass and odometer - use it to check. As for vibration - I don't actually mount the compass directly on the bike - keep it in chest pocket and stop to pull it out if needed (still do the above procedure though).

I think GPS is a great and helpfull tool. But in all cases always take a good old compass with you as a backup. And also familiarise yourself with the techniques to use it!!!
A very usefull book that can help you with the basic navigation skills is:
Mountain Navigation by Peter Cliff. I think you should find it in most outdoor shops. I bought it in Scotland.
Next step: get out into the field and practice!!! Makes it a lot easier when it is for real!