A decent handlebar mounted compass?

[The Mechanic]

How did mariners navigate aboard steel-hulled ships before practical gyrocompasses were invented (ca 1908)?
But apparently magnetic compasses can be used in cars (eg attached to the windscreen), aboard steel-hulled ships, metal aeroplanes, etc.

Compasses have to be adjusted, see here http://www.compassadjustment.com/#3

"The aim of the compass adjuster is to nullify the effect of the unwanted magnetic fields by placing compensating magnets and soft iron correctors adjacent to the compass. These create equal but opposing magnetic fields, thus eliminating the deviating fields around the compass, enabling it to align correctly. Each axis, vertical, longitudinal and athwartships is treated seperately."

The link above explains it pretty well. Kelvin's Balls (one either side of the compass) and the Flinders Bar (a tube holding lumps of soft iron in front of the binnacle) are both parts of the correction mechanism as are rod magnets that fit into the compass binnacle as required during the adjustment process. The role of a Compass Adjuster is a specialist one but any Master Mariner worth his salt should be able to have a fair stab at it in an emergency. It is part of the training.

FYI, after adjusting the compass, the Adjuster will produce a table of Deviations which gives the amount and direction of the deviation for all points of the compass (usually in degrees these days). This needs to be combined with the Magnetic Variation, to get the true reading from a compass. Magnetic variation is due to the fact that the magnetic poles are not in the same place as the geographical poles so the compass actually points to the magnetic north pole. Variation is usually indicated on nautical charts and other publications.

[Malaconotus]

Kelvin's Balls (one either side of the compass) and the Flinders Bar (a tube holding lumps of soft iron in front of the binnacle) are both parts of the correction mechanism as are rod magnets that fit into the compass binnacle as required during the adjustment process. The role of a Compass Adjuster is a specialist one but any Master Mariner worth his salt should be able to have a fair stab at it in an emergency. It is part of the training.

FYI, after adjusting the compass, the Adjuster will produce a table of Deviations which gives the amount and direction of the deviation for all points of the compass (usually in degrees these days). This needs to be combined with the Magnetic Variation, to get the true reading from a compass. Magnetic variation is due to the fact that the magnetic poles are not in the same place as the geographical poles so the compass actually points to the magnetic north pole. Variation is usually indicated on nautical charts and other publications.

This all sounds a little excessive for a handlebar mounted compass. Perhaps the OP should consider a pocket compass instead.

[simonhill]

As above, I use a pocket compass and my suggestion is try one first. You can get a cheapie with cover that works OK for about a quid or two. Not much bigger than a £2 coin. Try and see.

I also have a very cheap plastic (OK iron needle) Chinese compass which was a kids wristband toy. I bought it in China when my compass broke. It cost about 10p and I still keep it in my trousers/shorts for walking in town use.

[iviehoff]

How did mariners navigate aboard steel-hulled ships before practical gyrocompasses were invented (ca 1908)?

Compasses have to be adjusted, see here http://www.compassadjustment.com/#3

"The aim of the compass adjuster is to nullify the effect of the unwanted magnetic fields by placing compensating magnets and soft iron correctors adjacent to the compass. These create equal but opposing magnetic fields, thus eliminating the deviating fields around the compass, enabling it to align correctly. Each axis, vertical, longitudinal and athwartships is treated seperately."

Fascinating, thank you.

[simonineaston]

I've learnt to use the sun, (although thick grey clouds get in the way...) and you need to have a look at a suitable website before setting off on your tour so you have a good idea where and when the old currant bun is!
Here's today's for London...
http://www.locationworks.com/sunrise/ch ... 130522.pdf
When the sun is shining it's quite easy to see roughly which direction you are heading in from your shadow - Great Fun!!
Doesn't work at night though, but then, neither do I

[The Mechanic]

At night you can use the pole star aka Polaris. Clouds are still a bit of an issue though.

[cyclist]

I tried an expensive compass that is mounted on the stem cap (top cap) on an Aluminium alloy bicycle. It did not work out at all. The compass was a ball. The compass was stuck in one position and did not show the direction at all, after a few trials, I contacted the company, they did not have an answer, they asked my to return it back. When I tried to pop it out, it fell and broke. That was the last time I tried.

[Mtb tourer]

Buy a cheap Garmin head unit, can have compass or a header above the map giving direction travelling if you can't see the little north icon on the map page.

[mdskids]

If you happen to use a map case on top of a handlebar bag (e.g. ortlieb) you can just put a normal hiking compass in that, on top of your map. Or (this is what I do) remove the compass part (the capsule) from the baseplate and just slip this into your map case, since all you normally need is to know which direction is North.

[POIDH]

...

[simonhill]

Not all smartphones have an inbuilt compass. (check your specs). The ones that do can use the apps. The others use GPS to get compass directions which isn't actually a compass and can suffer usual GPS problems

I think???

[Carlton green]

From my experience so far there is no such thing as a decent handlebar mounted compass, well not one that works by traditional magnetic forces. Traditional compasses have a magnetic bar in them that aligns north to south along its length, it is attracted to the magnetic poles of the earth. Magnets are also attracted to steel and bikes are often made of steel, hence there’s a tendency for compasses to give false readings when near to steel items like a steel bike frame and steel handlebars.

Whilst I rarely need them I almost always have a button compass or two with me on my bike (stored in a saddlebag, etc.). They aren’t subject to unexpectedly flat batteries, they take up virtually no space and they only cost pennies; when held clear of anything with iron in it they give a useful indication of where North is - and likewise South, East and West.

The thread is old, the early responses by Simon Hill and The Mechanic are worth reading.

[Al Wright]

["iviehoff wrote:
How did mariners navigate aboard steel-hulled ships before practical gyrocompasses were invented (ca 1908)? "
---------------------
In iron clad ships, not very well it seems, the Tayleur is an example; https://en.wikipedia.org/wiki/RMS_Tayleur

"Tayleur left Liverpool on 19 January 1854, on her maiden voyage, for Melbourne, Australia. Her compasses did not work properly because of the iron hull. The crew believed that they were sailing south through the Irish Sea, but were actually travelling west towards Ireland. "
She ran aground on Lambay island a few miles from Dublin.

[Cowsham]

If your bike frame is steel then a compass on the handlebars will not give you an accurate reading. There will be a variable amount and direction of deviation caused by the frame's own magnetic field.

^^^ This ^^^

I have this compass bell on my LHT.... http://www.winstanleysbikes.co.uk/produ ... tAodXDwA9w Doesn't work.

Tried one too -- same conclusion

[Mike Sales]

So,if you want a compass on your bars to be accurate, you should fit Flinder's Bars, Kelvin's Balls and then swing the compass to compile a deviation table. Or you could just use an OS map. I don't comment on electronic devices beyond my ken.
Try navigating in thick cloud in the Skye Cuillin, where the compass is untrustworthy and the terrain intricate.