Measuring stuff on a bike

Pie-Roe · World Chat Champion Joined: 05 Feb 2007 Karma :

I'm trying to have some crash bars/crash cage made up on CAD for my x11. However, I'm having some difficulty working out how to measure the distance between the sets of engine mounting points. As far as I can tell, the engine is bolted in three places, just with bolts through the mounts onto brackets/engine.

The obvious way is to drop the engine and stick a long bit of wood through the holes and mark it off, but my mobility is pretty bad at the moment. My friend suggested using a perfectly curved piece of metal which then I can work out the diameter of the semicircle, but this seems pretty difficult to do. I've tried googling, and American forums are fairly helpful but not amazing.

The next step was to look at finding a frame on ebay and asking a breaker to measure it, which would be easy enough to get one to do either by some cash or saying I need a frame for a project.

The last thing I can think of is to try and mount straight pieces of metal, mechano style to the bolts and see if I can line them up and measure the distance, but that again seems problematic.

I want the bars to join up together, ideally without needing spacers in the middle, but that is a possibility. Anyone got any ideas?
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J.M. · World Chat Champion Joined: 27 Mar 2011 Karma :

Place the bike absolutely straight upwards.

Place two blocks of wood down; one each side of the bike and a known distance apart. Say 1 or 2 meters.

Measure from the frame to these blocks of wood. Add the results together and subtract them from the distance the blocks of wood are together. The resulting value should be the length of bolt required?

Never tested this mind, but it works in my head!
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Knightsy · World Chat Champion Joined: 21 Jun 2012 Karma :

Do you have the bit of wood needed for it?
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Pie-Roe · World Chat Champion Joined: 05 Feb 2007 Karma :

nope, but I can make do. I've got a fair amount of bits and bobs kicking around in my shed. Smile

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c_dug · Super Spammer Joined: 04 Sep 2007 Karma :

I don't follow, why can't you just measure point to point?
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GrantT · Scooby Slapper Joined: 03 Jun 2011 Karma :

You could make a big set of calipers with a couple of long pieces of wood (like some narrow offcuts of ply board or something) and a bolt & wingnut.

Mandatory paint diagram:

https://www.angelvw.co.uk/images/calipers.jpg

put the points of the calipers on the two places you're measuring between, tighten the wingnut, remove from bike, place on floor, measure between the two points on the calipers. Sorted.