Paddock Stand Design - Single Side

[Mockery]

Hey guys...
I realise there are a few other topics at the moment about paddock stands, this one is slightly different and didn't merit the hijacking of anyone else's...

So I'm trying to design a paddock stand.
It was originally part of a raffle prize, to be included with a race-prepped Ducati 848 for a local charity thing - http://www.madride.org.
I was shown pictures of the Motocinelli stands and I made it up from there.

Anyway, the plan got changed/postponed or something, so I thought I'd prototype it for my bike first as a test run.
Thinking about having the spindle to rotate so the wheel can be spun, I came across this type of stand here


So, does anyone have one of these or can tell me about the bearing arrangement, and how the pin 'locks' into the rear axle? I'm thinking a rubber collar which is expanded by an over-centre lever at the end of the pin? But they have some kind of 'twisty knob thing', as it's technically known.
I would love some detailed photos if the spindle could be dismantled...

Here is a pic of the design I've got so far, please disregard the colour as I only put it there to differentiate between parts. I'm still tossing up ideas and i'm open to suggestions. I think I will be remodelling the whole thing as I switched jobs and now use Solidworks, this makes Inventor quite hard to use at home!

At the moment I have the bearings clamped in by threaded end-caps, and having the fat part on the shaft to fit 'snugly' in the spindle means that some kind of retainer will have to be bolted on at the thin end to keep it in place.
It was after mocking this up that I found that other stand with the rotating spindle, so now I'm second-guessing my idea. It seems clunky and expensive... too much material, too much machining...

Anyway, if anyone has useful input, I would welcome it!
--Mike

[Gazzahh]

Hi Mike,
I have one of those champion stands with a rotating spindle, its basicly a 20mm shaft suported by two front wheel bearings held in position by external circlips with a suitable bung to fit in the rear hub. It rotates but has no provision for locking in place, I recently aquired a stand off an MV which is too big to fit in the rear hub of the NC30, it also rotates but it is pretty crude, its solid construction but has a plastic sleeve thats held position with a circlip, my intention is to fit a couple of bearings, a hollow shaft with provision for a locking into the rear hub
Garry.

[iron chef]

Hi,
I also wanted to do this when i made my stand but i was going along the 'interference fit' road. Biggest problem with this was the seam on the inside of the tube that the bearing was going in. I ran out of time to figure this problem out but i will be interested in what people come up with cos i fancy changing my one now the rvf is back

[Le_Blur]

Could you not using an expanding wedge clamp like Rock Shox use on their 20mm 'Maxle' fork axle? It's probably a bit crude, but I guess it would stop the wheel falling off the spindle. You could have an offset cam at one end with a big quick release lever, and still have the whole thing free spinning like Gazzahh suggested.



Just an idea, like...

[Mockery]

Le_Blur, that is pretty similar to what I was thinking, but then when it's spinning you have a lever whipping about in a dangerous fashion.
I thought maybe I could have it tightened via a bolt instead. Then I need a way to hold it while tightening...
Also the shaft will have to be hollow for this and I have to work out out how much that will affect fatigue (substantial on a loaded rotating shaft).

[Cammo]

Le_Blur, that is pretty similar to what I was thinking, but then when it's spinning you have a lever whipping about in a dangerous fashion.

How fast will it be spinning?

Do you plan to start the bike up in gear on the stand?

[DAC]

So, does anyone have one of these or can tell me about the bearing arrangement, and how the pin 'locks' into the rear axle? I'm thinking a rubber collar which is expanded by an over-centre lever at the end of the pin? But they have some kind of 'twisty knob thing', as it's technically known.
I would love some detailed photos if the spindle could be dismantled...

Mike,

I have one of these units and the pin is retained in the bike stub axle by friction of the expanded rubber o-rings. Once the stand is fitted to the bike, the handwheel is tightened, which pulls the end boss (effectively a large nut) into the three o-rings, causing them to expand their outer diameter and grip on the inside of the axle. It is a remarkably secure method and definately allows the bike to be run 'in gear' on the stand. The bearings on my unit are an unusual size and too expensive when I wanted to replace them. However, after washing the grit out with paraffin and regreasing, they have been fine. I fitted a couple of homemade seals to keep the dust out. If you still want pictures, I could help out later in the week.

Regards,

Dave.

[Le_Blur]

Well, but the sounds of it, we're all talking about the same solution. DAC's stand seems to already have a fix, it's just with o-rings and a knob to tighten rather than a QR lever, but the fundamentals are the same. I think a simple solution like this is best...

[Mockery]

Hi Dave,
yeah that's pretty much what I thought it would be like. Pictures would be great if you could!
and could I ask you to take a few basic measurements such as the diameter of the shaft and the hole through it, just so I have an idea what they think is strong enough.
I'd kind of like to make the 'luxury' version, stronger and more durable, able to take the abuse of whichever numpty might win the prize. so they might want to run it on the stand for whatever reason, I'll try to design it so it can safely go fast enough and last for ages but still look relatively pleasing to the eye...

@cammo: I personally wouldn't see the need to run the bike fast on the stand, seems like a good way to mangle a finger by being tempted to lube the chain! Maybe if they were racing, it could be used with a bump-start machine?

[DAC]

Mike, I took a few pictures of my stand last night, and some dimensions.

Diameter of peg – 31mm
Diameter of sleeve – 31.75mmm
Length of peg – 57.5mm
Length of peg with boss & O-rings – 72.5mm
Length of threaded section of screw – 195mm
Bearing type 41-20-9.5





I made the sleeve from a section of corrugated bean can, to take up the excess clearance between the peg and the internal diameter of the stub axle. It prevents the bike leaning to the right when installed on the stand.

Regards,

Dave.

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