Trailer conversion for motorbikes?

[Chris152]

OK, the trailer for our dinghy is now all good after some bits have been replaced. The trailer from hitch to back is about 4.5 metres, and it's about 1.6 metres wide.

My next question is - is it reasonable to fabricate a base, to clamp (with U-bolts) to the existing trailer, to transport motorcycles? We're thinking of a rectangular frame with two or three runners for the wheels of two or three bikes to stand on, maybe an upright or two to strap to, and a simple rear frame to attach the light board. I'll do a drawing of that isn't clear.

Clearly, the trailer is too long for the bikes, but if we can avoid having to buy a separate trailer for the bikes it'd be good,

Thanks for any thoughts, C.

 

[Sideways]

What sort of bikes ?
Compared to a dinghy, there are plenty of big heavy bikes that could impose a much bigger point load on the frame and potentially bend those square section tubes if you hit a pothole.
Bikes might carry their weight higher up too, so you'll need to arrange good anchor points, good tie downs and potentially double them up. Having a strap fail and dropping a bike off the side of the trailer doesn't bear thinking about.

If we're talking a pair of 125cc trials bikes, I'm sure this must be doable

 

[Dabop]

Have you seen the 'skeleton' motorbike trailers- that kind of thing would be perfect for your bikes for two bikes (three would be an issue, because of the dinghy's rollers in the middle)

Get some C-channel wide enough to fit the bikes tyres, fit two 'sideways beams' to go from channel to channel under the channel to support them, and use U saddles to connect that to the existing center beam of the trailer towards the rear and towards the front (I would undersling them myself to lower the COG and match the height of the axle so it would then become a 'center support beam' for the channels)- the biggest issue is your two vertical hull supports on the axle itself- maybe see if you can make them easily removable, and then leave the bike runners on basically 'permanently' ie they become part of the structure of the trailer- put hull supports in for boat, take off for bikes...

(maybe a square box section just bigger on the inside than the external size of the tube on the uprights with some holes and pins to secure them in place when needed, pull the pins for removal for the bikes...)

Ideally, I would take those hull support rollers bases off, and thats where the 'channels' would sit on top of the axle, cut holes in the channels at that point to drop the supports bottom end into, and see about making up a new support bracket that both holds the channel in place permanently and supports the vertical tube of the hull supports as well, with provision for securing the supports with easy removal...

(at this point- i would go the final step and triangulate the fronts of the two ends of the beam supporting the front of the channels back to the existing center beam of the trailer towards the hitch- that would stiffen it up considerably and reduce flexing)

Although I would check the load ratings of those little tyres and of their hubs- many of them don't have much of a load rating, and motorbikes can be heavy...

If you can't quite visualise what I meant- look at the picture of that bike trailer above- yours with two bike capacity would look almost identical from the rear- but your existing trailers center 'front to back' beam that is the 'backbone' of your trailer would be in the exact same position as that center bike channel and would be its 'replacement' in that picture... the new 'front and back' support beams out to the channels would be under that existing 'backbone' like the center bike channel is in that pic, and your axle is a third 'channel support' beam in the center

 

[Dabop]

I was thinking something like this (see if it makes it clearer) existing trailer is in blue (light for axle, dark for 'backbone' beam of the trailer)
Two new support beams (basically copies of the existing axle- minus the wheels of course lol) mounted the same way and underslung the same way- shown in red
Two channels mounted on top (so basically in the same position on top as the 'backbone' beam) in orange
The two (now removable) hull support rollers basically exactly where they are now, but going through the C channels are obvious...

In yellow- 'optional extras' an extra support beam to 'make the spacing's all match, and two 'triangle brace beams' to triangulate the entire thing- which would stiffen the trailer up immeasurably!!!

Currently the axle is very poorly supported- and hitting something with a tyre could see it put under severe twisting force- say there a big pothole in the road (and for those little tyres- EVERY pothole is a big one lol) one tyre continues on straight ahead, with the entire weight of the trailer pushing at it from the 'backbone' beam- while the other tyre tries to stop 'dead in its tracks'- and all that twisting force is currently taken in a very small area by two ubolts...
(have you had issues with those center ubolts working loose over time??? I suspect so... from every little bump in the road working at them- especially as it has no suspension...)

This would make the trailer a permanent 'combo' and stiffen it up considerably into the bargain...