white van man 2
The 'Rocco Horror Show
- Messages
- 134
you might want to have a look at the VRS dolly things as used by the AA and RAC for inspiration. obviously for a boke it wouldn't need to be quite so solidly built
- Thread starter mich
- Start date
Not to detract from your thread mich and it looks useful, and I get your kit is splash lubed. But Im just glad this discussion came up! Ive seen the dolly's about and on ebay and I too have been toying with making one. But, almost everything I thought of towing like this falls into the above category! Gs's, a gpz11 and others...
Discussions in public are good for everyone's benefit.
Absolutely agree! I know that sometimes people may tell me stuff I don't want to hear, but its better to know all the pro's and con's before embarking on one of these projects, and most importantly, wreck a bike!! So, it remains to be seen how it actually tows. Shame I won't have time tonight to test it, but I will tomorrow.
Right, Report! 
to sum it all up, it was an interesting experience...
The whole thing works and is stable, but there is a number of issues that I need to address/have already addressed:
1 - The dolly sits too high. I need to lower it as much as possible without it constantly scraping on the floor when towing (see last photo). I mounted it that high cause I was afraid the rear of the car would squat with the weight of the bike... I presume I can safely lower it a bit more...
2 - Reversing with a bike is EXTREMELY sensitive. You can only make very small steering inputs and don't expect to reverse at 30mph!! This needs to be taken VERY slowly I found... Far worse than reversing with a trailer
3 - The setup works better for longer wheel based bikes such as Harley's. A short wheel base bike sits too high and the angle on the steering head is too steep, so it becomes more sensitive and wants to tip over to the sides more when cornering.
4 - Did I mentioned cornering? Difficult thing to do because the bike wants to tip to the side and then the forks tip backwards (see photos). Its OK for normal corners and roundabouts but in tighter bends the bike dangerously tips to the side.
This is however resolved by securing the top of the steering head so that it cannot pivot too much backwards (see photo) Also, lowering the dolly and towing a bike with longer wheel base will make this easier.
Apart from that its good!
I'm planning to make a video over the weekend, once I've modified the dolly, so that you guys can see how it actually tows around corners and stuff.
==============
First test run. The bike is sitting WAY too high. And because it hasn't got any weight due to lack of engine and stuff, its not squatting the rear suspension of the car as much as I calculated...
Thats what happens when you take a tight bend, like going into a forecourt or parking lot. The bike tips to the side and the forks tip backward.
This can however be resolved by securing the steering stem, so that the forks can only go backwards so much. This still allows the bike to steer, but it doesn't oversteer.
And, as you can see here, it now doesn't tip so dangerously anymore.
That's how high it currently is off the ground. 25cm or 10" in old money
That's how it currently looks...
And this is the bracket I want to weld in to lower the whole thing. I could even drill another set of holes here in the middle, so that I can have 3 'levels' I can mount the thing at. For heavier or lighter bikes...
Video to follow on the weekend!!
to sum it all up, it was an interesting experience...
The whole thing works and is stable, but there is a number of issues that I need to address/have already addressed:
1 - The dolly sits too high. I need to lower it as much as possible without it constantly scraping on the floor when towing (see last photo). I mounted it that high cause I was afraid the rear of the car would squat with the weight of the bike... I presume I can safely lower it a bit more...
2 - Reversing with a bike is EXTREMELY sensitive. You can only make very small steering inputs and don't expect to reverse at 30mph!! This needs to be taken VERY slowly I found... Far worse than reversing with a trailer
3 - The setup works better for longer wheel based bikes such as Harley's. A short wheel base bike sits too high and the angle on the steering head is too steep, so it becomes more sensitive and wants to tip over to the sides more when cornering.
4 - Did I mentioned cornering?
Difficult thing to do because the bike wants to tip to the side and then the forks tip backwards (see photos). Its OK for normal corners and roundabouts but in tighter bends the bike dangerously tips to the side. This is however resolved by securing the top of the steering head so that it cannot pivot too much backwards (see photo) Also, lowering the dolly and towing a bike with longer wheel base will make this easier.
Apart from that its good!
I'm planning to make a video over the weekend, once I've modified the dolly, so that you guys can see how it actually tows around corners and stuff. ==============
First test run. The bike is sitting WAY too high. And because it hasn't got any weight due to lack of engine and stuff, its not squatting the rear suspension of the car as much as I calculated...
Thats what happens when you take a tight bend, like going into a forecourt or parking lot. The bike tips to the side and the forks tip backward.
This can however be resolved by securing the steering stem, so that the forks can only go backwards so much. This still allows the bike to steer, but it doesn't oversteer.
And, as you can see here, it now doesn't tip so dangerously anymore.
That's how high it currently is off the ground. 25cm or 10" in old money
That's how it currently looks...
And this is the bracket I want to weld in to lower the whole thing. I could even drill another set of holes here in the middle, so that I can have 3 'levels' I can mount the thing at. For heavier or lighter bikes...
Video to follow on the weekend!!
For #1 you could rejig that so the actual bike wheel is the lowest part of it, rather than having braces running downwards towards the tow head. That way you could get the bike much much lower relatively and completely eliminate the geometry issues causing it to tip in corners without compromising ground clearance of the rig and risk it bottoming it out.
It might be easier to make a mk2 with this in mind though. You probably can get the wheel lower in relation to the bracket without major re-engineering though...
If you look at this one on ebay , the design has achieved the above, probably he's on his mk2 or mk3 version too
http://cgi.ebay.co.uk/TRIKE-MOTORCY...59?pt=UK_Motorcycle_Parts&hash=item43a14299cf
Now, if you could get your wheel to sit as low as that one, but still keep the over centre bike wheel catch in your design, that would be a good evolution of design...
You may be happy with it how it is, in which case these thoughts are for them to pick up the baton instead
Thought about towing backwards to avoid gearbox issues, but that creates issues with having to lock the steering solid and straight somehow. Could drop the drive chain off the sprockets, but that would mean I got covered in filth and old chain lube every time it got unloaded... Pity as one tucked in a locker on the back of the motorhome would remove the need to drag a trailer round and worry about it getting nicked when camping etc, and would still mean I could share driving duties on a long run but have my bike on hand for some fun...
It might be easier to make a mk2 with this in mind though
. You probably can get the wheel lower in relation to the bracket without major re-engineering though...If you look at this one on ebay , the design has achieved the above, probably he's on his mk2 or mk3 version too
http://cgi.ebay.co.uk/TRIKE-MOTORCY...59?pt=UK_Motorcycle_Parts&hash=item43a14299cf
Now, if you could get your wheel to sit as low as that one, but still keep the over centre bike wheel catch in your design, that would be a good evolution of design...
You may be happy with it how it is, in which case these thoughts are for them to pick up the baton instead
Thought about towing backwards to avoid gearbox issues, but that creates issues with having to lock the steering solid and straight somehow. Could drop the drive chain off the sprockets, but that would mean I got covered in filth and old chain lube every time it got unloaded... Pity as one tucked in a locker on the back of the motorhome would remove the need to drag a trailer round and worry about it getting nicked when camping etc, and would still mean I could share driving duties on a long run but have my bike on hand for some fun...
Yep, considering all the options a small folding trailer always wins hands down. And I'm not about to dispute that. However, given what this thing cost me to build, I can't beat it for value!
I've now managed to amend the design to lower the whole setup by 12cms or 4.7". That's as low as I could go and its probably not safer to go any lower or the thing will drag its knuckles on the asphalt. The bike now sits a LOT lower, which is welcome news for cornering. Still gotta weld in a small brace to strengthen the setup, but then it'll be done
This is the bracket I still have to add. Then another lick of paint and its done!
I've now managed to amend the design to lower the whole setup by 12cms or 4.7". That's as low as I could go and its probably not safer to go any lower or the thing will drag its knuckles on the asphalt. The bike now sits a LOT lower, which is welcome news for cornering. Still gotta weld in a small brace to strengthen the setup, but then it'll be done
This is the bracket I still have to add. Then another lick of paint and its done!
pedrobedro
Man at Matalan
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- 13,090
- Location
- CX near Chesterfield
You could buy a 4" drop plate for £4 or £5 or make one if you have steel thick enough, you just need another two bolts.
the snooper
getting older by the day
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- 21,086
- Location
- Hull UK
4.7 inch from the ground hope you dont come across any speed bumps
Yep, it's here! And its a brilliant design I think. Very minimalistic, light and low, yet high off the ground. Better than mine I have to say... mine weighs a ton!! 
http://www.instructables.com/id/Motorbike-towing-cradle/step2/The-story-continues/
http://www.instructables.com/id/Motorbike-towing-cradle/step2/The-story-continues/
white van man 2
The 'Rocco Horror Show
- Messages
- 134
there's a bit of pointless EU bureaucracy that gives a reccommended speed ramp height of 100mm (4") so should be fine
Yep, it's here! And its a brilliant design I think. Very minimalistic, light and low, yet high off the ground. Better than mine I have to say... mine weighs a ton!!
http://www.instructables.com/id/Motorbike-towing-cradle/step2/The-story-continues/
yea gods, is that made of rebar??? I'd rather have yours with a couple of geometry changes...
tow dolly
MIch you have done a grand job there .
-A bit on the elaborate side for me
As an old man who doesn;t want to give up biking entirely I am downsizing to a scooter but they are mostly all in england so I have your problem.
I was wondering if you could give me the thicknesses of the various parts the tube the bars and spats Please.
Personnaly I would never tow a bike without removing the chain and I am worried in the case of a scooter which as you know has a rubber band transmission??? should I disconnect it .Can be a sod to remove on some models
MIch you have done a grand job there .
-A bit on the elaborate side for me
As an old man who doesn;t want to give up biking entirely I am downsizing to a scooter but they are mostly all in england so I have your problem.
I was wondering if you could give me the thicknesses of the various parts the tube the bars and spats Please.
Personnaly I would never tow a bike without removing the chain and I am worried in the case of a scooter which as you know has a rubber band transmission??? should I disconnect it .Can be a sod to remove on some models
Pete.
Member
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- 14,974
- Location
- Kent, UK
Gearbox/tyre/chain are a complete non-issue for towing because quite simply there's barely any load on any of it, only enough to turn the layshaft and a few gears. In any case, involute gears don't rub (much) - the faces roll against each other.
My lathe runs open gears for hours on end with no lube (and that's with a load).
You're right about the wheel height it needs to be as low s possible without fouling humps. Figure on the bottom of the tyre being level with the lowest part of the hitch then it should just clear everything hopefully.
My lathe runs open gears for hours on end with no lube (and that's with a load).
You're right about the wheel height it needs to be as low s possible without fouling humps. Figure on the bottom of the tyre being level with the lowest part of the hitch then it should just clear everything hopefully.
How about taking the front wheel out and securing the bike to the carrier via the front wheel spindle? That way you're more securely locked in and can drop the bike by the front wheel radius? You could go lower then without worrying about speed bumps etc. too.
Ok, pulling the front wheel adds a bit of hassle but shouldn't take too long?
Ok, pulling the front wheel adds a bit of hassle but shouldn't take too long?
