RRG2011 - Soft tail bobber project -- Cancelled :(

[lewist123]

So, with RRG2010 still ringing in my ears, next years project has begun.

I have sourced a better rear axle for the Chopper, so that will be fixed up and given to my son. I think I will reduce the gear ratio and tweek the brakes to increase safty. I will also fit a silence to it as it was pritty bloody loud and I don't want to anoy the locals.

So for next year.

Firstly lessons learned...

Childerns pushbike bits, unsuprisingly, can't cope with 3hp and a bumpy field, so all parts will be custom or off the shelf strong bits. BMX and hardcore downhill mountain bike bits will be used in any stock part of the drive train.

suspension is a MUST. The field was not a friendly surface to ride on. So, as per the title we are going full suspension.All parts will be donated off of a full suspension mountian bike.

Gears are also a must. In order to use the power of the mower engine (not sure what engine will be used at this stage but it will be lawn mower (I have loads)) we need at least 3 gears. One to pull away, one to get up to a good speed, and the final gear to scare the pants off.

Better brakes are needed. I want to try and blag some mountain bike disks for both front and this time rear as well.

Finally, knobbly tyres will be used this time. Smooths on a field were not working well.

So... I was on the look out for a full suspension mountain bike. Lo and behold a neighbour was throwing out a bike. Plus another neighbour has an old full suspension bike that might be up for grabs.

Here is the first bike.



Take one of these



and a set of these



blend then together with an engine (I keep looking at the 10hp briggs and smiling) and a gearbox (need ideas please on this bit) and here is what I had in mind



Does the front look right to you guys? The total length is the same as the chopper and is running the same sized wheels. Should the front have more or less rake? It looks a bit wrong.

The top frame bar will be a single large section (same as used on the chopper) the bottom bar will be two set at about 150 mm apart and tapering at the head stock and tail pivot.

I was thinking about an oil cooler using a small rad and pump I have. Plus oil cooling might be involved in some part of the intake system. I will say no more, but ideas have been growing like some kind of tumor on my brain.

I am feeling propper fired up. The skoda also took a small set closer to running today.

Lewis

[austinpowers]

Looks good to me mate.

[AtomicRooster]

That looks like the kind of thing i used to design on paint as an 8 year old. This sounds and looks epic.

[B-8-D]

gearbox wise just get a buggered small 2stroke and cut the gearbox off the crank case..
then belt or chain drive to the box....

new project looks good too...

si

[skinnylew]

oooooooooo looks like its gonna be fun liking the drawings already

[bigkris]

Lewis the sketch looks fine its probably one of them things where you looked at it so much it seems wrong now lol. I think if anything its the small tank putting the preportions out a bit. Cant wait to see this. I don't know but my mates 125 engine is off a thumpster type thing and the gearbox it semi automatic so he twisted the pedal welded a bar to it and now its sequential If you could, adapt something like that and have a suicide shifter running up the side of the frame

Somethin that looks like this:


Kris

[Deleted]

if you've got a year to source bits and build it, you may want to use some better suspension!

Those cheapy suspension bikes are truly dreadful - no damping, just springs and very poor quality.

Some modified moped, or pitbike parts would be much better suited - and they're not exactly pricey either.

Joe

[lewist123]

Thanks for the ideas so far.

Kris, perhaps you are right about the tank. I will draw a larger one later.

Joe - you have a point. I will be parts collecting for the first month. I need to sort out a rear wheel first, and work forward from that. I think a trick BMX bike wheel needs to be sourced. If anyone has one laying about please let me know.

Once I have the wheel I can build the rear frame and work forward from there.

Lewis

[griffo20022]

What about the schwinn stingray rear wheels? nice n chunky? The plan looks awesome! Be worth coming to RRG2011 just for this if all goes to plan

[BiAS]

Lewis, from experience the more rake that you put on the front forks, the harder the suspension becomes. This, on a bumpy field, makes for a very unpleasant ride. I like the shape of your paint, I reckon the proportions are pretty much spot on.
A year to accumulate all the bits? The luxury of it!

Btw your chopper was awesome (ooer!)
The size of the front sprocket creased me up ;D
Imagine how frightening it would have been with a bigger sprocket on!

eta - Glad the bug's bitten, amusing campsite transport is most definitely FTMFW

[HARDCORE]

Aug 14, 2010 20:16:24 GMT lewist123 said:

Firstly lessons learned...

Don't lend it to incompetent idiots


New plans look AWESOME! Can I have a go? ;D

[bigkris]

Aug 16, 2010 12:22:45 GMT HARDCORE said:

Aug 14, 2010 20:16:24 GMT lewist123 said:

Firstly lessons learned...

Don't lend it to incompetent idiots


New plans look AWESOME! Can I have a go? ;D

;D ;D ;D

[aij29]

Hi

How about using a frame mounted sturmey archer hub as a gearbox?

Or using a mini moto engine instead of the lawn mower engine,

Cheers
Adrian

[novocaine]

old school chopper. not as raked out as a modern jobby. leave the small tank too and a set of apes for that real old school look.

single sided swing arm will let you run a car rear wheel if your going to have a gear box.

[Deleted]

I can see why you want to stay with pushbike bits; afterall, where's the challenge in building a motorbike from motorbike bits?

If you're hankering after raked out forks, it might be worth knocking up some leading link ones if you want suspension that works (although they do have some 'interesting' handling traits).

Also, not sure if you were aware already, but you can get BMX rear wheels with left hand drive - not sure if the drive pawls in them would be quite man enough, but would enable you to freewheel if they are.

Have a look on one of the BMX forums for parts - there's always loads of bit for sale at good prices:

www.bmx-forum.co.uk/forum/

www.bmx-forum.com/forum.php

Joe

[lewist123]

Thanks for the ideas so far.

Joe - you hit the nail on the head really. It would be easier to get a 50cc stepthrough and chop that up, but that is a bit 'easy'. I like the will it work/explode excitement of this way.

Hardcore - I have a set of kids training wheels that I can sling in the car next year if you would like

Novo - I do have some skoda bits that would work for running a single rear swing arm. hmm, interesting, but I noted that last year the chap (sorry forgot who it was) who ran the trike with the single front wheel had structural issues with his single sided setup.

Thanks again for all the comments and suggestions so far.

Now, I have a questions. With the last build a few people said that running the mower engine on its side wouldn't work. It clearly did with THAT engine. The big 10hp briggs engine sat in the shed would be brillient but I fear that it really wouldn't be happy about living on its side.

Can anyone confirm or deny this for sure. I am tempted to fill it up with oil, stick it on its side and run it unloaded for half an hour. If it doesn't detonate then I might go for it.

Lewis

[HARDCORE]

Aug 16, 2010 12:49:49 GMT bigkris said:

Aug 16, 2010 12:22:45 GMT HARDCORE said:

Don't lend it to incompetent idiots


New plans look AWESOME! Can I have a go? ;D

;D ;D ;D

Ha haa! That's exactly what happened

Aug 16, 2010 21:20:32 GMT lewist123 said:

Hardcore - I have a set of kids training wheels that I can sling in the car next year if you would like

Sweet!

[Colonelk]

haha, I'm hoping to sort out some powered transport this year or even for next year. erm. or something. yeah.

A whole year this time so no excuses!

I'm looking forward to what gets cooked up by you man

[lewist123]

Thanks Mark.

Go for it. I have two spare mower engines sat in my top parts shed so if you need more/twin power then let me know. The two I have are almost identical.

Anywho, I have some more bits sorted out. I have sourced all the steel tube for the custom frame. I have some 5 mm plate in the shed that I will use for the suspension pivot plates etc.

So here is the large section roll cage for the top tube.



I will use two of the legs off this table as the bottom tube with the front bends already there. I will reduce the bend slightly from 90* to move like 80* but need to get some angles off the google sketchup plan to know for sure.



I also kept some leftover bits of kids bunk bed, the large and small sections are bound to come in handy at some point.



I also snagged a helmet from my wood-be sister in law. Gotta love the pink but it she only wanted a few quid (literally) for it so couldn't turn it down.



Don't I look the part?



I was looking for wide rear bike wheels and came across this. Not sure if I love it or hate it.



It is two rims welded together and cross laced, running two tubes and a stretched tyre.

What do you guys think? Win or fail?

Lewis

[austinpowers]

Its a win mate.