...so I decided to build one again, and having a certain
affectioninfatuation for Bonneville, why not make a Nimbus Bonneville Racer.
( In fact I could come up with a lot of good reasons
not to, but being an unreasonable
person I just disregard those ).
Initially I wanted to take a standard Nimbus, frame and all, and go from there,
so I started making dodgy drafts ( pretending to work )
...but it soon became apparent that it wasn't such a good idea for several reasons,
mainly that the frame is made from 'spring-steel' which is kind'of impossible to weld,
( every part of the frame is rivited (!) together, like a frekin' old bridge )
so I was VERY limited when it came to modifications, like if I wanted to alter the
angle of the front-fork.
At this time I had borrowed a clapped-out frame to fool around with
Then I took one good long hard look at the frame
...and thought to myself ; I have always had a dream of making my own motorcycle-frame,
( and filed it under "Impossible Dreams" )
and even if I have never ever so much as bend a single pipe/tube in my entire life,
and never seriously welded two pieces of steel-tubing together....if I ever should do a frame,
this is IT... a motorcycle-frame doesn't come much simpler that this one.
So back to the drawing board for some more drafts, now with the freedom to
change things around as I bloody well pleased
...and sure: there's a blower there. If it ain't blown..it sucks. Everybody knows that, ei ?!
Borrowed a few Nimbus engine-parts and stumbled into an old Danish-made fairing for a MZ bike,
and did some mock-ups to get the proportions right
and figuring out how, and where, to mount the blower
..more drawings ( still pretending to do actual work )
..decided to ditch the original tank. Didn't fit anymore after I altered the angles of the frame
and besides: it look like one of them things the old folks had under their bed
so they didn't have to go all the way to toilet at night.
Remembered that I had a tank somewhere. Came from an old Danish moped.
Lo and behold : it fitted as if this was meant to be
Heeeeey : I'm on a roll here !
Time to bribe my Mr. Computernerd colleague into making something a lot more
interesting that what he do for actual work.
In fact it didn't take any persuasion AT ALL, so a BIG thank you to Rasmus Hansen !!!
for helping me
Here's Rasmus hard at work
That went surprisingly fast. Maybe due to the fact that he has tree hands and extra joints on his fingers...dunno .
( For any co-nerds out there : I think he used a combination of Auto-Cad and Rhino .... not sure )
The drawing went up on the wall for some additional contemplation and evaluation
and after a while we did some modifications and thought on how to put the darn thing together
There was just NO way that I was going to bend those tubes myself.
As I said I'd never done it before, and I wasn't going to loose my virginity
doing it for a bike that will rush over the big white dyno at enormous speed
( yeah...right )
..so I looked up the nearest place ( didn't know where else to start ) who do CNC tube-bending.
One: it was like five minutes away..Two: they guy who picked up the phone
turned out to be an old-bike nut. Not a bad start !
He was just the nicest and most helpful guy I could ever dream of bumping into.
At this point I had read everything I could possibly find concerning the choice of
tubing for building a motorcycle-frame, including every post on that here on the forum.
I soon realized that asking about it is like asking; "What engine-oil should I use for my XXXwhatever".
NOone seamed to agree on anything, so I listened but in the end I went with what the
CNC-guy recommended:
"..32 mm / 4 mm . ( That's: 1¼ ” / 1/6 ” )
seamless cold drawn hydraulic line pipe according to DIN 2391/C...EN 10305-4...St 37.4 NBK
Carbon steel tubes for machine structural purposes.
Application: motor-car construction, pneumatic and hydraulic operating mechanisms.."
One of several things that persuaded me was the fact that that particular type
is the one that the Swedish authorities accept for home-made motorcycle frames.
( Forget about doing such a thing here in Denmark... no way ).
I does not
have to be
4 mm , but I went for that, hoping to make it strong enough
so I didn't need the bird-nest of tubing I see on other bike.
( I do understand that a thicker tube does not necessarily compensate for less tubing,
but we'll see how it works out )
It quite beefy:
OK then: I'm building a tractor...ODINs TRACTOR,
but heeey: the weight 'penalty' for going from 3mm ( 1/8 " ) to 4 mm was around 7,5 kg / 15 pound,
and who cares...not me.
So the guy had 12 meters ( 36 feet ) brought over from Sweden ( needed two 'lengths' @ 18 feet ),
CNC bend the whole darn thing for very little more than 300 US$ .. ( including the price of the tubes )
cash .. out the back-door.
There are still nice people out there.