Bimota Forum

Bud977 · Joined: 03 Mar 2013 Posts: 525 Location: Sydney

I was looking at some photos of one of the best looking Bimotas, the SB1.

I noticed the triple clamps look rather odd. It looks like the fork tubes have a negative offset in relation to the steering head.

That would sure give it some trail and make it super stable, and hard to turn, which is unlike other Bimotas.

Do you reckon that is how they are supposed to be, or should they be the other way around?

brian · Joined: 22 Aug 2011 Posts: 3769 Location: Australia

Would be good for a drag bike Lech... You're into drag bikes now aren't you Very Happy

.

I do remember a thread on here with reference to this... Maybe from Nige?

In your photo, it doesn't look like there would be much clearance between the top yolk and the tank. Maybe it is upside down?
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'99 DB4 #104, '96 SB6 #1165, '94 DB2 J #652, '99 DB4 #088, '08 VTX1800, '93 ZXR750R M1, '95 ZXR750, '95 ZXR750 Race Bike, '94 CBR400rr NC29 Race Bike, '94 CB250, '49 BSA C10 250, '61 BSA A10 650, '89 ZXR750, '91 Ducati 851

2bims · Joined: 03 Apr 2010 Posts: 7289

I'm sure others more knowledgeable than me will be along to confirm...as I've made the same mistake with early Sb3/4/KB1...thinking the top yolk was fitted the wrong way around...as those early series road bikes copied what looks like the wrong way around....where we are used to the later series it looks the same but rotated 180 degrees....
Agree though...the Sb1 is a sweet looking bike...missed out on one for sale in Italy at V cheap price needing full resto...advert came and went on the same day as it was snapped up...even a private jet wouldnt have got me there in time.... Sad

Bud977 · Joined: 03 Mar 2013 Posts: 525 Location: Sydney

I'd imagine they don't come up for sale very often, and they'd command a good price.

I think drags for the YB8 are out........for now Wink

Mike Jennings · Joined: 22 Mar 2008 Posts: 286 Location: England

Hello,

the early Bimotas used yokes with adjustable circular inserts to allow variation of the rake and trail and they should be that way round. On the other hand, no-one seems to know how the adjustments are actually made as the inserts are circular. The SB2 and KB1 used the same system. Maybe someone will explain the adjustment (please?).

Cheers, MikeJ

2bims · Joined: 03 Apr 2010 Posts: 7289

Because its a central separate "disc" inside the yoke...rather than a hole in the yoke...I think you were supposed to buy different inserts to adjust....

Mike Jennings · Joined: 22 Mar 2008 Posts: 286 Location: England

AAh....

that would explain the angle of the forks on my bike!

Cheers, MikeJ

bimotanige · Joined: 12 Jul 2010 Posts: 582 Location: yorkshire

Both my KB1 and SB3s have the same with the adjustable angle. Most of us have the taper head bearings with the taper bearing having straight rollers the same diameter along their length. I believe the correct taper roller bearings have barrel shaped taper rollers allowing them to allow the steering stem to be at a different angle in the steering head. If you then rotate the round yoke inserts the barrel shaped taper bearings allows the steering stem, hence angle to change. Without the barrel bearing it will not move or be adjustable and you then stress the yokes/ bearings. These barrel taper bearings cost a small fortune hence we use standard parallel taper bearings which " fix" the angle.
Hopefully this makes sense and is what I've worked out from various conversations.
It may be wrong but I don't think so as its a simple application of geometry 🙄🙄🙄 , ps Amen lol
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