Featherbed: Twin vs Manx, handling, weight, etc

Fast Eddie said:
Yer think… I’d never thought of that… (I’m lying of course, I’ve obsessed over it in great detail) !

I‘d love a Manx. Just can’t decide which of the kids to sell first.

Personally, I have no interest in building a 500 twin Domiracer replica. But the cheaper alternative to a Manx that I am mulling over is a 920 twin Manx…

Obviously the 920 would have quite a lot more oomph. I believe the engines would way more or less the same. I had always assumed a twin would upset the COG and spoil the fine handling of a proper Manx. But having read through some of the recent Domiracer stuff I’m not so sure.

Trouble is I am yet to meet someone who owns / has owned a good Manx who doesn’t think it’s the finest thing on two wheels…!
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It was in it's day, but those racer have crossed or are almost ready to cross the rainbow 🌈 bridge.
 
I've just remembered, why not ask Dave Degens, in Triumph 650 form he won the Barcelona 24 hours twice, and a short while back he found the old bike and brought it again.....
 
Bernhard said:
I've just remembered, why not ask Dave Degens, in Triumph 650 form he won the Barcelona 24 hours twice, and a short while back he found the old bike and brought it again.....
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I’ve ridden it Bernhard! Cracking bike.

I’ve ridden his ‘72 Barcelona bike too… and crashed it :eek:

My original question was about a big Norton twin engine vs a Manx engine.

But I’ve answered it myself now I’ve ridden a top notch Manx !
 
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acotrel said:
Historiç racing has destroyed many good motorcyçles
People try to improve on what was already good. We shiould remove the rules and.include retros. That would provide more oppotunity for development
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Fast Eddie said:
I’ve ridden it Bernhard! Cracking bike.

I’ve ridden his ‘72 Barcelona bike too… and crashed it :eek:

My original question was about a big Norton twin engine vs a Manx engine.

But I’ve answered it myself now I’ve ridden a top notch Manx !
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Glad you had a ride.
I also know that Dunstall used the Domiracer frame from Norton to insert a 750 Atlas engine prior to the Drainpipe.
It was , I belive slighty too powerful, hence his forway into building his own frame.
 
Fast Eddie said:
Yes, I realise that, but I was reading the comments about the early versions, which used Manx frames.

I can only assume the later lowboys were even better.
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Twin cylinder motors in feather bed frames are never good enough.
There is a book about Francis Beart titled,
A Single Obsession

Seeley920 said:
Don't forget, the Domiracer (Lowboy) was a different frame, specially built to accommodate twins so the engine could sit lower
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Fast Eddie said:
Yes, I realise that, but I was reading the comments about the early versions, which used Manx frames.

I can only assume the later lowboys were even better.
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Fast Eddie said:
Yes, I realise that, but I was reading the comments about the early versions, which used Manx frames.

I can only assume the later lowboys were even better.
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Fast Eddie said:
Inspired by the chat elsewhere about Rudi Thalhammer’s Domiracer, I did a bit of reading up on the Domiracers.

I confess, I was somewhat ignorant. I hadn‘t realised they were as good as they were.

In particular the commentators of the day noted the lighter overall weight of the engine, even without alloy barrels and use of exotic alloys for cases, and the lower centre of gravity. Both of these factors giving handling benefits.

I had always believed the twin could not sit low enough in the frame so has a higher COG. But, although it may sit higher, the lack of overhead cam box etc did give it an overall lower COG. Apparently.

Whilst it’s very interesting to read, has anyone ridden a Manx framed twin and a full Manx, and if so could you share your thoughts and comparisons please ?
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There is no comparison. The Manx is always better. But historiç racing does not justify the cost.
 
Fast Eddie said:
Well although I’ve never ridden a Norton twin engined fathered, I’ve ridden several Triumph / Nourish twin engined featherbeds inc one Manx rep frame. I’ve also ridden (what I like to think is) a well sorted Commando.

But having recently ridden a very well built, top spec modern Manx, I can confirm it feels totally different. Far sharper, far more precise. Basically, it felt like a thoroughbred race bike.
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When I was young if you were serious about racing you needed a Manx. I did not want my kids to starve.
 
I am now back in Benalla - for the last three weeks I have been in North Quennsland using my mobile phone to comment on this topic. Nigel, fot your 920 motor, a Seeley frame would be much better than any featherbed, In 1974 my mate and I both had feasrthebed framed Tritons. Over about 4 years I had raced against him many times.
I entered a race on a club day - he was riding my Seeley, as it was then a Seeley Laverda 750. I was on my 500ccshort stroke Triumph Triton. I blew him off easily down the back straight of Winton Raceway. As I reached the corner at the end of the straight, i applied the brake. The brake came on very hard unexpectedly whiler i was on front of him. He rode around the outside of me, popped in front of me, and grabbed a handful of disc brake. He was inside my braking distance. I barely touched the front brake again and the bike went into a massive tank- slapper and launched me at about 70 MPH. I went down thec road on the top of my head. By the time I reached a ripple in the bitumen, I was on by side. I copped a dislocated chromoclavicular joint.

I kept track of where the Seeley Laverda ended up and eventually bought it. But I could not get the Laverda motor without paying big money - even though I legally owned it. As far as handling goes, a Seeley frame makes a featherbed frame look stupid.
My mate knows what he did that day. He cannot bear to think that anybody might ever be one-up om him. Is is the only time I ever had a crash in which I really believe I could have been killed.
 
If you were building a featherbed Commando, you would need to be very careful about where you position the motor. When I fiirst got my Triton 500 the motor was a inch further back from where it finally ended up. I moved to motor as far forward as possible, and with 19 inch wheels the bike handled very well. When I fitted 18 inch wheels to get god rubber, I could still corner fast, but the bike used to exhaust me. My mates Triton 650 has about the same weight motor and 18 inch wheels and is a good ride. On both bikes 18 inch wheels gave neutral steering. But my bike with the motor one inch further forward became a dog.
The thing about the Seeley is that when I practice, I work towards the centre of corners. I brake right up into them and progressively get on the gas earlier coming out. I avoid rolling in the middlev of corners. With the Seeley, I found the change-over point was becoming earlier. So much so that I was able to get on the gas much earlier and power through the corner. I do not know if Seeley frames are supposed to do that. But it is a very fast way around.
 
ashman said:
That was you problem Al having a Triumph motor in a Featherbed frame.
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No Triton is ever as good as a Manx, But the featherbed frame is old technology. Gus Kuhn used Seeley frames. He was as quick as the factory Commandos, which had space frames and monocoque frames. THere is no way my mate could ever have ridden his Triton 650 around the outside of my Triton 500. He used to beat me towards the ends of the straights.
 
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