Moto2 prototype

[Corvus]

Have a look at this

http://www.tonyfoale.com/Articles/Steer/STEER.htm

.............

There's another tony foale article titled "to dive or....", in which he briefly describes the two sources of dive. I found it very helpful in building up an understanding. It's an old article now and perhaps the thinking has been modified or more likely added to. The basics surely can't have changed.

[bikesnbones]

Dive under braking is desirable to a degree on a road bike, perhaps more so on a race bike.

Many years ago I was reading an interview with an engineer responsible for Yamaha's GTS1000 hub centre steering design.
He said they could, if they had wanted, engineered as much dive into the system as conventional forks,

[Corvus]

Dive under braking is desirable to a degree on a road bike, perhaps more so on a race bike.

Many years ago I was reading an interview with an engineer responsible for Yamaha's GTS1000 hub centre steering design.
He said they could, if they had wanted, engineered as much dive into the system as conventional forks,

See above referenced "to dive or" article. An explanation is in there.

The main thing which has changed since the article was written is that dive is now considered a good thing and not a bad thing. That and the fact that forks have got stiffer and lighter. Mind you, brake power has gone up too. As well as the tyres ability to provide increased stopping power.

Pity the road surface has declined somewhat.

[bikesnbones]

The main thing which has changed since the article was written is that dive is now considered a good thing and not a bad thing.

I'm curious to know why that is.
Surely when stop quickly, you need the bike to be balanced, which it won't be with the full force of the riders weight pushing down on the front end.

[Corvus]

The main thing which has changed since the article was written is that dive is now considered a good thing and not a bad thing.

I'm curious to know why that is.
Surely when stop quickly, you need the bike to be balanced, which it won't be with the full force of the riders weight pushing down on the front end.

There's an enormous can of worms wrapped up in your second sentence, I believe. Perhaps a clue maybe in trying to source any recent reading material on the subject. Most of it seems to be devoted to racing principles. That's fair enough I suppose from one point of view, as only in racing are the machines pushed to the limit of design and beyond.

But try to find something on Telelever for example. There are bits and bobs on google, but nothing authoritative really. I dunno. Maybe I'm being harsh?

[Corvus]

Herb said : "Our bikes have a degree of dive built into the geometry so you get some feedback on how hard you are braking, and squidge the front tyre into the ground on braking. "

Bikesnbones said : "Surely when stop quickly, you need the bike to be balanced, which it won't be with the full force of the riders weight pushing down on the front end."

Ok, I gotta ask this. Both the above seem to associate the diving action as the cause of tyre load. Forgive me if I've misunderstood that, I apologise if so. I have to admit that I'm struggling to see it quite the same way. I could very well be wrong and it definitely wouldn't be the first time.

I see both tyre load and fork dive as a consequence of the same phenomenon. But I can't (bring myself to) see the actual downward movement of the front end as the direct cause of tyre load. What seems to me to be a better way to think of the cause of tyre load is a line drawn between the effective c of g and the contact point to the road. Yes, movement of the suspension will contribute to c of g position.

In other words, if we could rig an experiment, on a perfectly smooth road (suspend disbelief please) using on bike with telescopic's and another with the telescopic's made rigid. Then found a (thought experiment) way of allowing the c of g on the rigid bike to move itself into the same position as the bike with springs in. Would the tyre load be the same or not?

[Herb]

It will take a brighter guy than me to understand, let alone answer your question.

If you google, there are some good articles on Telelever and other front ends. This is one I found a while back tht is pretty informative.

http://www.carbibles.com/suspension_bible_bikes.html

The Kevin Ash articles and forum posts are good too.

While Telelever on our bikes has been set up to minimise dive, the Engineers have left some dive on braking, so you get some braking feedback.

My earlier comment was misleading, I did not mean to imply that brake dive is the cause of the load transfer. I get brain fade when I think too hard about this stuff. I was trying to make a comment on the relationship between dive and rider feedback.

[bikesnbones]

Corvus.
All I'm saying is that you made a statement which I assumed was based in researched fact.

The main thing which has changed since the article was written is that dive is now considered a good thing and not a bad thing.

I appreciate you have a degree of knowledge on the subject, but I was hoping you might provide a link to illustrate the above.

[Corvus]

It will take a brighter guy than me to understand, let alone answer your question.

If you google, there are some good articles on Telelever and other front ends. This is one I found a while back tht is pretty informative.

http://www.carbibles.com/suspension_bible_bikes.html

The Kevin Ash articles and forum posts are good too.

While Telelever on our bikes has been set up to minimise dive, the Engineers have left some dive on braking, so you get some braking feedback.

My earlier comment was misleading, I did not mean to imply that brake dive is the cause of the load transfer. I get brain fade when I think too hard about this stuff. I was trying to make a comment on the relationship between dive and rider feedback.

Hi. Thanks for reply. I hope I haven't offended as that wasn't my intention at all. I guess I must be irritating sometimes. Maybe I also constructed my post badly.

The crux of what I was getting at is that I see the effective c of g as the thing we should focus on when thinking about front tyre load. Although that maybe wrong. If some knowledgable person knows otherwise then please point us in the right direction!

I have seen the linked article before and personally find some critical points very misleading. Again, it may be me who is misunderstanding things.

Re brain fade, yes, I know what you mean! The subject does seem at times to throw back conflicting information, which will get one's head spinning for sure. Still a fascinating subject though and definitely worth persisting with. Persisting is my middle name!

Herb, you have views on things, as I do, and it would be good to bounce ideas around. Although I perhaps over do things sometimes. Sorry for that!

Cheers

[Herb]

My problem is, I know just enough to get me into trouble but not out of it. My former career was in Automotive brake NVH, and as a mechanical Engineer I have a reasonable understanding of these things, but my knowledge always seems to fall just a little short.

Oh, and it takes a lot to offend me. I really enjoy these kind of posts. I think it's interesting that bikers really try to understand how their machines work. You don't see that quite so much in other fields.

[Corvus]

Corvus.
All I'm saying is that you made a statement which I assumed was based in researched fact.

The main thing which has changed since the article was written is that dive is now considered a good thing and not a bad thing.

I appreciate you have a degree of knowledge on the subject, but I was hoping you might provide a link to illustrate the above.

Hi. As above reply to herb, I hope I haven't caused offence. Not intended I assure you.

Perhaps I should have written "now SEEMS to be considered a good thing". That personal statement is based on what I perceive to be present wisdom. Certainly with regard to racing, if not quite the same degree with road machinery, especially of the non sporting type. I perceive it that way only by what I read and hear.

I clearly remember that in the late seventies/early eighties fork dive was an evil that had to be eradicated. Hence the various Japanese anti dive mechanisms. Compared to those, the Telelever system is a brilliant solution. And it is marketable, especially initially hidden behind a fairing. It is now more widely accepted, thankfully.

I'll try to find some suitable links if I can.

Cheers

[bikesnbones]

Compared to those, the Telelever system is a brilliant solution. And it is marketable, especially initially hidden behind a fairing. It is now more widely accepted, thankfully.

Interestingly, the Telelever system appeared about the same time Yamaha introduced the first mass produced hub centre steer bike.
(GTS1000)
BMW played down their clever sollution, probably mindful of the mixed reception Yamaha had received.
At the end of the day, both systems work in a very similar way, by seperating steering and suspension forces.
I'm convinced that the reason BMW succeeded is because their system looks like conventional forks and as you say, the clever engineering is largely hidden from view, so as not to upset the notoriously conservative bike buying public.
The question has to be asked though, that if it really is the last word in advanced suspension engineering, why has it been ditched for the S1000RR

[dave the german]

possibly weight?

[Corvus]

Compared to those, the Telelever system is a brilliant solution. And it is marketable, especially initially hidden behind a fairing. It is now more widely accepted, thankfully.

Interestingly, the Telelever system appeared about the same time Yamaha introduced the first mass produced hub centre steer bike.
(GTS1000)
BMW played down their clever sollution, probably mindful of the mixed reception Yamaha had received.
At the end of the day, both systems work in a very similar way, by seperating steering and suspension forces.
I'm convinced that the reason BMW succeeded is because their system looks like conventional forks and as you say, the clever engineering is largely hidden from view, so as not to upset the notoriously conservative bike buying public.
The question has to be asked though, that if it really is the last word in advanced suspension engineering, why has it been ditched for the S1000RR

I was preparing to ask exactly that same question regarding the s1000rr myself. I reckon there'll be many reasons, there usually is, but the primary one might be that, as it was intended from the start to compete and win in WSB, then they couldn't gamble on anything too risky in terms of unproven track testing at that level.

To answer your earlier request about links to substantiate what I perceive to be the recent thinking that dive is not altogether a terrible thing after all, could I refer you to the MCN article which prompted me to start this thread. If I have read it right, they say that the designer purposely build dive into his system. Whatever the true motive for him doing this, and there may be more than one, it clearly reflects that this is current thinking. Even if he himself has only done that to help "sell" his product, that still shows the need to conform to (overwhelming, by extrapolation) current thought. No?

Another interesting little snippet I've found regarding the taylormade bike is that one reason he settled on wishbone type was to allow airflow easier access to the under seat radiator.

Cheers.

[Corvus]

Just re read the MCN article and second time around the reference to diving is reading a little more tenuously!

Just greasing the push bikes' crank in readiness for some vigorous back peddling.