View Full Version : Raked triple trees?
This is quite a technical question and I'm just at the beginning of finding out about it myself.
How many modern racebikes or or puresports roadbikes come out with raked triple trees. Is there any real advantage in this increased complexity from a manufacturing point of view?
Thanks in advance.
Also would I expect to see much difference between the rake and trail figures for a Moto3 vs a MotoGP bike.
What am I missing? What do you mean "raked triple trees"?
nodrog
28th May 2013, 13:28
http://www.youtube.com/watch?v=TZ3IXY4PYd4
Maido
28th May 2013, 13:31
is that flash talk for adjustable steering head angle? If yes, then just about every race bike at a world level has them (and some in domestic competitions too, naughty naughty)
is that flash talk for adjustable steering head angle? If yes, then just about every race bike at a world level has them (and some in domestic competitions too, naughty naughty)Standard equipment on some Ducati models.
No not at all like Ducatis two way turn it 180 degree thing.
Its when the forks are not at the same angle as the steering axis. This alters the trail to rake numbers. So you could get more trail with less rake.
Kinda like offset works but provides more leverage at the grips/handlebars
Mental Trousers
28th May 2013, 13:54
is that flash talk for adjustable steering head angle? If yes, then just about every race bike at a world level has them (and some in domestic competitions too, naughty naughty)
I think Gary might be talking about the offset of the top triple clamp relative to the bottom triple clamp being different. It changes the angle of the forks so they're different to the angle of the steering head.
At least that's how I read it.
I think Gary might be talking about the offset of the top triple clamp relative to the bottom triple clamp being different. It changes the angle of the forks so they're different to the angle of the steering head.
At least that's how I read it.
Yes you got it. Great easy way to explain it.
Oh right. Never heard of it before.
Makes bearing tolerances and tension UUUUUBER important.
Grumph
28th May 2013, 14:38
There's no advantage to non parallel triples. Rake angle is still the steering head angle.
It is one way to compensate for the wrong trail however but it's still a lot better to either make clamps with a different offset or as has been mentioned use adjustable head races.
codgyoleracer
28th May 2013, 14:42
Take a look at a harley, they do it as standard. Head angle different to fork angle.
Tony Foales book explains it all very well
There's no advantage to non parallel triples. Rake angle is still the steering head angle.
It is one way to compensate for the wrong trail however but it's still a lot better to either make clamps with a different offset or as has been mentioned use adjustable head races.
I think it would add stability, because the front of the bike wouldn't rise and fall as much when turning the bars...Maybe. I'd prolly need to draw it and think for too long before I knew one way or the other.
Take a look at a harley, they do it as standard. Head angle different to fork angle.
Tony Foales book explains it all very well
Yeah but don't Harley do it backwards? They are decreasing the trail.
Desirable to have less steering head rake and increase the trail.
And I think is not to do with when the bikes upright but when its at full lean.
I think it would add stability, because the front of the bike wouldn't rise and fall as much when turning the bars...Maybe. I'd prolly need to draw it and think for too long before I knew one way or the other.
Something like that I reacon. Why else would they go to all that trouble. Apparently you can get adjustable versions of this too.
nodrog
28th May 2013, 15:01
.... Apparently you can get adjustable versions of this too.
yep
http://www.podiumracingonline.com/chassis-suspension/triple-clamps/adjustable-offset-triple-clamps-kit-showa/prod_125.html
Something like that I reacon. Why else would they go to all that trouble. Apparently you can get adjustable versions of this too.The offset difference in the triple clamps themselves is fixed. It'd be pretty bloody hard to make that, and the angle of the fork holes adjustable.
yep
http://www.podiumracingonline.com/chassis-suspension/triple-clamps/adjustable-offset-triple-clamps-kit-showa/prod_125.html...Or not...
Yeah Glen had a set of those on the SV right Glen?
bogan
28th May 2013, 15:09
A guy made an adjustable rake bearing set for a hawk a while ago, looked fooking expensive but mechanically sound from memory, can possibly dig it out if it would be of interest. Basically it just offset the stem angle from the headstock; which sounds like what a raked triple tree would do anyway?
...Or not...
Don't think that is adjustable rake...
yep
http://www.podiumracingonline.com/chassis-suspension/triple-clamps/adjustable-offset-triple-clamps-kit-showa/prod_125.html
These only allow for parallel offset.
Mental Trousers
28th May 2013, 16:04
This looks useful
http://www.eurocomponentsusa.com/_files/pdf/E0516.mounting_instructions.pdf
A guy made an adjustable rake bearing set for a hawk a while ago, looked fooking expensive but mechanically sound from memory, can possibly dig it out if it would be of interest. Basically it just offset the stem angle from the headstock; which sounds like what a raked triple tree would do anyway?
One thing a raked triple tree may achieve is less dive under braking and less stiction when cornering!
This looks useful
http://www.eurocomponentsusa.com/_files/pdf/E0516.mounting_instructions.pdfMakes it clear as to why too. Puts the contact patch on the right side of things.
This looks useful
http://www.eurocomponentsusa.com/_files/pdf/E0516.mounting_instructions.pdf
Now thats the adjustable ones. Picture will explain what many words wont.
Pretty crappy and look like for old bikes.Just saw bottom of page Choppers!
Roadracing the forks are made steeper than the steering head rake.
Will have to do a drawing maybe
lostinflyz
28th May 2013, 17:20
as far as i am aware almost no modern racing bikes use raked trees, except when making something unique.
i had a set (iceparts) on my SXV when i first started racing it. They worked remarkably well.
Most adjustable triples are for offset (trail only) as this is the only figure that really matters, that you can adjust within practical limits using various inserts. The raked triples merely machine the steering stem in the inserts to be at an angle to the pockets in the triples that the inserts fit.
A change in the rake angle using raked triples is a massive change as the rake angle on the bike remains the same but the forks sit at an offset to this, making major changes possible to trail without too much modification. One big problem that in the dynamic case of a motorcycle steering the trail can vary quite significantly making raked triples very difficult to work with.
jellywrestler
28th May 2013, 17:20
Standard equipment on some Ducati models.
Adjustable ones standard on my 1980 Bimota SB3, they're old hat
Adjustable ones standard on my 1980 Bimota SB3, they're old hatThat's fuckin cool!
nodrog
28th May 2013, 17:34
These only allow for parallel offset.
not if you use different spacers top and bottom
not if you use different spacers top and bottomThey'd need to be angled as well as offset.
nodrog
28th May 2013, 17:44
They'd need to be angled as well as offset.
not if you are a rough cunt.
not if you are a rough cunt.I think we both know that I am. But I expect the clamps would snap if you tried to pinch the fork with any note worthy degree of angle.
nodrog
28th May 2013, 18:54
I think we both know that I am. But I expect the clamps would snap if you tried to pinch the fork with any note worthy degree of angle.
Dont the spacers go on the stem?
Kickaha
28th May 2013, 18:59
however but it's still a lot better to either make clamps with a different offset or as has been mentioned use adjustable head races.
Knock me some up for the Bucket then
Dont the spacers go on the stem?Didn't look at the picture that well. If that's the case, that system only adjusts the steering angle. Not what these dudes are on about.
Mental Trousers
28th May 2013, 19:04
Yeah they're for choppers and Harleys, but they illustrate what's going on.
On a race bike often the back end will be jacked up way above the standard setting, thereby reducing the trail on the front wheel. So adjusting the rake to slightly steeper than the steering head angle gives you more trail, offsetting that lost from jacking the arse up.
Fully adjustable triple clamps are something I've lusted over since I started racing.
Now thats the adjustable ones. Picture will explain what many words wont.
Pretty crappy and look like for old bikes.Just saw bottom of page Choppers!
Roadracing the forks are made steeper than the steering head rake.
Will have to do a drawing maybe
nodrog
28th May 2013, 19:06
Didn't look at the picture that well. If that's the case, that system only adjusts the steering angle. Not what these dudes are on about.
If the top of the stem stayed in the same place and the bottom of it moved forward, is that not raked out?
Fucked if I know whats happening.
bogan
28th May 2013, 19:19
If the top of the stem stayed in the same place and the bottom of it moved forward, is that not raked out?
Fucked if I know whats happening.
Yeh it would be, but I'm pretty sure Robert Taylor's intuition would have him turn up at your garage and smack you upside the head if you tried tightening it up with mismatched offset plates :bleh:
Mental Trousers
28th May 2013, 19:25
That's different. Adjusting the top and bottom of the stem means the forks are still parallel. Whereas different offsets on the triple clamps the forks are at a different angle to the steering head.
Changing the steering head angle changes the wheel base of the bike. Changing the offset of the triples allows you to keep the same wheel base if done correctly.
If the top of the stem stayed in the same place and the bottom of it moved forward, is that not raked out?
Fucked if I know whats happening.
If the top of the stem stayed in the same place and the bottom of it moved forward, is that not raked out?
Fucked if I know whats happening.Trying to adjust the fork angle, independant of the head stock angle. So as to change the trail to a different degree, relative to steering postion.
I think. I'm not that bright.
bogan
28th May 2013, 19:42
Trying to adjust the fork angle, independant of the head stock angle. So as to change the trail to a different degree, relative to steering postion.
I think. I'm not that bright.
It's more to do with suspension action I think. Cos with a raked tree, it's still pivoting around the headstock angle, same as with a parralel tree with modified offest. But then as the suspension moves, it's not parrallel to the steering angle, so the effective fork offset changes based on suspension position.
I think. I'm not a racer.
It's more to do with suspension action I think. Cos with a raked tree, it's still pivoting around the headstock angle, same as with a parralel tree with modified offest. But then as the suspension moves, it's not parrallel to the steering angle, so the effective fork offset changes based on suspension position.
I think. I'm not a racer.I don't see the gain, but that doesn't mean it's not there.
bogan
28th May 2013, 20:03
I don't see the gain, but that doesn't mean it's not there.
Neither. Front swingarm sounds like a way better solution...
Neither. Front swingarm sounds like a way better solution...Never ridden anything with one, but I'm told there is next to no feel.
bogan
28th May 2013, 20:09
Never ridden anything with one, but I'm told there is next to no feel.
Bloody useless riders, always nitpicking at sound engineering solutions :bleh:
Ocean1
28th May 2013, 20:34
That's different. Adjusting the top and bottom of the stem means the forks are still parallel. Whereas different offsets on the triple clamps the forks are at a different angle to the steering head.
Changing the steering head angle changes the wheel base of the bike. Changing the offset of the triples allows you to keep the same wheel base if done correctly.
Buell changed the XB12X for the last model. They'd always had piss poor steering lock, so they made new clamps with the forks an inch further forward, to get more clearance from that big fuckoff headstock. They also moved the axle back 1" in the fork endcap. Same rake, same trail, more steering angle.
Split spherical clamp inserts have been around for engineering applications for ages, they'd work just fine with an eccentric sleeve in the fork clamps to change fork angle.
Edit: I'm not convinced that the offset and head angle required to get the correct trail just happens to be the optimum angle for the forks to work at. It's certainly easier to manufacture bikes that way but I wonder how close the resulting fork angle is to the angle that results in the least side, (fwd/aft) load, IE: pointing directly at the compression forces.
AllanB
28th May 2013, 20:58
It was an old chopper trick for use with extended forks - a raked offset set of trees allowed one to extend the fork tubes and still had a good 'look' without altering the frames stearing head. Without them you got that sitting up dog look in the front end.
A quick Google looks like they are mainly being used in the States for the same reason ..........
http://pipedreamz.biz/chopperfaq.html
lostinflyz
28th May 2013, 21:08
It's more to do with suspension action I think. Cos with a raked tree, it's still pivoting around the headstock angle, same as with a parralel tree with modified offest. But then as the suspension moves, it's not parrallel to the steering angle, so the effective fork offset changes based on suspension position.
I think. I'm not a racer.
283369
youll see the insert is machined at an angle to the actual triple clamp, so as you say about the headstock angle remains the same but the wheel/fork assembly itself is moved closer to the bike, on a smaller angle. This effectively increases trail noticeably (for a sportbike/motard/anything thats not a chopper), as well as shortens the wheel base and modifies the weight distribution on the bike.....
Yes it very much changes on bike dynamics, but so does a normal bike, just not to the same degree.
lostinflyz
28th May 2013, 21:12
It was an old chopper trick for use with extended forks - a raked offset set of trees allowed one to extend the fork tubes and still had a good 'look' without altering the frames stearing head. Without them you got that sitting up dog look in the front end.
A quick Google looks like they are mainly being used in the States for the same reason ..........
http://pipedreamz.biz/chopperfaq.html
that product is interesting, it actually is negating the stock steering head and replacing it with offset bearings mounted through the now redundant steering head.
jellywrestler
28th May 2013, 21:25
Never ridden anything with one, but I'm told there is next to no feel.
stev lindsell got ninth in the 1994 senior TT on one, (and didn't die) and he was no miracle rider
stev lindsell got ninth in the 1994 senior TT on one, (and didn't die) and he was no miracle rider
I think the handling and traction is supposed to be sublime, my understanding was though that one has no idea how far from the limit they are because if said lack of feel. The steering doesn't get any heavier or lighter with load and grip levels.
Grumph
29th May 2013, 07:22
stev lindsell got ninth in the 1994 senior TT on one, (and didn't die) and he was no miracle rider
Oh, I don't know, anyone who can get something Enfield powered around the IOM at just under the ton ain't too bad at miracles....
I knocked up a pic from the "chopper pdf" so everyone gets the idea of whats meant.
Mental Trousers
29th May 2013, 09:14
I knocked up a pic from the "chopper pdf" so everyone gets the idea of whats meant.
Dodgy cut/paste/skew/try-and-blank-out-bits but it illustrates the point wonderfully :)
codgyoleracer
29th May 2013, 09:50
283401
Heres some raked triple trees.......
283401
Heres some raked triple trees.......
I think I can see the trail too.
RS2000
31st May 2013, 00:00
stev lindsell got ninth in the 1994 senior TT on one, (and didn't die) and he was no miracle rider
No miracle, mr Jelly, but an absolutely fast and brilliant rider, maybe a bit of the subject, but he was one of the fastest roadracers in his day, he was 8th by my recollection, not sure if that was F1 or Senior race tho? with the likes of Dunlop. Hislop and Mccallen in front of him he was no slouch, I would consider him a miracle rider to get in the top ten that year
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