Fork Yokes (Triple Trees)

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Very easy to check how much trail there is on a bike. Simply get a helper to hold the bike upright, and then move the steering from lock to lock.

On bikes with large amounts of trail the front end will rise and fall very noticeably, as the bars are moved, and the tyre contact patch position alters.

Less trail reduces the up and down effect, and improves handling, but means the bike is less stable, and probably not ideally suited to less experienced riders.

However the amount of trail and the caster angle, are things that are also directly related to the steering head angle, and changing one of the three things, is likely to effect the other areas to some extent.

This is the primary reason MotoGp bikes have adjustable head angles, and in most cases also adjustable caster geometry.

For anyone interested this is covered in some detail in Tony Foale's excellent book on chassis design and handling.
 
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Carbonfibre said:
Very easy to check how much trail there is on a bike. Simply get a helper to hold the bike upright, and then move the steering from lock to lock.

On bikes with large amounts of trail the front end will rise and fall very noticeably, as the bars are moved, and the tyre contact patch position alters.

Less trail reduces the up and down effect, and improves handling, but means the bike is less stable, and probably not ideally suited to less experienced riders.

However the amount of trail and the caster angle, are things that are also directly related to the steering head angle, and changing one of the three things, is likely to effect the other areas to some extent.

This is the primary reason MotoGp bikes have adjustable head angles, and in most cases also adjustable caster geometry.

For anyone interested this is covered in some detail in Tony Foale's excellent book on chassis design and handling.
That make sense Carbon, I never thought of the steering thing :)
I was never interested in chassis design until I started this Triton build, now I'm very interested, I might try and get a copy of that book.

Thanks for the info

Webby
 
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Webby — if I was in your position, I would pick up the phone and ask someone who has experience in this area, like Norman White. It would cut out a lot of the guesswork, unless you want to experiment. I think my Commando 850 has the ideal steering compromise for the road. It is quick enough to snap into corners and is wieldy round town and yet is stable on bumpy back roads. (The bike has standard forks and shock dimensions and 19 inch wheels shod with Avon Roadriders). I think this is what you should be aiming for. If you find that your experimental geometry is either too quick or too slow, all is not lost because you can change the rear ride height to compensate (i.e. shorter or longer shocks). Or fit a wider rear tyre to slow down the steering, etc.
 
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The OPs question regarding which yokes to use was accurately answered on the first page of this thread, in that yokes with less offset will result in better handling.

My main worry with any old Brit frame though, would not be which yokes to use though, but whether or not the frame was completely straight or not. The type of cheap MS tube used to make these frames tends to bend rather easily, and a bent frame is not going to handle no matter what parts are fitted to it.

Basic checks can be carried out using a digital angle gauge and a straight edge, and these will provide a very good idea of whether or not a frame is ok to use, or if its needs to go on a jig for straightening.
 
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A very valid point Carbon,
My frame was straightened and modified by Rustler Racing according to the PO. I've double checked with a couple of laser pointers, spirit levels and an angle gauge and everything appears straight.

Webby
 
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daveh said:
Webby — if I was in your position, I would pick up the phone and ask someone who has experience in this area, like Norman White. It would cut out a lot of the guesswork, unless you want to experiment. I think my Commando 850 has the ideal steering compromise for the road. It is quick enough to snap into corners and is wieldy round town and yet is stable on bumpy back roads. (The bike has standard forks and shock dimensions and 19 inch wheels shod with Avon Roadriders). I think this is what you should be aiming for. If you find that your experimental geometry is either too quick or too slow, all is not lost because you can change the rear ride height to compensate (i.e. shorter or longer shocks). Or fit a wider rear tyre to slow down the steering, etc.
Hi Dave,
I'll probably ask Dresda and see what Dave Degans has to say. Remember you cannot directly compare the set up of a Commando to a Triton, the steering head angles are different for a start. My plan is 18 inch wheels to give a larger choice of tyres, although I've yet to decide upon the width. As you say there are many other factors to play with as well, I'm in no rush to make a decision but I'll let you all know what I decide.

Thanks

Webby
 
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Webby — Yes, Dave Degens would surely advise. Sure, the Featherbed frame is different and I should have made clear that the Commando steering is merely a good standard to aim for.

Another thing you have probably thought of is your preferred riding position, since weight distribution will have an influence on handling.

Your attention to detail on steering and handling should pay dividends when you come to ride the bike. I am following this project with interest!

Dave
 
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Hi Dave,
Any comments or ideas are always welcomed!
I must admit that due to my lack of experience of anything Norton I've no real idea of what to aim for, the only comparison I have is my 71 Bonneville, which whilst it handles pretty well the steering is slower than a Norton, I'm only basing this on my measurements, the Bonnie has a Steering angle of approx. 30° with about an 1 1/2" offset. I think regardless of the set up I use on the Triton it will change direction faster than a Bonnie.
I've figured out the weight distribution, a Norton Manx has about 50/50 in stock trim, I'm hoping with the Triumph lump positioned as I have the Triton will be nearer 60/40 with the 60% on the front. This combined with the correct length rear shocks and clip ons should give a pretty good ride, I'm blessed with short legs and long arms so a traditional café racer seating position works well for me.

Webby
 
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Webby03 said:
I've figured out the weight distribution, a Norton Manx has about 50/50 in stock trim, I'm hoping with the Triumph lump positioned as I have the Triton will be nearer 60/40 with the 60% on the front. This combined with the correct length rear shocks and clip ons should give a pretty good ride,
I like your approach. It would be interesting to hear what someone with the experience of Dave Degens says. Mick Hemmings is another well-respected person who has loads of experience in this area and I'm sure he would put you on the right track.
 
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daveh said:
Webby03 said:
I've figured out the weight distribution, a Norton Manx has about 50/50 in stock trim, I'm hoping with the Triumph lump positioned as I have the Triton will be nearer 60/40 with the 60% on the front. This combined with the correct length rear shocks and clip ons should give a pretty good ride,
I like your approach. It would be interesting to hear what someone with the experience of Dave Degens says. Mick Hemmings is another well-respected person who has loads of experience in this area and I'm sure he would put you on the right track.
I copied my engine placement from Dave Degans :mrgreen:
 
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Hi Webby,
Spent the weekend reading as much as I could about yokes and understand ‘bout half of it :? . Andover Norton sell top yokes & bottom yokes for my ’71 but recommend that if you are buying both to buy the 850 ones as a pair instead. I think the PO may have swapped yokes out because of handling problems (He seems to have done every other upgrade, bless him :D ) So since my bike handles fine think I’ll stay with what I’ve got and sort steering stop problem in another way. I think another Triton man might have come up with a solution for me for stearing stops.



I did measure my offset and as you thought it was 21/4". Look forward to seeing your finnished bike.

Cheers
Keith
 
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Hi Keith,
Glad to hear you've made a decision, that would be my plan too, if it's not broken don't fix it!
I was going to suggest that type of bracket for the steering stops, whist it's a straight bolt up on a featherbed, I didn't think the Commando frame had a gusset welded between the down tubes. But I would assume a little lateral thinking could get round this, maybe attach it with a couple of 'P' clips or exhaust clamps?

Don't hold your breath to see my finished bike, I'm up to my eyeballs moving house 600 miles up the road to Belgium at the moment, at least as compensation I get a large garage & workshop :mrgreen:

All the best

Brian (Webby)
 
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Get your cheque book out Webby I’ve got the answer for you :lol: !!!

" FC Adjustable Triple-Clamps
Framecrafters triple clamp sets are cnc machined from billet aluminum. They adjust to 3 different offsets via variable center inserts. This particular model is machined to allow the Norton stanchion tubes to protrude for length adjustment. The end result is a tunable, lighter and more rigid triple-clamp system. Available for most applications."



http://www.framecrafters.net/products/

(It would be like buying a magnificent Hi-fi system; you spend the whole time listening to the Hi-fi and never hear the music :lol: !!)

Found this while I was trying to find that Featherbed steering stop bracket, do you know who sells them do you?

You’ll have your bike finished in no time. You need a big garage and workshop somewhere really quiet where nothing happens to distract you. Your going to Belgium, this is perfect :mrgreen: !!!
Cheers
Keith
 
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mcvic750 said:
...You need a big garage and workshop somewhere really quiet where nothing happens to distract you. Your going to Belgium, this is perfect :mrgreen: !!!
As if they have no beer in Belgium :roll:

Jean
 
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Jeandr said:
mcvic750 said:
...You need a big garage and workshop somewhere really quiet where nothing happens to distract you. Your going to Belgium, this is perfect :mrgreen: !!!
As if they have no beer in Belgium :roll:

Jean
That's right, no beer, no frites, no mayonnaise and no classic bike racing :mrgreen:
 
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mcvic750 said:
You’ll have your bike finished in no time. You need a big garage and workshop somewhere really quiet where nothing happens to distract you. Your going to Belgium, this is perfect :mrgreen: !!!
Cheers
Keith
Hi Keith,
Eek, those look expensive! (I didn't even bother to search for the price on the website!)
As for Belgium, I should add I'm moving back on a part time basis, I lived there before for 5 years. Despite the county's reputation for being boring I can't think of anywhere better in Europe to go out and get drunk in, the problem is most car drivers think the same every weekend!
Belgium has a very good classic bike scene, with large autojumbles and world famous racing (Chimay for example) which is much more than down here in South West France.
The downside, the roads (around Brussels at least) are sh*t and the weather is worse! As I figure I'll be spending about 50% of the month in France and the other 50% in Belgium, hopefully I'll get the best of both worlds. Also, perhaps more importantly, I'll have lots more cash to "invest" in my bikes :mrgreen:

All the best

Webby
 
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When you have cans of Tenants lager & The wee heavy none of your foreign beers impress, chips & mayo I can probably live without!! and then I watched the start of the F1 Grand Prix season today and thought of Spa-Francorchamps, at this point I would like to apologize unreservedly to the Belgian Nation for previous comments. A couple of laps there would let you know if your Tritons rake angle was good :lol:

Cheers
McVic
 
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