Manky Monkey Motors

I have just Spoken to Draken1, and he offered me some excellent friendly advice on building my first trike.  He has drawn my attention to the importance of trail.  Recommended trail for good handling seems to be in the region of 2.5 to 4".  On my intended set up I have worked out the the trail I would get (using a rake of 45 deg, offset of 1.25" (Suzuki RM yoke), and a 21" rim) would be about 12" !!!!!!  So this means good high speed stability but difficult handling at low speed characterised by heavy steering.  My question is do any of you guys take the trail seriously?  If so what is your trail?  I really like the look of Critches trike but by printing a picture off and drawing a few lines and making one or two assumptions It would seem as though he has a similar trail (11").  I have done this for a few trike pictures on here and they all appear to come out way more than the recommended amount.  I'm now thinking about designing custom yokes (unless anyone has some for sale ;D) to increase offset, run a 19" rim and lessen rake to around 40 degs.  Even this will only take me to about 7.6" (2.5" offset). 

What do you guys do about this  ??? - put up with heavy low speed handling and slap on some dirty big bars?  Can anyone recommend a good fork/yoke combination without the need to make custom yokes, afterall its my first build and I fully expect to make other mistakes even if I get this bit right?

Thanks for any advice,
Matt

Hiya,
this has come up a few times now. Mr Dracken, (Wynne at JW Motorcycles), is bang on with his figures, but to be honest, no, we don't really bother about it.
All ours have been around 45 degrees so far, except Flap's orange 'un, which is somewhere between 45 & 50, (never leave him in charge of a tape measure). Our chosen style incorporates wide bars anyway, but Lunatic & PD recently tried a pair of standard clip-ons on the rolling MMMotors trike chassis they bought from Toad &, rolling it down the hill outside their workshop, it cornered fine. Yeah, I know that's hardly an accurate test, but they certainly weren't wrestling with it. Yes, it's heavier than a standard bike at low, carpark type speeds, but then you're not holding the weight of the vehicle up, just sitting there, pushing on the bars. I wouldn't call it difficult handling, just different. The more radical you make your vehicle, the more compromises you have to expect in it's handling, but I'd say, unless you have an illness or injury that affects your upper body strength, anyone could ride any of ours -we're certainly not Arnie Schwarzenegger lookalikes! 

Depends what you want to do a bit I guess - Gertie has standard bike front end and the steering is heavy particularly at lower speeds, it's not a problem you just get uysed to it - till the arthritis gets worse and you find that you're just getting too tired on long trips (speaking personally that is).

I've always found bike riding far more physically tiring than driving anyway.
Standard raked forks have their drawbacks too. They're not as stable -they're more prone to rear wheel bump steer, (if the back wheel hits a bump or pothole, it'll shake it's head quite violently). More rake will stabilise that. Bike/trike conversions typically keep the front of the frame unaltered, so have standard rake. You'll often hear their owners complaining of front end wobble during decelleration. Ours don't seem to suffer from that, which I put down to the low headstock height & rake. Bike/trikes also keep the standard bike saddle, which is much taller than ours, so the centre of gravity's completely different.   

ohhh now this is a intersting post
this is covering all the stuff i need to know right now  ;D
im going to be starting my trike frame buil in the next few weeks  :o

I'm sure someone else will come on & assert the complete opposite!
At the end of the day, as long as it's built safely & the style & build quality are to your standards, the rest is just down to personal taste. As I said, if you want radical, be prepared to compromise a bit. If you want utterly predictable, buy a nice little hatchback.  :)

Or a moped!

Must say I never found it so, but then the GT is incredibly stable and designed for riding long distances.

Gertie definitely does the rear wheel steering thing but you learn how to ride to avoid it.  I don't think I get the deceleration wobble though.

I say I don't think, cos all these problems are quite easy to compensate for, so after a while you simply don't notice them!  Rather like, many years ago I had a Moggy that jumped out of 2nd gear and when someone else drove it I forgot to warn him - I'd got so used to stopping it doing it that I'd forgotten the problem was there!

 ;D
I find all biking more tiring than driving, doesn't matter what bike I'm on, it's just that constant battering by the wind, road noise etc. 100 miles on 2 or 3 wheels feels a lot further than 100 in a car. I still prefer the 2 or 3 though.  :P

biking/triking will always be more tiring as we all have to hold on more, just dont do that in a car

A greater level of concentration needed too. Can't multi-task like you can in a car -making a phone call, eating a donut, picking your nose etc.

:) rolling a J :)

hey i can pick my nose and ride the trike at the same time  ;D ;D

Me too! an smoke a ciggy but not at the same time.

I have some steering wobble mainly when I let go of the handlebars.

Rake is 35 degrees I think , got a diagram around here somewhere will post if I find it.

I have 44" wide bars to help with the cornering at all speeds.

nice pic :) like the brass work ...did u buy the brass or aquire it :) are u looking for brass still ?

Always looking for brass VB the bit on the tank I actually paid for (strange as it may seem)

Nice sticker on the tank Doc!
That's another point to remember if riding a trike for the first time. You have to physically lead the trike into bends -obviously you can't lean it. The faster you corner, the harder you have to push on the bars to keep it on line. So wide bars give you more leverage. Careful though -charging up to a corner & throwing the bars onto full lock doesn't guarantee you'll actually go round the bend, (if you're not there already). Two big fat car tyres, running in a straight line, will cancel out the single, skinny bike tyre up front & send you heading straight across the bend & into the ditch on the other side, if you're lucky.
Be very careful please all you budding builders, till you've learnt your machine's quirks & foibles. 

Which is why having Earle's type forks with a wider tyre is better for trikes.

like this......

Charging up to corners too fast will make your sphincter grab the seat (believe me)

My, that's an impressive front end.  :o

Tis at that.

This will be one day.

Twisted Patience (the trike) is a  work in prgress and I reckon always will be, but he overtook me several times on the way to Cornwall!

He can smoke while riding but he has to stop to roll em!

True but I must try harder to roll them on the go!

Roy Rogers could roll fags while riding his horse. Bet he couldn't do it on a trike though.

maybe some of this might catch yer eye?

Oo er! gimmie, gimmie, gimmie, .................................what you after then?

hmm dunno :) maybe better if i bring it all down u can ave a tidy look at it ranges from 1mm-12mm i think quite alot there as u can see..

Sounds good to me.

Have you got a brass mine in your valley then Gareth?

right soon as know ive got a day free i'll pm u sort summut out for a visit :)

Kool!

nah mainly coal up here, that lot is a small part of my late dads collecting habit from the steel works!!

Just to bring the discussion back to trail for a moment, I was having trouble calculating the trail figure for the girder-equipped trike I'm building. The Choppers 101 site has a very easy to use calculator that might help people, but I found that there was no substitute for mocking-up with the actual ride height and seeing what string and chalk gives you in the real world. I was searching for the 'correct ' figure of say, 4" or so, but then the technical gurus on the chopperbuilders trike section site said that I should be looking for an inch or so (Story of my life...) to make the steering lighter and yet still stay stable. I mocked up the chassis, forks and wheel and measured the actual trail from full compression to full rebound and found that I had to move my top pivot forward a 1/4 inch to achieve the right result.( I have a 40 degree rake). Now I have trail of 1" at full extension, gradually lengthening to about 4 inches as the 5" of travel is used up, which will hopefully make it stable under heavy braking.

Interestingly, despite very careful measuring I was not able to replicate the figures that any of the internet trail calculators gave me in the real world with my combination of parts.

 

girders and springers aside.... raked yokes...

excellent for bringing trail numbers back into line on many customs. yes fit them to a standard rake just so you can fit 6" overs and stay level is bloody dangerous as it can easily knock your trail the other way, making a supermarket trolleys handling seem like a formula one car.

these people explain it better than i ever can. the chopper hand book is like a bible ;D

http://www.chopperhandbook.com/neatstuff/index.html