Is this a real problem?

[jonrev]

I've been reading a thread on ES from a newbie trike owner which sounds a little worrying. Haven't read similar before and just wondered if the phenomenon the OP describes (and others seem to acknowledge) is worth trying to design out of a build. link https://endless-sphere.com/forums/viewtopic.php?f=51&t=115857
I hope I have posted a link to the thread and would like any comments.

Thanks

John

 

[DannyC]

I would think there's a few things all working against that trike's success.
I think a FWD hub motor on that big wheel will want to go all over the place and be almost impossible to wrangle into a straight line and the rider will be fighting and correcting it at every bump it encounters.
Big balloon off-road tyres will be harder to steer or correct and will want to go in their own self-steered direction and you would be fighting them all the time.
It also has only one rear wheel driven not both, and while this isn't a big problem it certainly won't help.
The trike is a bit of a "mugs-eyeful" all show and no go IMHO.
The gentlemen of the "English Trike Association" would probably have much to say about this oversized American Blimp.

 

[Popshot]

Removing or reducing trail may assist the issue of wanting to steer downhill but will almost certainly make the steering anywhere from livelier through skittish to dangerous. Whilst the tendancy to steer downhill on a camber isn't desireable the wider requirement for steering stability will likely dictate trail requirements.

 

[jonrev]

Thanks Danny. It did seem odd that a problem like this didn't seem to be mentioned in any other threads I've read but all those that responded seemed to be accepting that the trike would be a pig to ride and that's normal.
Thay also seemed to be saying that having any noticeable trail on the wheel makes the problem worse and setting the forks up for very little trail is best on a trike. That does seem to make sense I guess as any camber will tend to steer the wheel 'downhill' as the weight will be trying to push the mass of the wheel in that direction like a shopping trolley in an uneven car park? Front wheel flop?

Is it a good idea to design in a minimum of trail on the front wheel or does that bring it's own problems?

John

 

[jonrev]

You answered before I'd even posted the question thanks Popshot. Well then I'll just follow the AZ design and see how it feels to ride. I suppose being aware of a possible 'oddness' will be a good thing as I start using it.

Thank you both.

John

 

[maddox]

I did speedread the forum page mentioned.
It seems nobody there knows the difference between an upright delta or recumbent tadpool.

In any case, the customer got what he wanted. A delta with fat tyres and a 750W front hubmotor.

Funny bit. I tried to use a delta upwrong last week..... The enviroment wasn't happy with me. I wasn't happy with the bike either.

 

[jonrev]

Hi Maddox. Can you explain to me what you mean by 'upright delta'. Are you meaning something like the old Pashley 'old persons' trike ie a standard type bike but with two rear wheels? Are yoiu including a regular recumbent delta type trike with a relatively high seating position cos that's probably the sort of thing I'm thinking about for myself :-( No fat tyres but high enough seating that I can lever myself out without help.
Should I rethink maybe going for a tadpole????

Thanks

John

 

[maddox]

If you follow the link to the mentioned bike it's an "Pimped old person's" bike with 2 back wheels. An upright delta. Or upwrong delta if your a recumbent fan.

 

[jonrev]

OK thanks- that's a relief.
You say the guy got what he wanted but didn't he make a fuss about it! Demanded his money back in full or was about to set fire to it in protest and to warn others it was so dangerous it would kill someone! Not a happy chappie.

John

 

[maddox]

He didn't got what he wanted. He wanted a good riding everything including the kitchensink pimped tricycle.
Unfortunatly, tricycles like that ride totaly different than a normal bike.
Maybe it does ride well, but everything points towards "needs experience".

 

[stormbird]

The gentlemen of the "English Trike Association" would probably have much to say about this oversized American Blimp.

Ok that's me then ?

I have some experience of these [ mostly bad ! ]
History ...
I cannot ride a normal bicycle very far before my neck , shoulders wrists and areas below the waist start complaining loudly and frequently.
So despite being lent one of these and many offers of others for long term loan I have never invested any time in learning to ride one ?
So why do they need ' learning ' ? because they are vicious little bas*ards that will not go where you want them to and are patiently waiting for a lapse in concentration to swerve at high speed into the verge.
They ride down the camber ALL the time , if you follow someone riding one of these the front wheel is constantly flicking to the right [ in the UK ] to keep the trike in a straight line on the road [ I think this becomes sub-conscious and they don't realise they are doing it ], still over steep camber is a challenge to the unwary. Having no interest in them I have never tried to analyse why they do that .

Now the good news a recumbent delta trike DOES NOT DO THIS [ well maybe unless DannyC builds it [ he has a knack of building in new problems to proven designs ] Deltas if single wheel driven have a tendency to turn away from the driven wheel however that is easily controlled with just 1 finger on the steering [ Hase Kettwiesel ] and only occurs when pedaling.

Pythons do not do this as the steering is part legs part handlebars.

Paul

 

[DannyC]

Now the good news a recumbent delta trike DOES NOT DO THIS [ well maybe unless DannyC builds it [ he has a knack of building in new problems to proven designs ]

Note: This was a Python trike that always wanted to veer up the camber and across the road into oncoming traffic. Maybe because it was longer than some and had a really good and well-made pivot and not a "kludged" extra stiff pivot.

 

[jonrev]

Wonder why there's such a difference between these things and a recumbent version. I can see that the high riding position will likely affect ultimate stability but surely the layout is similar at ground level isn't it?
If you sat the pilot down at recumbent level somewhere near between the wheels, without any other changes to running gear (obviously not actually possible) would the things still want to send you up the kerb and if so, why is that? Is the steering geometry to blame for some reason?

John

 

[stormbird]

Note: This was a Python trike that always wanted to veer up the camber and across the road into oncoming traffic. Maybe because it was longer than some and had a really good and well-made pivot and not a "kludged" extra stiff pivot.

I think your propensity started way before the Python ?

i.e Wobbly Donkey

I'll get my coat , shall I take the milk bottles on the way out ?

Paul

p.s is Recumbent Trikes UK some sort of Masonic secret society ? seems I can't even view it without rolling up my left trouser leg and singing Land of my Fathers in Welsh ?

 

[stormbird]

Wonder why there's such a difference between these things and a recumbent version.

Life is to short .....

I can see that the high riding position will likely affect ultimate stability but surely the layout is similar at ground level isn't it?

Rolling down a camber is not strictly a stability issue , well at least not till it tips over on the verge

Is the steering geometry to blame for some reason?

Unlikely the picture I posted may have contained normal bikes with bolt on trike rear ends , in other words standard 2 wheeler geometry !
trykit conversions

Conversion axles

Paul

 

[Popshot]

Recumbents generally sit the rider between the pair of wheels. I suspect a recumbent delta has a lot less weight on the front wheel than an upright. Combine that with a lower centre of gravity not acting as a lever to pull the trike downhill on a camber and that probably explains why a recumbent delta has better manners.

 

[jonrev]

Got it! That makes absolute sense now I can picture it in my mind. Keeping the low weight on the front wheel which always seemed like it should be a drawback to me is actually a really good thing in reducing the strength of the 'flop' effect. Together with the longer wheelbase it's effect is even less of a problem. Thank you

John

 

[Tom Schneide]

Got it! That makes absolute sense now I can picture it in my mind. Keeping the low weight on the front wheel which always seemed like it should be a drawback to me is actually a really good thing in reducing the strength of the 'flop' effect. Together with the longer wheelbase it's effect is even less of a problem. Thank you

John

One more thing, on my carbon composite rigid delta I am building I was planning to use a lot of trail. Then realized trail only works properly on tilting bikes/trikes. So now I will use zero trail!

Tom