A possible solution for one-sided axles for a tadpole trike...???

Joined
Oct 14, 2020
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5
Hello inventive people here,

(Fistly a note, who i am. A 60 year old cyclist, 100s of 1000s of kms on the legs on bicycle-touring for decades, and he likes to experiment with things DIY. I am in the mood to try a DIY tadpole trike, in a way to be as simple and as cheap as possible, so that after a possible success i can offer plans/instructions to the community. With no rush, i do my research and work in free time, i am searching for a couple of months now on the web, i found this forum, good ideas in here, and feeling grateful i'd be glad if somebody picks any good idea as well.)

Anyway. With this post i want to make a question: do you think that the concept i describe is worth? The concept:

My main concern seems to be the so-called "one sided axles" (or stub-axles i think) for the 2 front wheels. I find many people worrying about this. I have found a couple of reliable solutions, but the problem is that they are quite expensive here, but my intention is to offer an effective and cheap solution for people to make with simple tools.

We can find already one-sided-axles on normal bicycles? Yes: the pedals. Can we exploit them? ... Having cycled over uncountable mountains and standing on the pedals quite much and with high power when young, i never ever ever had a single case of pedal failure even with cheap pedals. That tells me that the pedal is strong enough to withstand cantilever force (it is the right term? my english is not perfect) -- which is exactly what we need. The attachment of that wheel to the trike seems easy: it would be simply a job of welding a piece of a bicycle crank.

So let me take a cheap plastic pedal. (-see the attached 3 images-) I cut off the central part of the plastic body, and with a knife i carve it so as to keep only the part to support the two bearing beds. I slide this plastic piece inside a piece of steel handlebars of the proper length, so that it fits snugly and tight inside. I must file off a bit the circumference of the two bearing beds, and they sit nicely inside the steel handlebar piece and on the plastic support, on both sides. I add the rest: balls, cone, stopping washer, fixing nut. I adjust the bearings. I add the end protection cup. (No grease, just testing now.) The thing spins like a charm. Two flanges can be welded on the handlebar piece, on the one side being wide enough to accommodate a piece to support the disc-brake rotor (- spacers weld-jointed with bars). Lastly, the central plastic support part can be permanently fixed in the steel handlebars piece with a dozen of screws inserted through the steel in the plastic, and the holes for the spokes will be drilled on the flanges.

A good question:
-- OK friend, the axle may be strong, but the small bearings will be worn off soon.
A possibly good answer:
  • a brand new pair of plastic pedals costs less than 3 dollars,
  • the dimension standards of these cheap things are the same on the planet and easy to find everywhere, and,
  • the job to replace "2 axles + 4 bearing cups + 52 balls" is a matter of half an hour at most and with very simple tools.
I have no idea about trikes, i have never ridden one, i have never even seen one in reality... so what do you think about this solution?

Thank You.

image 1

image 2

image 3
 
Joined
May 31, 2013
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South Benfleet, Essex, England, UK
Yes, this has been done many times. See this c.2010:
 
Joined
Oct 19, 2012
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Wakefield, UK
The problem with this is getting an axle long enough. Many pedal axles are too short to give good spoke angles. Some old time pedals have long enough axles.
 
Joined
Oct 14, 2020
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5
Thank you both, you made my day! :)

@Popshot - I do not think the length of the axle is a problem, i have been always lacing the wheels myself, and even for racing cyclists and for heavy loaded touring, i never had any issue with side-way-stability of wheels, and this is a parameter i always take into account. Also this number actually may decrease with wheel size and for a 20 wheel there is certainly no problem, taking into account my mild way of driving.
 
Joined
Jan 16, 2011
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323
Location
Vilvoorde / Flanders / Belgium
I like the way you think. But it's a lot of work, a lot of time for something that involves your own safety.

One sided axles for a tadpole trike. Simple, get a decent BMX hub.
Or the SA 90 drum brake hubs. It's not difficult to change the 9-10mm shaft to a 15mm shaft. Just change the 6000 2RS bearings to 15268 2RS bearings. And make a new 15mm shaft.

Even simpeler, buy a set of trike SA 90mm Drum brake hubs. Then you have a right and left variant. With 36 spokes , even 26" wheels can be strong enough.
 
Joined
Oct 19, 2012
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Location
Wakefield, UK
You say you've never ridden a trike. I assume therefore that any wheels you have used have been used as the manufacturer intended on a two wheeler that leans perfectly into a corner keeping all forces running perfectly down the wheel. Side loading simply doesn't exist on a two wheeler. A trike (unless a tilting one) places substantial side loads on the wheels just like a Go-Kart which those wheels were never designed to take. On a tadpole trike it's adviseable to keep the front wheels to 20" max as bigger wheels have a bigger tendancy to fold in the corners due to the extra leverage plus bigger front wheels take up more space when turned so the trike needs to be wider to accomodate them. Some people have used bigger wheels without folding - much will depend on how hard you are in corners and how potholed the roads are. As well as keeping to 20" the more spokes the merrier to resist that loading. Reducing the hub width will have a substantial effect on a wheel's ability to remain round as it removes the spokes triangulation.
 
Joined
Oct 14, 2020
Messages
5
Thank you for your remarks.

You help me understand how a trike works. I see the peculiarity of lateral loads.

In case i choose the solution above, i'll keep a good flange width, as it is not restricted by the length of the pedal axle. And yes, this will be under the condition of relaxed/conservative driving, which is actually the reason i decided to use a trike and not one of my upright rockets. :p
 
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