Recumbent trike project – Engineer and general tinkerers advice welcome?

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  • Recumbent trike project – Engineer and general tinkerers advice welcome?
  • Im planning on starting a project to build a recumbent trike. However while I can weld its feel like I am out of my depth to start from scratch. After seeing kite buggy for sale it struck me that I might be able to able one for use as a recumbent trike.

    There are potentially 2 ways I could go about this. One to reverse the usual direction it was designed for, fit a mtb rear swingarm on the central bar, then you have rear supension and it can be driven by the rear wheel (In a tadpole style. The wheels would then need a pivoting joint welded on the end, but I believe it is within my abilities.

    The aternative is to adapt it to a front wheel drive design and add a steering mechanism which would be relatively straightforward.

    Example of a buggy
    An example of a FWD recumbent

    Premier Icon matt_outandabout
    Subscriber

    Bencooper to the forum, bencooper to the forum.

    PhilO
    Member

    The geometry of a tadpole trike’s steering is quite complex, and requires very accurate welding. I’d have no hesitation in building a frame from scratch, but wouldn’t want to try that bit as part of a first build!

    Going FWD is an interesting idea, though. If you try it let us know how you get on. You could try adapting a Cruzbike kit for the front end: http://cruzbike.com/conversion-kit

    nickjb
    Member

    The chassis of a recumbent trike isn’t that complicated. I’d be tempted to start from scratch.

    bencooper
    Member

    I’ve built a couple of recumbent trikes. The tadpole design is difficult – the steering arrangement is complex, and you need to build both the frame and the kingpin system to pretty high accuracy. There’s lots of machining required. If you’re still keen to do it that way, find a book on race car dynamics and read up on Ackerman geometry and the like.

    The other configuration – delta, with two wheels at the back – is much easier to construct as it just has normal forks with a steering link. You do need to work out the drive system via a diff or just single-sided drive, but that’s a lot less complex than tadpole steering.

    I’d rate a tadpole trike as at least 3x as difficult to build as a conventional recumbent bike.

    Is tadpole the name for two wheels at the front and one at the rear ?
    If so, you’ll need a differential for front wheel drive.

    How does this work ?

    The cassette and derailleur must turn with the wheel, yet the cranks are attached to the frame ?
    Does it just rely on chain flex and very limited steering lock ?

    bencooper
    Member

    Yes, tadpole is the kind with two front wheels.

    There have been very few FWD tadpoles – the Russian Berkut was probably the most common. It’s a whole extra level of complexity as you need a diff (or double freewheel) plus UJs at the steering ends to transmit the drive. Almost all tadpoles are rear wheel drive.

    That FWD bike just relies on the twist of the chain to allow steering – you don’t need all that much steering on recumbents, so it’s fine for most uses.

    There is a guy on you tube that does a front wheel drive tadpole trike, but that is a whole new level of complicated. The front wheel drive recumbent i linked doesn’t appear to have a very good setup on the front compared to what can be done. I will find a better example as that would restrict steering quite a lot.

    Premier Icon ratcatcher
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    A few years back I made a flevo bike recumbent Front wheel drive and am sure I have seen a trike version ( not tadpole)the only more complex part was the central pivot but even that was basic lathe work

    meant to also say the complete plans were all on line, can’t remember if they were free or a few pounds but very cheap.
    :-).

    bencooper
    Member

    There have been a few FWD bikes which used a UJ at the head tube with two stub axles to transmit the drive – the only trike I can think of like that was John Bradshaw’s Avant, which was a narrow leaning delta with a short wheelbase.

    In order of complexity, recumbents go like this:

    RWD recumbent bike
    FWD recumbent bike
    Delta trike with single-sided rear drive
    Delta with double rear drive or front drive
    Tadpole with rear drive
    Tadpole with front drive

    And adding suspension is a whole other world of pain 😉

    Edit: oh yes, there have also been Flevo-style FWD trikes. They have the advantage that you can sometimes get them to lean in corners. The downside is they’re distinctly odd to ride!

    PhilO
    Member

    @MTG: Yes, it works on chain flex. That design will have limited lock because it’s using a chain ring for the idler. By using two small idlers near to the steerer axis, surprisingly good steering lock is possible. Have a look at the Zox bikes for example: http://www.zoxbikes.com/zox-26-2/zox-26-low/

    @OP: Have look at the plans on Atomic Zombie

    bencooper
    Member

    I’m also building a Thunderbolt trike for a friend – you could have a look at the plans for that to get an idea of the work required:

    http://www.ihpva.org/Projects/PracticalInnovations/index.html

    They look great fun, but what are proper ones like to ride? I’ve been on small hire recumbent trikes in both configs and the 2 wheels up front felt more stable.

    This looked a hoot:

    Premier Icon oliverracing
    Subscriber

    That fat trike looks bloody awesome! (if a little odd/heavy) – I have been planning on building a recumbent trike (tadpole RWD) for a few years, to go and do a bit of rough stuff touring on – but other bike building projects have always seemed more practical at the time of building – I guess I’ll eventually get it built – but first I need to decide on frame material!

    Saccades
    Member

    that snow one is a daft toy, all th weight at the back on the 1 wheel?

    PhilO
    Member

    A daft toy? It worked well enough to be the first ever human powered vehicle to be pedaled to the South Pole. I got a close look at it last weekend, incidentally. Nice bit of kit.

    The standard ICE trikes ( that’s Inspired Cycle Engineering, BTW, nothing to do with frozen water!) are an absolute blast. 😀

    bencooper
    Member

    that snow one is a daft toy, all th weight at the back on the 1 wheel?

    It’s actually pretty much equally spread between all 3 wheels.

    You haven’t lived until you’ve taken a recumbent trike down a fast dirt track, doing 3-wheel drifts around the corners 😀

    So Ben, What about building a standard recumbent but with some kind of stabiliser system?

    Part of my interest in them is to build a weatherproof shell for use as a commuter vehicle. The issue with a standard recumbent is stabilising yourself when you stop, or designing a waterproof body that still allows you to put your legs down.

    I did find some stabilisers used for racing recumbents but looked not effective enough for stopping and starting regularly

    bencooper
    Member

    I’ve only seen them issued occasionally on racing recumbents, but usually you either have spring-loaded foot flaps or just hope someone catches you at the end of the run 😉

    The bigger problem is that fully faired bikes are pretty much unusable on normal roads – they’re very prone to side winds. However a nose one gets you 90% of the weather protection and is much more practical.

    Or, if you do want something fully enclosed, have you seen the Alleweder kit I do? You build it yourself, but someone else has done all the hard work of designing the full suspension trike geometry.

Viewing 19 posts - 1 through 19 (of 19 total)

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