MOTORED BIKEs, About to give up!!!!

Discussion in 'Transmission / Drivetrain' started by MOTOMTB, Oct 12, 2014.


    MOTOMTB Member

    Ok, guys. I've been doing the motored bike thing for a few years now and I don't know how I'd live life without one. My latest bike is a completely custom built frame and bike that is so awesome to ride.....when it's up and running.........:p but I have been avoiding an underlying issue with this whole motored biking thing this whole time. And that is......................wait for it................., the traditional drive train and derailleur system.

    I think I've stopped counting the number of times I've had derailleur issues over the time I've been motor bicycling. Each time I get things fixed I continue with the hope that it won't happen again, that the random branch won't get stuck in my derailleur while I'm deep in the bush and completely twist everything to ****. But it happens again and again and now I'm done with it. The engineering testing and research that I've unintentionally been doing over the last few years has come to an end,.... and the verdict is, the traditional bicycle derailleur and drive train is just not reliable enough for motored power and is too susceptible to damage while on the trails.

    So, I just don't see many alternatives to the standard derailleur system, at least that are cost effective. Sure, I've heard good things about the rohloff but cost wise, just not worth it. The only thing I can think of is an N360 hub but I have my doubts to the durability over extended time and I don't like how it increases friction in the drivetrain system. I'm about to give up, should I give up....what do you think? This motored biker is about to close shop and part everything out, I need some support....:)

  2. troyg

    troyg Member

    Deep in the bush is one problem, trail and street is what a common MAB excels at.If you must stick with a standard DF bike, maybe look into an old sturmey archer 5 or 3 speed, lace it to your fav rim and no more snags.Even after decades of use those old AW's are near bulletproof, plenty of range (for most riding) and it sure is nice being able to shift while standing still.Other than that, a motoped sounds like what you need.

    MOTOMTB Member

    Dude, I basically built a motoped but with almost a full range of gears and way lighter, that's what kills me the most, when it works, it's the perfect motored biccyle. You mention motopeds, but they are not motored bicycles, they're just motorcycles with a ****ty pedal option with no gearing, not quite what I'm after.

    lol, never even heard of Sturney archer, but just did a quick ebay search and they look too good to be true, IGH for 120$??? what is the ratio compared to a normal cassette? anyone have any experience with them? Give me the full scoop. I have my china girl modded but obviously it still doesn't put out a whole lot of power, I'd say maybe 3-5HP. Just enough to get me where I want to go. Can these things handle motored power?

    A little more hopeful now....thanks :)

  4. troyg

    troyg Member

    WOW WOW WOW! That's gotta be one of the coolest MAB's I've seen!!!I don't think a sturmey is going to fit your needs.It's probably just that a bike drive-train is a bit too dainty for your set-up, regardless of internal or external shift.Sturmeys (old ones) sometimes slip out of gear (neutral, freewheel, no resistance) if not adjusted perfect, with your bike that could be a bad scene.If you could hybrid moto and bike gearing somehow, but that's above my mental capabilities.
    How much do you have in that beast?It's super cool man.

    MOTOMTB Member

    Eh Troy, how goes.

    Thanks man, quite a bit of R&D over the span of a few years. Long story but the picture pretty much sums it up. Like I said, I have it engineered to the point of perfection, have been testing, breaking and fixing all the issues for the past few years BUT this stupid derailleur issue is going to basically kill everything. I'm just stumped. If I had the time and money, I'd set out to design a supeior IGH but that's not going to happen anytime soon. I'm pretty sure a Rohloff would work but at their price, just not willing to do it.

    Well, it's just such a **** off because like I said, the drive train basically holds up fine, and I've beat the $hit out of it at some points, it actually surprised me how well the chains held up, cassette, bearings and all that. BUT what happens is that you'll be out in the trails, for instance in the fall on a rough trail and as soon as any little piece of debree, a branch, rock whatever get's into your casette and you don't notice it, things just rip to $hit in 2 secs and then your stuck. The derailleur and cassette are too exposed.

    An IGH is what I need for this rig, but the problem is finding a nice balance of cost to reliability. The Sturney looks cool to me but would it hold up, for 150$ I'm doubtful?? The N360 I'm hearing is hit or miss and the Rohloff is basically a motorcycle transmission in a hub which is what I need but it's just too expensive.

    So guys, chime in, let me know what you're thinking. Is the end for the "Motopedal" (that's what I call her :p), am I going to have dismantle her and sell her for scraps? She's giv'n me a lot of love over the years, a lot of pain too but more love.
  6. troyg

    troyg Member

    I believe you may be over thinking it, beside, you'll never get back the $$ and sweat you put in.
    Exposed cassette/drivetrain is the problem, a plastic dish (cake pan style, lexan being best) some carbon fiber rods from, balsa, zip-ties, epoxy, and you've got a cover.Look at the old oil-bath enclosed chains
    on vintage city bikes for ideas.I'd do everything in my capabilities (yours appear substantial) to keep that ride,
    currency is only losing value, you'll kick yourself if you sell that.The frame has many options.Good luck.

    MOTOMTB Member

    You know, I was thinking of that, some way to completely protect the drive train, some sort of cover. You're right, it's essentially the root of the problem. I'm a CAD designer so I can probably work something with 3D printing. Thanks for the input about selling the bike. The plan would be to part everything out anyway and keep the custom made bits :). I never sell my prototypes, just the copies. Thanks for the input, helps alot! Cheers.
  8. troyg

    troyg Member

  9. HeadSmess

    HeadSmess Well-Known Member

    derailleur...archaic gear shifting at its most refined :) just one step away from crash gearboxes and dog clutches :)

    sturmey archers...awesome:). heavy:(. compact:). large:(. low maintenance:). dont ever try and pull a 9 speed apart:(.you wont ever have to:).expensive, initially:(

    the internal gear hubs have come a lot further than the days of yore. what...up to 15 speeds or something? all ratios are usually listed.

    but even a simple two speed kickback hub is more than enough on a motorised pushbike(extra low and low) and has a saving grace over standard hubs...or gear shifting in general... no linkages! no cables! no flimsy chunks of metal waving around, waiting to get smashed off!

    the internal gear hub has a habit of reaching for high gear when this happens.
    the derailleur can go either way, or be a complete write-off. worst are the frames with integral shifter mounts.damage that and the whole frames ruined!

    the hub gear just needs straight chain, and a decent cage over the shifter crank assembly, be it sturmey archer or shimano or whatever...

    the shifter adjustment is virtually set and forget, and is far simpler than a derailleur! not that theyre hard anyways ;)

    derailleurs self tension. hub gears need a separate tensioner.

    the hub gear can be a completely different size to the existing dropout widths.

    the higher geared ones could be a right pain in the butt for attaching sprockets to.

    you gotta learn how to, or pay to have someone else, lace up the wheel and hub.

    nothing preventing you from keeping a 3 gear chainring upfront other than the need for the tensioner jockey assembly off the derailleur on the rear still:(

    MOTOMTB Member

    Shimano Nexus looks promising....hmm.
  11. Fabian

    Fabian Well-Known Member

    Are you sure about your comment, because i have completely engineered out the unreliability of a conventional rear derailleur system.
    Secondly, i prefer the exposed drive train method because it's fixable on a trail, should you have a mechanical issue, whereas an internally geared drive train will leave you up a creek without a paddle if the hub suffers an internal failure.

    The below links are but one demonstration of the reliability of a modified external rear dive train system.
    The second last photo of the first web link shows the system operating with good efficiency even when packed with snow, though most of it had fallen off the drive train by the time the photo was taken.

    MOTOMTB Member

    You obviously aren't riding the same trials the I do, or to the same degree. I ride my bike like a dirt bike. If you ride on flat paved roads with minimal debree, no, you won't have a problem. Like I mentioned before, the chain and derailleur in themselves are quite strong and will hold up to quite a bit of abuse and torment.....suprising actually, the problem is with debree in the trail, introduce the smaller little branch that throws the chain out of whack, or snags the derailleur and Bam. Gonzo. That's where the unreliability comes into play.

    Actually, I love the derailler setup so much, I'm leaning towards that or nothing, i.e, I will probably keep the system and try to make some kind of cover or cage. Otherwise, the project get's scrapped and I'm parting things out.
    I just don't think an IGH will hack, they're more weight, more complex, sort of weighed the pro's and con's and it doesn't pan out.

    The problem is, making a derailleur cover that looks aesthetically pleasing is going to be tough. I will probably design it with CAD and 3D print it. Stay tuned.


    She'll climb a mountain...literally.
  13. Fabian

    Fabian Well-Known Member

    You have described the solution. Now go ahead and make it happen, because whinging about the problem won't make the solution materialise out of thin air.

    I ride similar trails, but do so with a trailer that carries safety gear and a bunch of spare parts as well as photographic equipment and food/drink supplies.
    Riding like a banshee under those circumstances is not possible, and in my particular situation, it is not desirable because i'm out there to experience the magnificence of the scenery at a pace where it can be viewed to be enjoyed, such as these rides,

    Although your bike looks like a well engineered machine, the Motoped concept much more closely fits your requirements.
    Last edited: Oct 14, 2014

    MOTOMTB Member

    Not really a comparison though. My bike is more of a mountain bike with wheels, the motoped is more of a motorcycle with pedals, heck they even sell a foot peg kit for it. I love the motoped, I will get one eventually but I have a few modifications I would do to it, and the first thing that would go is that heavy ass 4 stroke, I'd replace that with a Honda CR85 2 stroke race engine, to me that would be the perfect coupling of bike and engine but there's no way they would have been able to mass produce it using that engine option while keep the costs down...

    MOTOMTB Member

    Plus, I sort of already have a motoped, but to me, it's a little better.
    and the best part, it's my own company )