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Motorized Mountain Bike – Traveling Light

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Motorized Mountain Bike
Motorized Mountain Bike

Every time someone builds a motorcycle, the question of weight pops up. No matter how light you go, it’s always too heavy for someone else. Well, how about 62 pounds?

This home built mountain bike sports a 35cc engine plus:

an 8 speed Shimano hub (Planetary Gearbox) in the back wheel that shifts the gears for pedaling and for the motor, has freewheeling for both engine and pedaling… it can be ‘motored with no pedal movement’, ‘pedaled with no motor crank movement’, ‘pedal assisted when motoring’ and is ‘totally free wheeling when not pedaling or motoring’.

Alexander Kiefer, in New Zealand, wanted something that would get him up the hill as well as down and this is the result. There’s also 5 inches of suspension travel and hydraulic brakes. He can ride his favorite downhill courses as before with no car needed. The motor gets him there, takes him up the hill, he shuts off for the down hill run then motors home. Three liters of gas goes a long way. He says a 100 mile day is a breeze.

Motorized Mountain Bike
Motorized Mountain Bike

Link: Al Kiefer

Related: Project M85 Freeride
Related: Derbi DH 2.0

Posted on Filed Under: Motorcycle Builders

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Comments

  3. Nice work! I certainly appreciate a nice motorized bicycle…and that is very well built.

  5. This begs the question if a bigbore or turbo kit is in the works…. just kidding
    Looks like a very well executed machine that does exactly what the guy wants, more power to him.

  6. Lemme know how that works out for portaging the bike, or for putting on a car-top carrier for long trips.

    But yeah, for what he’s using it for, the extra 35 pounds or so over what a “normal” downhill bike would weigh isn’t a big deal.

    I’m actually more interested in that front fender than anything else. 🙂

    cl

  7. I want one of those NOW .That would be so useful in the city you should start selling them.Keep it minimalist

  8. I think it is a motorcycle with pedal assist and the perfect city commuter. This is far and away more practical than electric and you don’t have to steal electricity from someone else to get home.

  9. Great work!! So, does the American Whizzer Bike have the same engine size? I think there should be a Mountain Bike company that would build these. I hope someone would mass produce them, I would buy one or two.

  11. Drat, he got to building this before I did. I’ve also planned up one using a similar industrial 90 degree drive and moped crank/pulley/Sturmey Archer hub.

    Then there’s the point at which you wonder how hard it would be to fit CRF150 suspension to the moped laying in the corner of the garage…

    -todd

  12. A 35cc engine would be a perfect addition to my Specialized Enduro. Integrating the motor into the carbon frame would be a major problem though. I wonder how is shock is handling the extra lbs? 62 lbs bike plus his weight is probably approaching max for many standard read shocks. They usually don’t work above 225-250 lbs…

  13. A lot more high-tech than my Schwinn/Weedeater I built around 1977….it is in the shed still…….waiting on $10 per gallon gasoline………but it would run 35 mph on a flat surface .

  14. The Whizzer (now made in Taiwan) has, and always has had a 138cc engine. Most places it must be registered as a motorcycle. My home built motorized bicycle is under 50ccs and does not have manual gears. Where i am, it’s treated the same as any scooter under 50ccs, no registration at all. The creation here would fit that definition, but for the gears.

  15. I built my kids (and me) a little 35cc weed-whacker powered go-cart. My son and I hit the bike trails late one night. He was on the cart, I was playing chase on my mountain bike. He dusted me. In 30 seconds I couldn’t even see his tail light. In 20 minutes I couldn’t even smell raw fuel. I’m sure that this bike would lay a beating on Lance Armstrong.

    I like the Norton (fuel and) oil-in-frame influence.

  17. this looks really well put together. the engine looks better integrated compared to other motorized bicycles ive seen. I dont think maxing out the weight limits would be a problem. ive been mountain biking with some big 250+ lb guys in moab utah on some pretty rigorous terrain with full suspension bikes and their bikes held up just fine even after jumps, drops, etc. A rim would collapse before anything happened to the shocks i think

  19. Traveling light is definatley the way to go! this loks too cool! Awesome too the 5 inch of suspension travel and hydraulic brakes!

  20. Makes me wonder its like crashing on a bike that weighs 62 pounds and has hot engine parts sticking off it. But the bike/moto looks pretty awesome and I bet is an absolute hoot to power right up big hills even if doing so voids one of the main reasons I really like to ride bicycles (you know, the whole exercise thing?).

    Still pretty sweet and would actually work really well for commuting too (maybe with some skinnier tires).

  21. Again the local laws may come into play. Will the Greenies let any gas powered bike into their domain? In Michigan anything up to 50cc is ok, but no gears are allowed. Maybe the law would look the other way for something like this, obviously an assisted bike. But at any rate the idea of keeping a gear choice is very appealing. What a Great Build, and I bet he used a high quality engine and not those $79 chinese toys they bolt on bikes around here.

  23. Top job! It amazes me that more bicycles aren’t equipped with epicyclic gears, makes so much more sense then the deralieur system. I have also had a thought that to achieve 21 or 27 gears, you could have another gear-set in the crank for multiplication. Unfortunately this would result in the front chainwheel rotating at a different speed to the crank, but this could be fixed by partially enclosing the chain.

    Anyways, the point is this. Dad and I made a BMX sidecar when I was 13. I am now 32 and the beast is still alive and well, even after several drunken attempts as a young adult to navigate a local motorcross track with a mate. We fitted a Sturmey-Archer 3 speed hub and never looked back. Low gear is easy for hills, second is 1:1 drive and in top she will do 45km/h on the flat. A very scary proposition. This mountain bike has me wanting to fit a motor to the beast!

  24. “epicyclic gears”?

    I think these are great.

    Now waiting for the shaft-drive to pick-up and suddenly the old pedal bike is as reliable as my new car…

    I think there’s one North American supplier and another in Holland?

  25. That is a serious project, I can’t find any afterthought! It would be nice to see that rear planetary hub in action, though.

  26. Epicyclic = Planetary as far as wikipedia is concerned. I wonder why I chose to say Epicyclic. Nonetheless, the only caveat to these kinds of gears is that it is best to slow or stop your pedalling to allow the right gear to engage. But then again, how many of us have been annoyed at climbing a hill on a roadie or MTB and not being able to get the right gear in time, and if you come to a halt you can’t just select gear X while stopped and start again.

  27. While it may be to heavy for a roof rack or bike rack, there are hitch mounted motorcycle racks that you ride up a ramp to load, unfortunately even the lightest of dirt bikes plus the rack exceed a Class I tongue weight, so you have to have a vehicle big enough for a Class III hitch. I use a small trailer for this very reason.

    I could see a small niche market that wants a lighter motorcycle for various reasons.

  28. I saw something very similar to this about 5 years ago here in Christchurch at a show.
    If it is the same one I saw then the price tag was somewhere around $8-10,000NZ.
    Probably a little pricey for those other than dedicated enthusiasts. Medium sized production runs would be needed to reduce the cost and get more people interested, especially when a DR125-250 can be bought for $4-8000.

  30. I can appreciate the execution of this, but lets get this straight: its a MOTORCYCLE. It should not be around any MTB track or park or ridden on the same tracks at the same time as a MTB. Being powered I bet it would cut the hell out of the tracks, way more than something powered only by legs. It has a motor with hot parts sticking out of it, which implies you should be as worried about crashing it as you would an actual trail bike (lycra and baggies and a bike helmet? Not even a DH helmet? come on!.

    If this guy came past me in Victoria Park I would (if I caught up with him) give him as much crap as I did the kids on those crappy minibikes that were in my local mtb park a year or so back (worse: they were in the exit from that park which is private land and a local landowner graciously allowed the mtb club to build a track on to get out of the park). Last time I nearly got into a fistfight. Hilarious.

    Hell its hard enough to get access, without having some numpty bugger it up.

    Ride it where motorbikes go, I’m all over it, great. but not on my local mtb tracks.

  31. right … and next time you’re riding your car and see a cyclist on the road you yell at him and give him a lecture because he has nothing to do here … whatever

  32. From what I’ve read, it’s perfectly legal to ride a bicycle alongside cars on the road. I’ve also read that you cannot ride motor powered cycles on hiking/biking trails. Maybe it’s me or that big white “NO MOTORIZED VEHICLES” sign at the trail head. I’m more passive though, I just give a slight glare and try to avoid confrontations all the while jealous that I don’t have a motorized bike myself.

    -todd

  34. So there is a problem with him riding to the trail head with the motor, and then him riding downhill under pedal power?

  35. Hi everybody…Al here…that’s my bike. Would have replied sooner..been away…
    Thanks a lot for the great comments…appreciated.
    Chris..that fender is hammered out of an old Alu number plate.
    Houghmade…great bike you build…like that attention to detail..
    AJ…didn’t build it with selling it in mind…but might do, don’t know yet.
    Todd…build yours…it’s fun..
    Pete…I am a lightweight..the extra 10kg of the motor setup shouln’t make any difference.
    Paulinator…it’s not about speed for me here…its as fast as the average road racing cyclist on the flat BUT as soon as we get to the hills it comes into its own.
    Fenriq…actually i can get as much exercise with it as i like…going uphill i can either pedal assist a little or give it heaps..if i put some energy into it she just ‘flys’ up the hill… great fun.
    Tinman…yes that engine is no cheap chinese piece of s..t. Its also a 4 stroke: $500US.
    Kim…comparing 1912 Pierce, 1923 Nimbus, etc. with my bike…huhu..too much.
    WestOf Ben….epicyclic gears..they make them in 14 speed with the same range as MTB’s with 3 chain rings at the front and 8 gears at the back…not cheap, and heavy.
    And yes ..great to be able to change gears when at a stop..
    Doorsonpatrol…that wasn’t me in Christchurch 5 years ago.. but you are right about the cost of limited edition sale…8000-10000$NZ is 5800-7200$US and probably around what it would need to be, unfortunatly…unless you build it yourself.
    Tim…read the post again..then apologise to everybody here because you are spoiling the fun…it says clearly that i turn the motor off for riding MTB tracks, same weight, same tires, same everything as MTB. And you need some glasses.
    Tom…they ARE leather shorts they are great for riding…i cut my motorcycle pants and glued the cut off onto my bike seat…made a toolbag…
    Again…cheers everybody…have fun riding whatever it is.

  37. Hi Ron…the M85 fits into a totally different niche. Fun to build and fun to ride…yes.
    With the M85 it’s hard to find places to ride offroad but with my bike I have heaps of MTB tracks to choose from these days.
    The M85 cannot be used on Mountainbike tracks because it cannot be pedaled.
    And some pedaling needs to be done on many parts of the tracks and motoring is illegal.
    On a recent ride I had to lift my bike (the one in this post) 20 times over fallen trees…hard work but possible while with anything even slightly heavier it would not have been possible.
    28 kg/62 lbs is the absolute maximum one would want to pedal and lift over obstacles.

  38. Hi Al, der erste Beitrag hier mal in Deutsch. Dein Bike sieht echt geil aus, Respekt! Wann gehst du in Serie damit?
    Gruß Detti

  39. That is a true thing of beauty, don’t make it yourself, go into business with an electric bike shop to use their contacts to get it made in china from the imported parts you specify. They would just be doing the assembly then sell it everywhere. I know a guy in Melbourne who had an idea for a design of electric bike that nobody else had made and he did just that. Quite successfull.