Two engines, one bike



I looked through the FAQs and did a search but could not find anything on this subject. Has anyone experimented with two rack mounted engines, front and rear wheels? It brings up all sorts of possibilities. An engine assist engine, small engine for street, bigger eng. for trail-off road use, added power for hauling loads or trailer, spare engine for long trips or back country traveling, could have the belt disconnected on one to stay in compliance with cc limits and can still pedal, less wear and tear on spokes if both wheels are driving, two completely separate systems so a complete set of spare parts would be available. I don't know how each engine would act if assisted by the other engine or if this whole scenario is even possible and that's why I'm asking about this. Both could be belt driven or friction/belt combo. Each could be geared differently. One engine could be left idling when in hilly areas to be used when needed. Are there any pros or cons or additional ideas? I am a 71 year old hunter and this would be extremely advantageous for me as I need extra equipment and often travel alone.
Last edited by a moderator:
:cool:Hey Ken,

A fellow member mentioned a tandem project a week or two ago. I'd recommended running a 25cc ROBIN or HONDA 4-stroker up front. I'd also suggested a 2.2hp MITSUBISHI for the rear, but a 32cc ROBIN/HONDA 4-stroke makes more sense. Both engines can feed off the same auxiliary tank.

While cycling uphill and on the trail with a full load, twin engine drives would come in handy. This is especially for a senior citizen pulling a trailer for the deer you shoot.

If both drive systems are same, like STATON or GEBE, one set of tools and each drive system being spare parts for the other drive, like you mentioned.

If you choose STATON'S gear chain drive with reverse gear, you could be charging your camping gear's electric batteries while riding to your camp grounds.(Reverse gear could be rigged to drive an alternator.)

sounds do-able, and practical.

Last edited by a moderator:
I like the idea of a twinnie bike - stanton or gebe would work well in that situation.

Personally I would use the front engine as the main one with the second rear engine as secondary... FWD being more efficient that RWD..

There is one issue that worries me however considering the rider and the activities is the range of the machine... and its not that it wouldnt be capable its more what *could* happen in the situation of an accident or incident..

If we assume a flat road range of 60 miles unladen ... the we can assume 40 or so miles maybe as a cross country range... so what happens if there is some sort of serious problem ... even without a aux tank you could be 20 miles plus from the road...

having a bike die when you are on a road in the UK in most cases is nothing more or less than very annoying and frustrating...

having a machine die in the middle of a forest or there being an accident could be a whole lot more serious... I wonder if in some situations the very ability of these machines might be a double edged sword...

Jemma xx
I forgot (sorry about that) to mention that I already have a rear mounted GEBE R/S 35 and was thinking about another 35 or maybe a Tanaka 40cc two-stroke on the front. If I go with another 35 on the front I could carry a gallon of reg. gas with me and not worry about mixing. With the Tanaka I could carry a half gallon of reg. and a half gal. of mixed. My big concerns are has anyone tried this? Did they work together ok? How about two separate gears (one trail, one road gear) either one could be used as the main engine and the other, idling, used when necessary. I don't think the speed would change much but the power should be improved at low speeds. Is that correct? Thanks Myron and Jemma for the quick response. I have only had my 35 a few weeks and am extremely happy so far. It's a good set-up.
:cool:Ken, I think you could go to ROBIN 25cc for the main engine, and make your 35cc the backup powerplant.

Both engines feed off the same 1-2 gallon auxiliary tank, mounted midframe. No premixing needed. Simply cruise into the gas station, and fill all THREE tanks.:eek:

That'd be a sight to see!

Right, if the set-up works! I will have about $1700.00 invested so I would like to hear some more about any problems I might encounter. Am I the first to try this? Engines, belts, clutches should all last longer. Since both wheels will be pulling during hill climbing and heavy load periods, the pressure will be on 72 spokes instead of 36 so they should last longer also. The more I think about this the more enticing it sounds. I weigh in at about 200 lb.s + extra gas + extra engine weight = two 35cc's may be the better choice?
Something else, when doing my everyday runs over flat country, I can disconnect one belt and tie it out of the way. This keeps me street legal as an under 50cc bicycle. The other engine is a "spare". Off road or in the woods, who cares? I can travel on logging roads as a bicycle where cars and motorcycles are not allowed, such as closed gate areas. Tie BOTH belts out of the way and I AM a bicycle. Any thoughts on this?
my only thought...matching and synchronized front and rear...2 GEBE tanakas would rock my world...great topic :)
By the way, Jemma, "Twinnie" is a good name. Thanx. Or "Double Barrel", Etc. Etc. My wife (Japanese) calls it "Mondai" - Trouble.
Augidog, I think Syncing them would not be necessary as both engines would be assisting each other. Think of it this way. I am on one engine and the other is idling. I come to a steep hill and when I get too slow, I ease the second engine in. If I am right BOTH engines should speed up? I hate to spend that kind of money just to find out I am wrong....
Last edited by a moderator:
sure...just like pedaling and motoring, you can find the balance...however, you may be putting yourself in a situation where one drive outweighs (therefore negates) the other, and you find yourself using one or the other instead of both.

imo, identical drives is the only overall-practical way to accomplish real dual-drive.

EDIT: if i'm correct, it also means the weaker drive will be a drag on the stronger, making matters even worse.