Jack shaft drive with smaller 4 cycle engine

[marjamar]

Hello people,

I'm looking to build a jack shaft drive system on my Motobecane Cafe' Express bike. I've been putting stuff together to make something I can use for bike camping and maybe some touring. I've decided to pull a BOB IBEX trailer and have most everything put together and working. Now, I see I am going to have some real fun, but I'm also going to have to work real hard to get to it. At 64, I'm OK with some "real work", but not to sure about how much of it I really want. So, I'm thinking about a little cheating with the peddle power might be a smart move.

I don't want very much noise at all. Don't want anything faster then 25 MPH or so. But want decent power in lower gears to get up longer inclines. So, thinking something along a 29cc 4 stroke, and split shaft drive to the cranks would give my Nexus 8 speed internal hub enough power to cope with most roads and still not be too much to break stuff.

Never done a bike mod like this before, but I'm fine with any type of mechanical, machining, fab work I've done over the years.

What I could use is some good ideas on what parts to look for and maybe even some advise as to the practical aspects of doing something like this. I'm a big guy at about 240 lbs and the BOB trailer loaded will be about 100 lbs. The bike as is, is about 40-50 lbs. So I'm looking at around 400 lbs. or so, without the added motor stuff.

Am I out of kilter here?

-Rodger

 

[5-7HEAVEN]

Hi Rodger,

I believe you're on the right path, similar to one of my builds. The 4-stroke Robin/Subaru 1.4hp engine or Honda XH35 are two excellent choices. Key to an easy install is its 76mm centrifugal clutch and the pocket bike 5:1 transmission. Tranny bolts directly to these engines as well as many others sharing the same size clutch. With your skills, a simple steel flat plate can be bolted under the engine, then welded or bolted onto the bike frame. The tranny adds 3.5" to engine width. If you center the engine, it will position far right and need a jackshaft, your bike will need three chains. When positioned more to the left, a 206mm wide bottom bracket from Sick Bike Products (SBP) will align tranny sprocket with the outside chainring perfectly. You'll then need only two chains, engine drive and pedal chain. HOWEVER, the inner chainring needs to be positioned 1.75" inward. Positioning the engine more to the left allows you to use your local bike shop's bottom bracket. The outer chainring will move closer towards the inner chainring and frame.

You might consider a 2-stroke engine with 76mm clutch. Its advantage is that you can position it 360 degrees, even upside down. I believe you can't do that with a 4-stroker, but I may be wrong. It's much easier to fit an engine in the triangle if you can hang it in any position.

Gearing? A super low First gear allows you to climb very steep hills, while at the same time Eighth gear keeps your engine from screaming its life out in high gear. I use T8F pocket bike chain and sprockets for engine drive. It makes for lower gearing while keeping the chainring about the same size as a stock bicycle one. Using 11 tooth sprocket on the tranny and a 72-tooth chainring spring allows for 32.725:1. Use a 24-tooth inner chainring. Depending on what your hub sprocket and ratios are will determine how low your overall gearing will be.

This information should help you plan what you need.

Good luck, Rodger

Myron

 

[Sidewinder Jerry]

That's a lot of weight to pull up a steep hill. You should consider a 49 cc engine.

 

[marjamar]

That's alot of info. I'll take some time and go though it and check the parts you've suggested. I sure appreciate you taking the time to itemize so well. I'll post back when I've checked some of it and have a few more questions/ideas.

Thanks again.

-Rodger

 

[marjamar]

I would agree simply because I have had some experience in a number of different venues with limited power/performance and trying to complete a task with it. In this case, my primary concern isn't so much brute power, but making use of limited power for a number of reasons.

I would like to do this with the idea of not breaking existing parts like the Nexus internal hub and maybe even things like the drive chain. I figure if I have over 1 HP in the power source, that's far more then my legs could ever produce to begin with, and if needs be, I could provide some added power to the mix with my legs if necessary. But going up a hill in 1, 2 or 3 vs. 5, 6, 7 or 8th really would make little difference as that would still be far faster and far easier then peddling up.

I am no where near convinced my approach is the right one however, so I do appreciate your insight and will do my homework before making firm decisions.

Thanks alot.

 

[silverbear]

You've gotten some good advice backed up by personal experience. We've got some great forum members here and you've just been advised by one of them. But as you say, you need to give this long thought and have a good plan to work with that fits your needs and circumstances. It sounds to me like you've got some grand bicycling adventures in mind... woohoo!
SB

 

[marjamar]

You've gotten some good advice backed up by personal experience. We've got some great forum members here and you've just been advised by one of them. But as you say, you need to give this long thought and have a good plan to work with that fits your needs and circumstances. It sounds to me like you've got some grand bicycling adventures in mind... woohoo!
SB

I would agree. Right place to come. Maybe some day, I can be a bit of a help myself.

-Rodger

 

[BigBlue]

Rodger,

Here's a couple possibilities. Staton is in the process of designing a shift kit for the Atlas cargo bike that he sells on his website. Another possibility is to use a Staton gearbox and a chain drive with a pusher type bike. Those training bikes that attach to the back of the parents bike.

http://www.staton-inc.com/store/products/Atlas_Cargo_Blue_Grey_Black_69143-63-2.html

http://staton-inc.com/photo_gallery_large.asp?PhotoID=48

You might want to consider going electric with a hub motor if you want quietness. Your costs are going to be higher, especially if you go with Li-Ion.

Here's a battery powered pusher trailer that is electric that can carry cargo. The guy sells plans. You could have a local welder build it for you. If you search the site, he built the trailer for the same reason that you had originally posted : http://electricbicycletrailer.com/

A 48 volt hub motor and some Li-Ion batteries and you could have some range with you pedaling.

Good Luck,

Chris
AKA: BigBlue

 

[marjamar]

Thanks for the links Chris. I've looked pretty hard at electric. All the way from simplistic to solar augmented. I used to be partners with my older son in a business that used lipos and brushless motors, so I have for a number of years joked with him about building a lipo/brushless bike. Although some fine and quiet power is there to be used, it is still very costly and for touring, charging needs really put the whammy on most all things electric.

When I first started thinking on motorizing this camping rig, I was looking at alternate methods of using the BOB trailer as a pusher setup. I've come to the conclusion that it's a really fine trailer, but it's design would have to be modified too much for pushing a bike. And with all of the thought put into this, the idea of pushing with a trailer has opened up too many questions about safety for me to embrace it fully.

If and when fuel cells are figured out well enough for conversion of methanol or some other less then hazardous medium, electric setups will be the wave of the future. But until a reasonable on-the-road recharge method is worked out, touring via electric motor is not the right choice -- For me at least.

I'll look at what Staton has on his website.

Thanks again.

-Rodger

 

[curtisfox]

Yep i would go with a 4 stroke it would be a lot easyer to quiet it down and 50 cc Honda or the 4gt (Honda clone will rev the equivelent of a two stroke 7,800 rpm's.
Also if you want quiet the less chain you have the quieter it will be. You could use a wizzer pully on the rear wheel ( i am going with a 24" bike rim for a pully to the rear,like Harry did in the Villers beach cruser ) The 24" rim would mean you would have to cut the frame for clearence like the Matag Flyer,that big rim would give you a low gearing without to many big pullys or sprokets up front. Thats Dax is in Colorado http://thatsdax.com/ He has helped me a lot with parts for Honda...............Curt

 

[marjamar]

A few years back, my older son and I were going to design and build some 2-wheel drive all terrain utility bikes similar but smaller then the Rokon. We even starting buying parts, but business always kept us from really working on the project. Through this idea, I have to wonder now if using a CVT transmission on my touring/camping bike would be a good or bad idea. If I did this, I could go directly to the rear wheel, bypassing the the bikes drive train entirely. This would allow me more freedom in choosing larger power options with less concern for damaging existing components.

Anyone doing, or done any bike setups using a CVT transmission?

Thanks for all the help and ideas so far.

-Rodger

 

[oldtimer54]

I have a CVT build. If you look you should be able to find it. It works fine but I think it would take to much power to run it from a little 4 stroke.

 

[mabman]

That trail a bike on the Staton site was mine over 10 years ago and in fact while I was living in Crested Butte. Really wanted something that I could use when I wanted to and take it off when I didn't. It went ok in a straight line but when cornering it was less than desirable especially if you applied any power as it would want to highside the bike. I now run a BOB trailer with a Golden Motor 1000w 48v and it does nearly what I want it to. Using the axle as a contact point, both sides btw, is much better all around. Working with a friend on the next level of pusher trailer as after all these years messing around with small engines on bikes I still feel that the pusher trailer is a viable concept, for electric that is.

What I am going to do for long distance is to use a GX35, because 35cc is the limit in the state I live, in a friction drive setup. My first attempt at motorizing was a friction drive and it worked really well and I always seem to go back to what works I guess eventually. If you are just looking for a kicker to get your load up the steeper roads you might want to consider a friction drive at least. It doesn't utilize your Nexus but with the right size roller it will definitely help alot especially if you pedal alongside it to keep it on the pipe. Don't need it, just raise it up and go with no parasitic drag. I have been noodling the idea for years now of a two roller setup but have not gotten around to actually doing it yet.



Speaking of pipes the stock muffler on a GX35 is not too loud but you can use this technology to really quiet one down without losing power: http://www.piteraq.dk/flight/muffler.html especially if you point it down at the ground at an angle.

But using a long bike with a motor on it is also a good plan and am excited to see what Dave comes up with down there for that.

 

[worksmanFL]

Rodger,

Here's a couple possibilities. Staton is in the process of designing a shift kit for the Atlas cargo bike that he sells on his website. Another possibility is to use a Staton gearbox and a chain drive with a pusher type bike. Those training bikes that attach to the back of the parents bike.

http://www.staton-inc.com/store/products/Atlas_Cargo_Blue_Grey_Black_69143-63-2.html

http://staton-inc.com/photo_gallery_large.asp?PhotoID=48

You might want to consider going electric with a hub motor if you want quietness. Your costs are going to be higher, especially if you go with Li-Ion.

Here's a battery powered pusher trailer that is electric that can carry cargo. The guy sells plans. You could have a local welder build it for you. If you search the site, he built the trailer for the same reason that you had originally posted : http://electricbicycletrailer.com/

A 48 volt hub motor and some Li-Ion batteries and you could have some range with you pedaling.

Good Luck,

Chris
AKA: BigBlue

That Sun Atlas Cargo is niiice! Looking forward to seeing Dave Statons 2 kit options!

 

[marjamar]

Interesting you have setup your BOB trailer, something I was looking at doing. Couple of things stopped me. The big one was recharge. I was considering running 2-2'x2' mono-crystalline solar panels flat over the trailer on an aluminum hinged frame w/converter to charge the batteries during daylight. But it would still require hours of setting time to reach full charge, depending upon ah size, more then once a day on trips -- Even with a "charging on the run" setup.

Next thing was looking at the hitch setup to the bike. On the Nexus hub, the trailer attachment point seems too weak to me. Attachment to the "Bob Nutz" might be OK, but the angle on the fork hooks is designed to hold tighter with load, whereas in a "pusher" setup, they would actually want to press the hooks up and forward. This would put undue stress on the hitch pins and (in my estimation) cause them to bow out of the retaining hole and detach the trailer, which of course would be a bad thing.

I looked at friction drives, but I think I want gearing.

I'll be doing some type of quieting without a doubt on any engine I use. Peace is the whole idea here for me. Noise, opposes quite quickly.

Thanks.

-Rodger

 

[marjamar]

I have a CVT build. If you look you should be able to find it. It works fine but I think it would take to much power to run it from a little 4 stroke.

Yeah, don't know how efficient they are, but the non-shifting option is attractive. I'm going to do some more research for sure.

Thanks.

-Rodger

 

[worksmanFL]

Yeah, don't know how efficient they are, but the non-shifting option is attractive. I'm going to do some more research for sure.

Thanks.

-Rodger

http://www.youtube.com/watch?v=kVPjhmTThPo

Nuvinci Hub...

 

[marjamar]

http://www.youtube.com/watch?v=kVPjhmTThPo

Nuvinci Hub...

Yeah, I was looking at that a year or so ago. Seems there are 2 camps on it for sure. Pretty divided opinions on it. When I first went to their website, I really wanted one on this bike. I even went so far as to see about getting it custom installed on a Spot bike. That was when I thought a couple grand for a really nice bike would be good -- Don't feel that way so much anymore. I really don't think a Nuvience would be any better (or worse most likely) then an internal gear hub, which I already have, so unless I want to stay away from running the power through any hub, I think what I have, I'd use.

Thanks.

-Rodger

 

[marjamar]

Hi Rodger,

I believe you're on the right path, similar to one of my builds. The 4-stroke Robin/Subaru 1.4hp engine or Honda XH35 are two excellent choices. Key to an easy install is its 76mm centrifugal clutch and the pocket bike 5:1 transmission. Tranny bolts directly to these engines as well as many others sharing the same size clutch. With your skills, a simple steel flat plate can be bolted under the engine, then welded or bolted onto the bike frame. The tranny adds 3.5" to engine width. If you center the engine, it will position far right and need a jackshaft, your bike will need three chains. When positioned more to the left, a 206mm wide bottom bracket from Sick Bike Products (SBP) will align tranny sprocket with the outside chainring perfectly. You'll then need only two chains, engine drive and pedal chain. HOWEVER, the inner chainring needs to be positioned 1.75" inward. Positioning the engine more to the left allows you to use your local bike shop's bottom bracket. The outer chainring will move closer towards the inner chainring and frame.

You might consider a 2-stroke engine with 76mm clutch. Its advantage is that you can position it 360 degrees, even upside down. I believe you can't do that with a 4-stroker, but I may be wrong. It's much easier to fit an engine in the triangle if you can hang it in any position.

Gearing? A super low First gear allows you to climb very steep hills, while at the same time Eighth gear keeps your engine from screaming its life out in high gear. I use T8F pocket bike chain and sprockets for engine drive. It makes for lower gearing while keeping the chainring about the same size as a stock bicycle one. Using 11 tooth sprocket on the tranny and a 72-tooth chainring spring allows for 32.725:1. Use a 24-tooth inner chainring. Depending on what your hub sprocket and ratios are will determine how low your overall gearing will be.

This information should help you plan what you need.

Good luck, Rodger

Myron

Well so far you're ideas here make the most sense to me. I almost hate to ask, but do you know of any in-depth pictures of this setup install, or even better as a build? Couple of questions I have, I'm pretty sure would be answered with a couple of photos.

Thanks again.

-Rodger

 

[mabman]

-Rodger

I can get 40 miles with a 12ah Li battery averaging close to 20mph in hilly terrain out of my BOB before recharging which in actuality uses 9.6ah before the BMS shuts it down. Takes a little under 2 hrs. with my 5 amp charger to renew. This is sufficient for my needs at this time. I wasn't trying to sell you on the idea of a BOB pusher, just making a point that it is a viable option for motorizing a bicycle, in fact most of them including recumbents etc..

An old friend is an engineer at BOB and he doesn't have a problem with the attachment as a pusher. The guy who holds the patent has had moto BOBs in use for the last 12 years. My buddy is the one that is helping me with the new design which may or may not use the BOB yolk and nuts we have yet to decide that. The one that we are using for the prototype stage is from an Xtra Wheel and it is the same kind of thing but different enough to skirt the BOB patent and fully encloses around the "nut". We are not trying to reinvent that particular aspect as much as the trailer itself and its functionality.

Here is a picture of that 5:1 reduction on a 49cc Huasheng on my cargo bike. It works well here but it will make too wide of a system for use in a front triangle I feel.

You can run the GX35 off axis no problem but it won't make it any narrower.