TourSleazy: 2.5HP Honda powered Tour Easy clone

Discussion in 'Photos & Bicycle Builds' started by weez, Feb 23, 2008.

  1. weez

    weez Member

    Hi all,

    I introduced myself over here, thought I'd take a bit of time and introduce you to my more-or-less continuous R&D powered bike project. This nuttiness has been going since about 2002.

    TourSleazy (TS) is so named because it is inspired by the TourEasy LWB layout but built mainly out of junk. It started life with solid suspension front and rear,

    but when my knees complained, TS sprouted a Honda G100, 97cc sidevalve engine. Riding the bike in its early human powered configuration dictated that rear suspension was necessary to cope with marginal roads at high speeds (for a bicycle, that is). I cut up a junked MTB with a cantilever rear suspension and grafted that into TS's frame.

    There's numerous ways to transmit drive to the rear wheel on a motorised bike, some better than others. Tyre friction drives are the least desirable because of tyre wear and drive wheel slippage when there is moisture or other contaminants on the tyre tread surface. Drive sprockets clamped to wheel spokes IMNSFHO are downright unsafe, though I'm quite aware that a number of kits use this method. Spoke breakage looks like too real a possibility for my tastes.

    While it would be much more mechanically complex than other means, I concluded that the safest, most durable and efficient way to transmit drive to the rear wheel was via the existing chain and sprockets. This would also facilitate the use of the derailleur's wide range of ratios with engine drive. Pedal and engine drive would both go via the single drive chain.

    Isolating the engine drive from the pedal drive (so pedals don't spin when the engine is driving the bike and the pedals don't unnecessarily spin the primary drive) and combining the drive forces turned into quite a bit of an engineering challenge for this non-engineer. I came up with a differential drive system which allows drive either from the engine, the pedals or both simultaneously, in any proportion. This is accomplished by way of a 5/8" shaft running in ball bearings which are fitted to the former BB shell in the rear suspension's cantilever.

    On the engine drive side of the shaft is a BMX-type freewheel, fitted via a custom machined adapter (33mm fine thread to 5/8" keyed shaft). There's an 84T (bout 10" dia) sprocket for #35 chain bolted between the teeth of the sprocket on the engine drive side- a chain runs from the 'dinner plate' sprocket to the centrif clutch on the engine. The LH side freewheel does not have to be modified to run 'left handed' as the shaft adapter allows use of an ordinary freewheel.

    On the other side of the shaft, there's two more freewheels mounted on another custom machined 33mm threaded->5/8" keyed shaft adapter. A 5-speed rear wheel cluster fitted to the outside end of the shaft isolates the shaft's rotation from the pedal drive. If the engine is not running, pedal drive spins the jackshaft but the freewheel on the 'dinner plate' prevents the engine's primary drive and clutch driven cup from being spun.

    Another BMX freewheel with an 18T sprocket suiting derailleur chain, is used to transmit drive to the rear wheel. This one doesn't really need to be an operating freewheel, could be a sprocket simply fixed to the 33mm>5/8" shaft adapter. The freewheel action of the derailleur cluster in the rear wheel makes this drive freewheel redundant- it's just a convenient way to fit a sprocket to the 5/8" jackshaft.

    One of the biggest challenges in motorised bike construction is getting sufficient gear reduction in the engine driveline so the engine is running close to its torque peak when the bike is at ordinary bicycle road speeds (up to 50km/h). Small 2-cycle (ie weedwacker) and 4-cycle engines (ie GX31) operate at 7200rpm. Not only did I not want a tiny little engine on the bike screaming at high revs, I found that fitting sufficient gear reduction for an engine turning 7200rpm would take more than chains and sprockets, given the possibilities of readily available components and the size of existing sprocks on the centrif clutch and rear wheel. It would take a gear reduction box, heavy and expensive. So, I selected a slightly larger but slower spinning engine than most builders employ. I found a 2nd hand Honda G100, 4-stroke 97cc sidevalve motor which runs at 3600rpm and worked that into the design. Bonuses are that the Honda motor can sit for months unused yet start on the 1st or 2nd pull, every single time. The sidevalve (flathead) engine design favours high torque at relatively low RPM on the torque curve, meaning the engine works better running slower- and quieter.

    All well and good- until out on the road, of course!

    In practise, TS is great to ride, until one is tempted to run it as fast as it can go. At ordinary bike speeds (40km/h and under), the drive system behaves very well.

    However, when pushed to 55-60km/h in 7th gear, the final drive chain is on the smallest sprocket on the rear derailleur. This means that the chain is being held in tension only by the derailleur tensioner and is really quite floppy.

    This becomes a problem on rough roads, where the drive chain tends to jump off the driving sprocket on the jackshaft. I added a tensioner on the 'pull' side of the final drive chain, which aligns the chain before it gets to the driving sprocket. Works very well- but the plastic idler wheels on the tensioner get chewed up very quickly (about 200-300km per set of idler wheels).

    TS is torn down at this moment, clamped up in the workstand, getting a new front frame section to suit a suspension/disc brake front end, shown here in mockup.


    The driveline problem is going to be sorted while it's there. To eliminate the slacky drive chain, I was thinking about fitting a 3 to 7 speed internally geared rear hub, but Alaskavan brilliantly suggested the NuVinci CVT hub.


    I'm investigating both options, as they would eliminate the need for a chain tensioner in the final drive. I can also fit a larger sprocket to whatever size sprock is supplied on either the NuVinci or traditional internally geared hub, to slow the bike down a bit and improve hillclimbing abilty. I just need to do some research on exactly how much torque these hubs can be expected to handle. Hard info to come by as the makers of these hubs are not usually interested in supplying information for non-standard applications of their products.

    I also have a Comet 'Torq-A-Verter' TAV-30 belt-type torque converter sitting on the shelf, bought for another project, but it may have an application in TS's driveline. If I were to fit the TAV in TS's primary drive, replacing the centrif clutch but driving the existing 84T dinner-plate drive reduction sprocket on the jackshaft, it would add another 2:1 reduction multiplication (when the engine is running wide open- the TAV is 0.92:1, a bit of overdrive, at lower RPMs), increasing the primary driveline reduction to 14:1. 1st gear would then be about a 28:1 reduction with the engine on the 3600RPM governor, making for SERIOUSLY stump-pulling hillclimbing power, necessary for my new mountainous surrounds. I'd prefer to reserve the TAV for the other project, but we'll see where I wind up. :)

    Thanks for suffering through the long post, but I'm catching you up on the last 6 years. :)

    I'm happy to answer questions about TS but I'm happier yet to get good suggestions for improvements. :)
    Last edited: Feb 23, 2008


    RATRODER Guest

    weez, For a non-engineer you sure did some fine engineering. louis
  3. weez

    weez Member

    Thanks, Louis. :)

    If I had the driveline thing to do over again, I'd have heat-treated the 33mm-5/8" shaft adapters. I haven't tried to disassemble them, but I suspect they may never come apart. They were machined in rather soft steel and the fine 33mm threads, while there is full contact with the threads in the freewheels, have surely copped a bollocking, especially after snapping the final drive chain when it jumped the track a few times.

    If I had the whole thing to do over again, I might have made up a special rear hub suiting a LH drive sprocket (or used a disc brake hub) and powered it with a Honda Z50 or Chinese copy engine with an internal 4 speed gearbox. The bike driveline bits tend toward being a bit fragile in this application.
  4. wavygravy

    wavygravy Guest

    great work weez! im loveing that build!
  5. weez

    weez Member

    thanks wg. :)

    TS ran for 1085km per the bike computer odo before I had to pull it off the road to upgrade the front fork and consequentially, rebuild the front half of the frame. It's a big job and we've moved house in mid-project. The upside is my new workshop is about 4x larger. I can swing TWO cats in the new digs. :)

    97% of my motivation for posting this here is to kinda collect my thoughts about it and perhaps jump-start the rebuild... TS has been clamped up naked in the workstand for far too long with no progress. I also now live in a very touristy World Heritage listed national park area and I haven't got a bike on two wheels. Need to get with the program! :D
  6. This thread made my day.
    THANK YOU for sharing this.
    That bike is AWESOME!
  7. Scottm

    Scottm Guest

    I'm not sure I understand most of the techincal nfo(no need to repeat yourself) I'm still learning, but it is quite impressive. Have you patented it yet?
    Thanks for taking the time to put that excellent presentation together.
  8. weez

    weez Member

    LF, thanks for that. :)

    I gotta get a little AWESOME around my energy levels and finish the refit job. WAITER! MORE COFFEE! :lol:

    Thanks for the thanks. :)

    I've had build pix hanging around for years now, mainly for my own reference, never published them before. :)

    I don't think there's anything patentable in this... mmmm.... hmmm.... maybe. The differential drive may have some possibility of a patent on the basis of an innovation in the use of an already patented device, in terms of the use of ratcheting freewheels as kind of a mechanical diode, but I'd much rather share the design than profit from it. I'm sure someone else has already done this. Jim Gallant may have used something quite similar on his SWB/GX31 Honda.
  9. weez

    weez Member

    Now that I go back and look carefully at Jim G's mid-drive, we did things almost identically, but quite independently. Jim's motor-assist mod to his SWB was done in 2001. I built TS's powertrain in 2004, but I didn't find his website until after I'd been riding TS under power for a few months.

    Jim put a freewheel where I might have thought one redundant, on the motor's gearbox output shaft. Perhaps it was just an easy way to fit a sprocket there, as I did on my mid-drive output sprock.

    Jim recycled a wheel hub to carry his mid-drive and brazed it right where he wanted it (lucky so-and-so with an oxy rig...). Brazing is so much more forgiving than MIG & TIG (which I use at present) for bike frame building. You can build up pretty brass fillets that smooth out really easily, too. Grinding back a sloppy steel weld is a lot more work. It's much easier to deform or punch through a tube with a welder, too. If you really bollocks it up, you can even melt out old brazing and start over using the same steel tubes- nearly impossible with welding. I gotta get an oxy rig one day.
  10. Alaskavan

    Alaskavan Guest

    Good post Weez. When/if I ever get back to working on 2-wheelers, I may well use some of your ideas. Thanks.
  11. weez

    weez Member

    Thanks, Alaskavan. Your pointer on the NuVinci was brilliant, thanks for that.

    Picked up a really good tip about making sure the dropouts can deal with the torque reaction from the axle in another thread on here. If I go the NuVinci route, I'll fab up some meaty dropouts from a couple chunks of 3/8" plate (if there's enough axle length) and perhaps work in some motorcycle-like chain tensioner saddles with square holes suiting the flats on the NuVinci axle shaft. If the NuVinci can prise that apart... well... MORE STEEL! :D
    Last edited: Feb 24, 2008
  12. Hive

    Hive Guest


    So many projects on this site sparkle with the shine of sheer innovative genius and persistence; this bike included.

    I understand how much fun it is to craft something unique and that functions. It is like building a boat or car from scratch or even from careful planning that you have done yourself.

    The first time I did this, it was with a 26 foot wooden sailboat that turned out to have dry rot at the keel frames. By the following spring, a slick glass-covered racer slipped out of my garage (bow and stern tuck out front and rear of garage) and was flying around the lake. Necessity mothers invention. It is same with these projects.

    You guys amaze, with the welding, brazing, and ingenuity to turn out machines that turn heads - and make your cheeks tighten with pride.

    I used to think I was doing okie-dokie with my easy-go GEBE rigs that required some patient and well planned, smart cobbling to overcome unforeseen roadblocks, without messing up the project or adding more work, but you boys are on a different, much higher plane.

    I have gone from powered coaster, to bent - too hard to get going and dangerous in city for me - to semi crank forward. I am learning all the way, but never dreamed of making gears, cranks, fuel cells (gas tanks) and such, not to mention, the jigs needed to do such work, the good beer and the fun the neighbors have. (Neighbor built a plane in his garage...that was fun for us to watch and amazing also.) Making a lowly plumbing-pipe exhaust is a big deal for me.

    My hats are off to you, while I stick with simple stuff.
    Last edited by a moderator: Feb 25, 2008
  13. weez

    weez Member

    Thanks for the praise! :)

    Pride doesn't make my cheeks tighten... but a brake cable inadvertently left disconnected before a test ride has most certainly had that effect on me in the past. :grin:
  14. Hive

    Hive Guest

    No Doubt

    That'd do it alright!

    Bad feeling and the tightening increases as the speed shortens the distance to be traveled...probably as the speed increases the tightening squared.

    Coincidentally, my (first) helmet arrived today.
  15. Dean

    Dean Member

    :grin: ROTFLMAO!!! :grin:
    That was classic!
    Yeah, I guess that would make anyone's cheeks tighten up just a little.
    Hopefully, there weren't any old ladies crossing your path at that time.

    Anyway, welcome to the forum and a couple of comments on your well written and well formatted post.

    You say that in high gear, the deurailer is stuck out so far that it has a tendency to flop around, allowing the chain to come off at higher speeds.
    What if you were to pull a link or two out of that chain?
    That would "tighten up" the derailer in the higher gears. Might not flop around so much.
    The down side(s) may be, harder to shift or unable to shift into certain gears, due to lack of chain length.

    You also mentioned that you installed a tensioner on the power chain side (between the engine and that "dinner plate"), but you're having trouble with plastic wheels on the tensioner wearing away.
    What if it were replaced with another deurailer tensioner?
    That one uses a metal sprocket that would last longer.
    Replace the plastic wheel on the current tensioner with the metal sprocket from an old deurailer tensioner?
    Should solve that problem, if you can make them fit (and somehow, I think you could).

    Good luck with your project. Interesting read.

    Last edited: Mar 14, 2008
  16. weez

    weez Member

    You know, at that moment, I was rather hoping for an old lady or two in the path... anything to soften the impending crash. :lol:
    Thanks. :)

    In top gear in a derailleur, the chain is on the smallest sprocket. If there's enough chain to go around the (largest) 1st gear sprocket and the driving sprocket, obviously there will be a lot of excess chain length when shifted to 7th. The tensioner/s are responsible for taking up that slack in top gear. If I shortened the chain to make it taut in 7th, it would not be difficult to shift into anything below 7th- it would be impossible.

    Not quite. TS has a primary chain drive on the left side of the bike, running from the centrif clutch on the engine, back to the 84T 'dinner plate' sprocket. There's no tensioner in the primary. The engine mount can be slipped forward and back to set the tension in the primary drive chain.

    The derailleur tensioners are in TS's final drive chain, which runs on the right-hand side of the bike, from the jackshaft to the rear wheel; one in the typical position below the cluster, which is connected to a shifter cable, another in the final drive on the 'pull' (upper) side of the chain run, which aligns the chain as it feeds onto the driving sprocket on the jackshaft/mid drive.


    That would be OK if the tensioners had enough spring pressure to reliably hold the final drive chain in tension in top gear at 60km/h while running over rough surfaces. Unfortunately, they don't- and when the chain jumps off, it often gets caught and breaks the final drive chain, destroying the tensioner. Just not enough strength in those tensioners' springs and no room in them to add a stronger spring. Plastic wheels run fine until they wear out, but I more frequently see derailleur tensioners completely destroyed by a snapped chain, long before the idler wheels wear out.

    Soon as I can lay my hands on a NuVinci, I think the problem will go away as the final drive chain will not need any tensioners. I'll have to cook up new dropouts for the swingarm which will allow the rear wheel to move back and forth to tension the chain once the NuVinci goes in, but the chain will be taut and unable to jump off just because the bike is on a rough road.

    Thanks again for that, Dean. It's a good bit of fun. Will post more about it when I find the dough for a NuVinci and some tubing for my new front frame section.
    Last edited: Mar 14, 2008
  17. BSA

    BSA Guest

    Neat, that's so cool.

  18. Dean

    Dean Member


    Do you feel removing, say, one link from the chain would make it impossible to shift into any other gear other than 7th?

  19. weez

    weez Member

    There's an absolute minimum chain length in a derailleur; that is the distance around the 1st (largest) gear cog and the driving sprocket. If the chain is taut around 1st gear, yes- removing even just one link (though you functionally would have to remove at least 2 to remove any at all) would prevent shifting into 1st.


    I already had the chain as short as it could possibly be.

    If the chain were taut in 7th, it'd never shift into 6th or below.
    Last edited: Mar 15, 2008
  20. Dean

    Dean Member

    Aaaahhhhhhhh, now I see.
    My apologies if you mentioned the part of your quote I underlined, earlier.
    That is the first I've noticed it being mentioned.