FD Roller, Material?, Method?

Discussion in 'Motorized Bicycle General Discussion' started by Nehmo, Jan 1, 2013.

  1. Nehmo

    Nehmo Member

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    Has there been any general agreement on the best material & method to make a friction drive (FD) roller?
    I see that cannonball2 seemed to settle on wood, but he didn't say that exactly.

    Some people have suggested getting sheet rubber via eBay

    The Roller, what is the latest opinion on the subject?

    And while we're on the subject, what's the wisdom on fixing the roller to the shaft?
     
  2. Nehmo

    Nehmo Member

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    I'm replying to my own post because I felt sorry for the original post being so lonely sitting by himself.
    I did try making a roller from the rubber base of a pylon. It lasted about 6 miles (10 km). The stuff is composed of recycled pieces of rubber, probably from tires.
    [​IMG]
     
  3. cannonball2

    cannonball2 Active Member

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    Oak is where its at fellas.
     
  4. Nehmo

    Nehmo Member

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    Are you currently regularly riding a bike that uses an oak roller? And there is a hiatus in your posting history. What were you doing?
    Your roller system uses a shaft with a threaded hole > that holds a bolt > that squeezes the bearing center > that works through some washers > that squeezes the roller.
    [​IMG] This pic was in another thread.
    I don't have a threaded shaft, and I'm not set up to make one.

    I have a 0.5" shaft with a hole going across a diameter. A pin is in the hole. Hockey pucks are on both sides of the pin. Bolts and nuts sandwich the pucks around the pin.

    I would like a larger roller. I'm thinking 4", but I can't find any sheet rubber locally. (But I'm sure they are in this city somewhere.)

    Tractor Supply has a stall mat. It's 0.75 inch thick. Is that what you use when you used rubber? I can't find any sheets of rubber locally.
     
  5. cannonball2

    cannonball2 Active Member

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    I have been going through lifes wringer in the last year. The death of 2 parents, a divorce, and a re-location to coastal Ga. from the Atlanta area.
    That said Im in a much more MB friendly area and brought 4 with me, I still have the original FD MB that has the most miles ridden, something close to 3k. None have been riden in the last 6mos. Time to get them going!
    I orginally used the TSC stall mats for my rollers. The last mat I bought was of a different compound and was not suitable, failed quickly. That prompted the move to wood. Oak wears like iron, doesnt matter what you ride on. Pretty easy on the tire too.
    That said it is only suited for larger slower turning rollers 2" up. Fir 2x4s work well also for experimentation(heck I have run some permanently) the largest I have run is 3.25 I believe. If you want a 4" laminate cuts from an oak cutting board.
    Thats basically my set up in your diagrahm, You could get the same results with threaded rod and nuts I guess.
    Dont know what you are running but you will have a pretty good pedal off speed to smoothly get going with a 4". Will have a heck of a top end, probably up in the 40s+. Hills will be your real enemy. My ungoverned Lifan 99cc topped 40 with the 3.25 around 4500rpm. Climbed all but the bigger hills ok.
     
  6. Nehmo

    Nehmo Member

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    Sometimes you're the shirt, and sometimes you're the wringer.

    A new location means a fresh start. And coastal Georgia? Geographically, I can't find any sympathy. That's prime space. What city, specifically, did you honor by your habitation?
     
  7. Nehmo

    Nehmo Member

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    The roads in Kansas City are not sufficiently smooth to accommodate a bike (front spring & hard tail) suspension going 40 mph (64 km/hr), and I'm happy to do 30.
    I realize many of you use a stiff fork on the front. I don't see how you do it.
    [​IMG]
     
    #7 Nehmo, Jan 10, 2013
    Last edited: Jan 10, 2013
  8. cannonball2

    cannonball2 Active Member

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    Im in Brunswick with a very nice house on the salt marshes/river. 10/15min from St Simons and Jekyll iIsland. Perfect area for my MB amd M/C riding.
    Is that a Preddy on your bike? If so why thoughts on a 4" roller? A 3" @ 4000rpm will get you 35 tops, means a leisurely cruise around 30 in the upper 3 thou range. I have different sizes for differet situations. If I were to say ride around town here I would use a roller around 2" for great stop and go. If I wanted to cruise up the coast I would use a roller closer to 3" to cover distances better. A direct drive trans(like mine) requires compromises in ratios, or patience with a lower more tractable ratio if you only have one. You showed my jackshaft set up is that what you are going to use, your bike looks direct drive.
     
  9. Nehmo

    Nehmo Member

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    I want a larger roller because that will give a larger contact area between the roller and tire. The roller in my case is on a shaft driven by a sheave. I can adjust the ratio by changing the sheave sizes.
    My engine is a 79cc Predator,
    That's not my drawing. It was in another thread on the subject in which you contributed.
     
  10. Nehmo

    Nehmo Member

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    [​IMG]
    This is the most recent pic.
    It now runs acceptably, but I've learned a lot of things during this bike's evolution, and I'm conflicted in which direction to go. Should I start over with a new design, or should I just improve this as far as I can go?
     
  11. cannonball2

    cannonball2 Active Member

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    I guess thats a question only you can answer. What needs improving? What issues are you having? FDs have a lot of advantages as well as some disadvantages. Depends on what you are after in an MB I guess. I like the simplicity of my direct drive, its about as close to 100% reliability as it gets, that counts a lot when far from home, I still have 2 chain drive MBs as well.
     
  12. Nehmo

    Nehmo Member

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    There are several issues, or things needing improvement. And I could work on them, but now I'm disenchanted in the basic design of my motor-mounting arrangement. So, I'm considering starting over.

    I chose the arrangement of having the roller & motor on a frame together because it would move as one unit, and thus the motor-to-roller-shaft belt wouldn't need to grow or shrink as the roller changed position. I also though the weight of the motor (tending to engage the clutch) would be advantageous.
    I now can envision better arrangements because my experience with this arrangement has given me a better idea of what's needed.

    Ideally, I'd have the motor in a fixed (but spring-shock-suspended with the rider) position and have an easy to control clutch that positively engages & positively disengages.

    Anyway, regarding the current build, I made 2 oak wood rollers and I'll mount them on their shaft tonight.

    It would have been nice to use a lathe, but I used a circle cutter because it was cheap. [​IMG]

    I used 3/4" (actual) (2cm) thick oak board to make 3.25" (8cm) diameter disks. I'll sandwich them around the pin going through the shaft to fix them.

    There sure are a lot of different kinds of circle cutters.
     
    #12 Nehmo, Jan 18, 2013
    Last edited: Jan 18, 2013
  13. cannonball2

    cannonball2 Active Member

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    The hole saws cut a pretty true roller as cut. If the pilot hole left by the saw is drilled @ 90 degrees it a decent running roller. I have since the move sold my lathe, but I used to true them on it. Surprisingly it required very little material removed to do it. I understand the reasoning behind the belt driven roller, I have built several. But the simplest, best operating, most user friendly FD I have is the direct drive Lifan/Mongoose full suspension MTB. Ratio changes are less than a minute, and it has enough bite to kill the engine with the brakes at lower speeds. I do have some spring down tension to assist with the engine weight. Mine is mounted entirely in the rear suspension so there is no interaction.
     
  14. Nehmo

    Nehmo Member

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    [​IMG]
    It sure is counter-intuitive to use wood for a mechanical element that's going to see abrasion.
    [​IMG]
    But wooden wagon wheels were once the norm, so there's plenty of experience of this kind of use.
    Maybe the roller should be completely wear-free when contrasted with the tire. The roller gets about 10 times the contact time as the tire by size, so if it were the same material as the tire, it would wear in diameter at a rate 10 times that of the tire.
    Considering this relative rate of duty, to compensate, the roller should be composed of material much more wear-resistant than the tire. :confused:
    I suppose that means metal, perhaps aluminum?
     
  15. cannonball2

    cannonball2 Active Member

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    Trust me the roller basically doesnt wear. They actually get a kind of polished finish. I seal them in and out with polyurethane in case I get caught in the wet The tires run around 1500 miles. I run the standard 2.125 cruiser tire, Ive tried a lot of different types and these wear well, are common and relatively cheap. I run 30lbs pressure for ride quality and the roller settles in to the tire better. The 1.95 and smaller tires are harder to get as good a bite on. I had a knurled metal roller and was supprised how fast the knurls rounded off. Good down force is a must other wise tire wear is higher due to slippage. The weight (22lbs) of my Lifan was not enough. I will try to post a pic in the next few days of the roller with over 2k miles on it.
     
  16. Nehmo

    Nehmo Member

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    Something a bit disheartening happened. One of the 3 oak disks split along a grain just by the assembling process. I'll make another, and yes, I realize wood is unpredictable when it comes to strength along the grain lines.
    I now think aluminum would be the best material. If I can get some thick sheet Al, I'll laminate them into a roller.
    As long as the friction is sufficient to give the tire the ability to kill the engine by breaking, then it doesn't matter how abrasive the roller is to the tire.
     
  17. cannonball2

    cannonball2 Active Member

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    Better late than never, here are the pics of the roller with 2k plus miles as well as my rain roller. The 2.1" was made from 2 laminations of a discarded 1" oak cutting board. Was actually laminated on the engines crankshaft with gorilla glue(grease the crank, ask me how I know!). It still bacically mics as unworn. The second roller is jut a simple one piece hole sawing of a fir 2x4, hence the larger rubber cush drive piece. This thing will positively drive even through standing water, though it is for emergency caught in the rain/gotta get home use. Not tire friendly, not bad when wet, but change it out quick when dry! On this bike I have rollers in the carry bag from 1.8-2.4. The 1.8-1.9 are hilly/ trailer pull rollers, while the 2.1-2.4 are cruise rollers. All change in less than a minute.
     

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  18. Nehmo

    Nehmo Member

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    My oak roller is installed and functioning. It's working acceptably. I'm having some slipping, but I haven't had a dry day yet, so I expect that to improve.

    In your case, cannonball2, the roller is limited in size because your only gearing is that of the roller-to-tire. Since I'm using an intermediate shaft, I can size the roller larger, and then I can adjust the ratio by pulley sizes.

    I also attach the roller to the shaft by a different method. I sandwich a pin going through the shaft.

    My next experiment will be using 2 4"to6" diameter aluminum cups (or something).
     

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