It Kind Of Boggles The Mind When You Really Think About It

The motorcycle chain.

A bunch of really small, hardened metal parts, all connected together to transmit horse power from an engine/transmission combination to a wheel at a determined remote point to give it motive force and make it spin.




VERY, small parts that can transmit incredible amounts of torque at unimaginable speed.

Like this,

How all those little parts don’t just explode in a nightmare of high speed shrapnel is nothing short of amazing.

7 thoughts on “It Kind Of Boggles The Mind When You Really Think About It

  1. And not one mooslime was involved in the engineering…..I’m on a rant today. Mooslimes telling me that they developed _______(fill in the blank). Gawd awful group of people!
    Sorry about the burst of spittle……just had to get that off my chest.
    You may go back to your regularly scheduled broadcast.



  2. You ain’t kidding chains for motorcycles are a complex device. They went thru a big evolution about 1996-98.
    Always understood chains and belts like a Gilmer belt are very efficient methods of power transfer.
    I know from racing motorcycles, as you say Phil, its amazing they don’t come apart, until they came out with the “O Ring” type chains, they did fail quite frequently and right at the worst time. A constant concern for us racers. With the advent of the O-Ring types, failure just about dropped to zero, and if your chain failed, it was guaranteed you where an idiot who couldn’t be bothered with lubing it.
    Basically it seems to me, the way the chain runs over and around your sprockets, it wants to fling everything off it. Talking serious G forces. The O-Ring design kept lubrication where it mattered most, between the pin and roller. They also began to “Quad Stake” the pins to the plates, I think this helped a shitload with side flex wear as the chain whips under acceleration or decel.
    On a motorcycle you need some slack, because the pivot point of the swing arm as it travels through its arc under suspension movement, the chain experiences more slack or gets tighter. The pivot point is fixed, and is to the rear of the drive sprocket center. Also the pivot point benefits much from being placed a little bit above the drive center, this reduces whats called “squat” when you accelerate, which has a negative effect on steering geometry as it lessens the steering head angle, right at the worst time when you are coming out of a corner rolling the gas on, decreasing the bikes ability to steer quicker.
    This is also one of those faustian bargains, where just a bit too much is not good, and a tiny bit too tight is really bad. The last stretches the shit out of a chain, wears your sprockets quicker, and puts a huge load on the drive sprocket bearing.
    The O-Ring chains also came pre stretched, a nice feature, as with the non O-Ring chains would stretch like made as they “bedded in”, then where god for a race, then they would stretch like mad till they come apart.
    You make nice to a top line O-Ring chain, be real careful keeping it adjusted just right and well lubed they could last you an entire race season and enough left over to run on a street bike or as a spare. I think when they went O-Ring, the manufacturers went the whole nine yards and improved the use of steel alloys and heat treating also. They aren’t cheap. The real fine race chains cost you upwards $200+, but they are still cheap for what you get.

    I think the advent of the radial bike tire, O-Ring chains, affordable cast iron front brake rotors and light weight magnesium alloy cast wheels, along with the invention of “upside down” front fork tubes, had revolutionary effects on bike racing, they all came about pretty much within the same time frame.

    O-Ring chains also freed up considerable power right where it counted, at the rear wheel. We would see as much as 15hp once the chain warmed up on the dyno. A worn chain eats power like there’s no tomorrow. You could actually feel an improvement putting on an O-Ring chain.
    Its an aside, but its those little things that add up in racing. The Ceramic type ball bearing, when used on motorcycles, at high speeds over 100mph, freed up around 5 hp, and the “seal-less” type ball bearings, the ones with a steel dust shield, which clears the inner race by about a couple tenths of a thousandths of an inch, .0001, also freed up around 5hp just by eliminating the drag from the tiny contact the seal had with the inner race.


  3. Notice that the chain was tight when he first started, then notice the chain slop when the frame and suspension were undergoing stress. That’s because of the torque introduced to the frame and the twisting of the suspension loosen things up a bit…

    *I* wouldn’t do it, I would prefer either a toothed-belt drive (which have a tendency to strip and break) or driveshaft bike. The guy’s got guts, for sure, because that chain going *blooey* at high torque/speed is kinda detrimental to the left side of your extremities……


    • Drive shafts bike in racing have a terrible reputation to highside if your violently letting off or on the fuel in or out of a corner leaned over. Lot of street guys discovered that on the Yamaha Virago’s. Great power, but they bite with the poorly designed driveshaft geometry to keep the ride height low and comfy. I raced a Beemer a couple times, the torque effects from the driveshaft transmit right to the chassis where the chain drive is a lot more subtle. Raced a Buell with the factory belt drive for a bit till changing to chain drive, the belt drive has a tendency to steer well on left turns and turn hard on righties. I think because the belt is quite stiff in one axis, they don’t like to flex in 3 axis’s, at least in relative terms to the chassis, where the factory frame is rubber mounted to the engine.
      I built a Titanium chassis for it, and used hard durometer polyurethane isolator bushings in mounting bolt cups, gave a little bit of isolation/suspension, those 45 degree twins don’t have primary balance, and with the huge aircraft rotary engine/slave pin rod flywheel, they have a few frequency points they go in and out of, the mounts kept the vibration from cracking the frame, made a longer swing arm, that worked very well for me with jacking at the pivot point. A custom Pensky shock with unlimited hi & lo speed compression/rebound dampening adjustment, and a Titanium spring, plus those nifty hydraulic spring perches, and increasing the rate by going with a straight cantilever shock mounting, alleviated most of those forces you mention under suspension loading.
      Neat thing about the Buell engines, they make huge torque, so running the largest primary sprocket will fit, and final gearing for grunt, you stay way down below red line, that makes them smoother.
      The Beemers and have awesome grunt too, perfect primary balance, if you could convert to chain drive they would be serious super twins race bikes. Out of the apex they pull like stink. The Ducati’s with their 90 degree V balance and close firing order have a “gentle” power pulse, lot of relative pause between power strokes, makes them very controllable. The stressed member engine/engine swing arm pivot mount is forgiving too. The SV 650’s are a little better. Nice compact, light weight V engine, less torque but excellent linear, higher relative hp, they go very well. Typical of a good pent roof 4 valve head, nice smooth predictable midrange power.
      The Buell engine is a lot of fun though. With that monster grunt they deliver, you can short shift and really get some serious out of the apex acceleration with them. On short and technical tracks they are hard to beat once you get the factory weight off them. The engines are heavy. The big clutch is a second big gyro, produces some interesting character.
      Everything is a balance of compromises.


  4. Dad was a motorcycle guy back in the late 1930’s. He and my uncle rode Vincents then BSA. Old trick he mentioned was to take the chain off, clean with in kerosene, then dump it into a tin can full of grease which was carefully boiled on a campfire (to avoid burning down the house). Once good hot and liquid, the can was taken off the heat and allowed to cool back into a paste. The chain was then hooked out, wiped down with a rag and installed on the bike. Early chains stretched quite a bit in use, they were constantly having to readjust the wheel to keep tension correct. Sadly (and quite smartly) he dumped the bike not long after I was born (mother may have had a role in that) as either he would have killed himself or I would likely have by riding as a teen. Damn near killed myself on a standard bicycle having an argument with a Citroen, so it was highly probable.


  5. If one looks at the “permissible power” chart from chain manufacturers one instantly realizes there’s not a chain drive in existence that does not exceed, often by multiple orders of magnitude, manufacturers’ power limits.

    Way before O-ring chains we used standard #35 chain in kart racing. On sprint karts the wise person lubed between heats and chains still lasted almost half a season. On enduro karts we installed gravity drip oilers (and rightly earned the hatred of every other motor racing group that used the track afterward – in 1968 the Winternationals at VIR drew >800 entries across a dozen classes, each of which – back then – had at last one chain (dual engine karts had two) that was allowed to consume 1 pint of oil per chain during the 1-hour race. Which did not include any of the practice time.) The gravity oilers had 1/4″ clear tubing cut at about 60 degrees and held not quite touching the driven sprocket just inside the chain. That way the rotating sprocket surface would pull oil from the tube end and centrifugal force would throw it through the chain. A very few – the anal retentive and OCD set – would build their oilers to feed both sides of the sprocket, everyone else just oiled one side of the chain.

    Anyway, until Gilmer belts came along, or (the very few and quite rare) of us who went with Margay gearboxes, most enduro racers went through 2 chains per engine per race weekend, one for practice, one for the race. Some of us did what Terrapod’s dad did – I used a boiling 50/50 mixture of 40W oil and molybdenum sulfide (back then it was sold as SLIP brand oil treatment…) but new chains had to be soaked and scrubbed in Varsol then TCE first to get the thick factory grease out of them. The “best” chains were fully degreased, lightly oiled with 30W, then track-used for about 10 minutes to get them past the intitial stretch period then cleaned again and oil-boiled. For my enduro rig’s drip oiler I mixed 1 gal of 90W hypoid mixed with 1 pt of STP and 8 oz of moly; thick enough to almost exactly consume 1pt/hr, sticky/gummy enough to stick to the chain. And everything else on the back of the kart. (A note on Margay boxes – single speed, expensive gear changes – each change had 2 needle bearing blocks and the internally splined change gear, and the box was about 15X the weight of chain, 2 sprockets and the axle sprocket hub, and the GB was a LOT more expensive. The advantages were a sealed unit, gears and bearing ran in ATF, no issues with sprocket-to-sprocket alignment, no flexing in use (any engine movement destroyed the connections on exhaust expansion chambers), it made oil-bath slip centrifugal clutches easier (Margay made their own vented oil bath clutch housing which was also the engine-to-GB mount), and nothing inside dried out during a race and consumed more horsepower or broke). Margay made a dual-engine box, but the RH engine had to be mounted upside down so the duals usually went with 2 boxes, doubling the expenses.

    As soon as Gilmer belt technology got sized and priced to fit karts everyone went to it overnight. Great stuff.


  6. My last gig in the industrial trades had me oiling 4″ wide conveyor chains about
    once a week. The things looked like a super-sized motorcycle or bicycle chains.
    For years the mill geezer who did the job before me would pull the guards and
    squirt the links with an oil can. I said screw that, I got a pail and a 4″ paint brush.
    It worked out well until some idiot at another mill got the bright idea to yank a
    piece of baling wire out of a link right next to the sprocket. He is now known
    as “Lefty.”

    This caused the idiots in management to overreact. I was told I could no longer
    remove the guards to do the job. Some Wyle E. Coyote “Super Genius” type
    came up with a new way of doing the job, a pump type pesticide sprayer. Even
    a lightweight oil does not spray for shit using one of these things. I had to leave
    the expanded metal mesh guards and hit the individual links at the pins. Now,
    instead of getting an overview of the link condition I had to so narrow my focus
    that I could not see the big picture.

    The thing took an epic dump and of course, it was my fault. Years earlier, I
    suggested solenoid operated gravity feed oilers which have been around since
    the mid 19th century. Every time the conveyor motor started the links would be
    oiled automatically. As for gauging the condition of the links, plexiglass instead
    of the expanded metal guards. Too rational a concept for paper mill managers
    to comprehend!


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