Sprockets & Torque & Cruising Speed & MPG & Chains

Discussion in 'Motorbike Technical Discussion' started by Bill Miller., Aug 18, 2008.

  1. Bill Miller.

    Bill Miller. Guest

    I could use a brief refresher course on changing sprockets on a
    motorcycle. With a dual purpose bike I once had, when going off-road,
    I simply lengthened the chain and hung it around a larger rear
    sprocket. Guess I had a "dual" sprocket on the back of that bike.

    On the TW200 I thinking of buying, I understand it comes with a stock
    14 front sprocket and a stock 50 or 52 rear. And since I've clearly
    stated many times that its use will primarily be ON-ROAD, I intend to
    switch out the tires to the TW203 and TW204 plus perhaps some sprocket

    1--What will be the performance results of changing the front to a 15
    or even a 12?

    2--What will be the performance results of changing the rear to a 47
    or a 42 or even a 55?

    3--By performance results I mean mpg, shift points, higher speed and
    quieter engine operation, etc.

    4--Is there a publication and/or online source that would provide in-
    depth info into sprocket modifications on motorcycles?



    PS--When ordering an aftermarket sprocket, do you need to order a new
    chain with it?
    Bill Miller., Aug 18, 2008
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  2. Bill Miller.

    TOG@Toil Guest

    For Christ's sake, leave it as standard. It's got sod all power
    anyway, really, and gearing it up will be a waste of time on-road, and
    gearing it down will make it snappier on-road (and more useful off-
    road) but thirstier.

    Your proposed gearing changes on the front sprocket are daft: I doubt
    whether it's really got the power to pull top gear with a 15T
    sprocket, and 12 is way too low, plus it'll wear out the sprocket
    really fast.

    Your rear sprocket changes are even dafter. A 42-tooth rear sprocket
    with a 14-tooth standard front will give a gearing of exactly 3:1, and
    no way on God's earth will it pull it. Think - what happens when you
    go up a hill in a car, on a bicycle, or anything in a high gear? It
    slows down. Why should a motorcycle be any different?

    If a TW200 manages to pull, say, 75mph on the flat on stock gearing,
    then worst case (your biggest sprocket on the front and smallest on
    the rear) will gear it up to do 100mph or something (I can't be arsed
    to work out the calculations right now). *It won't pull it*.

    Effect on mpg is likely to be poor whatever you do: gearing it down
    means it'll be revving higher: gearing it up (unless it's geared
    abnormally low in the first place) won't improve things as you'll be
    holding the throttle wider open to get the poor thing to pull.

    As for whether you need a new chain: well, if you add or subtract
    sprocket teeth, it doesn't take rocket science to work out what will
    happen to the length of the chain run.

    Jesus, just leave it alone. Ride it first, and then decide whether the
    gearing needs to be fucked about with. Generally, however, you'll find
    that the manufacturer knows much better than you do. Do you really,
    really think that Mr Yamaha will get the gearing out by as much as 25%?

    [1] seat-of-pants figure taking your most wild sprocket extremes
    TOG@Toil, Aug 18, 2008
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  3. Bill Miller.

    . Guest

    All the gear ratios and tires sizes for the TW200 are available
    online. Look 'em up and plug them into this calculator.

    It's best to run new chain on new sprockets.

    We discussed the subject of re-gearing the TW200 extensively about a
    year ago with a guy who wanted to believe what he wanted to believe,
    that he would get phenomenal mileage without performance degradation.

    He's still around, with a name change, claiming that installing a
    smaller rear sprocket gives him better mileage and that he doesn't
    have to downshift for every little hill or headwind...

    But, if you study the TW200's gear ratios, you will see that they are
    not all equally spaced, they get closer and closer together as you
    shift up.

    This indicates that the TW200 really doesn't have a lot of surplus
    power to allow
    gearing it up very much.

    I wouldn't recommended raising the overall gearing more than about 3%
    or 4% if you don't want to spend a lot of time riding one gear lower
    than high gear.
    ., Aug 18, 2008
  4. Bill Miller.

    TOG@Toil Guest

    Now *there's* a useful link.
    Um, that's not the real point. The point is that by messing with the
    sprockets he's altering the chain run length.

    TOG@Toil, Aug 18, 2008
  5. Bill Miller.

    Bill Miller. Guest

    chain with it?

    I already realized a different sprocket would require a different
    chain length. On my old trail bike I use to add a small section of
    chain when changing to the larger off-road sprocket and pop it out
    when reverting back. My question was more of a "understood" comment
    sorta like it's a good idea to change the oil filter when you change
    the oil or both wiper blades when one goes bad. With any project,
    it's always best to have all the components start out equally new.

    Bill Miller., Aug 19, 2008
  6. Bill Miller.

    TOG@Toil Guest

    Jesus. Not one master link in a chain, but *two*.

    Look, it's a shit idea, so forget it.
    TOG@Toil, Aug 19, 2008
  7. We've been through all that in another thread. This bod wants to buy a
    TW, and then, basically, **** it up.
    The Older Gentleman, Aug 19, 2008
  8. OK. Carry on, that man.
    The Older Gentleman, Aug 20, 2008
  9. Bill Miller.

    Bill Miller. Guest

    One problem with that. I don''t want an XT225 and last time I checked,
    anyone, with his own fucking money, can buy any fucking motorcycle he
    wants and have it modified any fucking way he wants. Is that concept
    too deep for some of you old fuckers who can't stand change or someone
    having a different opinion than yours?
    TW, and then, basically, **** it up.

    No, you pompous bag of hot air with the personality quotient of a
    dried dog turd, not **** it up, simply modify to my liking. Yasee,
    you old shithead, lots of guys modify motorcycles, scooters, etc.. At
    least guys younger than 125, which would obviously leave you out of
    the mix. Gawd, you are one funny and weird old fucker. You don't
    have a clue about 2008, you're still locked in some 60's time warp or

    Any other fucking questions from you mindless fuckheads?

    Bill Miller., Aug 20, 2008
  10. Bill Miller.

    Bill Miller. Guest

    over Uncle Jay's computer.

    Your little so-called "baiting" routine doesn't work. You and the
    dumbass TOG just make me laugh with your silliness and stupidity about
    the real world.

    (Who appreciates all of the little silly-ass comebacks from the silly-
    ass group including silly-ass TOG and silly-ass Geyser. Thank you
    boys, keep those silly-ass comments coming. They're a riot. All of
    us here get a chuckle reading the responses from the OFC (Old
    Fuckheads Club).

    Bill Miller., Aug 20, 2008
  11. Bill Miller.

    TOG@Toil Guest

    I dunno. It seems to be working fine, from where I sit. :)
    TOG@Toil, Aug 20, 2008
  12. Bill Miller.

    TOG@Toil Guest

    By raising the gearing by 20% or more? That's not modifying: that's
    really fucking it up.f

    Ah, right, rattle in orbit again. Excellent.
    TOG@Toil, Aug 20, 2008
  13. Bill Miller.

    Bill Miller. Guest

    And, as usual, from where you sit, most everything is wrong.
    Especially since you spend most of your time sitting on your brain.
    You said it all TOG BUTT with your first two words "I dunno." And you
    probably haven't known shit since the day you were born. HAWHAWHAW


    (Still enjoying lots of laughter as I observe the old fools who
    continue to come back and dance for me. Who's baiting who TOG BUTT??
    HAHAHA YOU are the dipwads getting baited in these exchanges but
    you're too fucking stupid to realize it).
    Bill Miller., Aug 20, 2008
  14. Bill Miller.

    Bill Miller. Guest

    Not all all. Guess what TOG BUTT, despite how this fact will no doubt
    crush your fragile and inflated ego, the truth is "You don't know
    everything and you are dead ass wrong in your latest assumption." I
    have talked with a couple of techs and told them some of the brainless
    statements you've come up with and their usual response is "What is
    the guy, a dumb-assed newbie in the cycle world?"

    Basically, buttbrain, you're done. Your advice sucks, your brain has
    quit functioning, your attitude sucks and you also probably put on
    your pink dress, the one you were wearing in that photo, and suck
    anything that walks by. You're pitiful old man. Just call Dr.
    Kevorkian and be done with it. You're useless as dog piss on a clean
    carpet. LOLOLOL

    Bill Miller., Aug 20, 2008
  15. Bill Miller.

    Bill Miller. Guest

    So either learn to read the gist of an OP before you answer or people
    will think your name fits you perfectly, since a "geyser" is something
    that spews out a lot of hot steam, etc and in your case just spews out
    a lot of useless shit.

    The reason I quoted all of those sprocket sizes was those were the
    figures I got from others, they weren't my idea. You see, the purpose
    of the post was to get some help from the alleged "experts" on this
    group about choosing the right sprocket to meet the objective I had in
    mind---i.e. better mileage, quieter top speed operation, less shifting
    in the lower ranges, etc. IOW, making it more of a road bike than a
    trail bike. So what happens---the typical responses from the typical
    know-it-all fuckheads like that asshole TOG and a couple of others.

    They, and perhaps you, have no concept of how to actually help anyone,
    they only exist to spew forth their personal, mindless opinions and
    whether or not they have anything to do with the post seems to be

    It's what you find on many newsgroup, the pompous, egocentric
    dickheads who don't know shit so they try to hide it by just
    denigrating the OP and his ideas.

    So piss off, Geyser, and take TOG BUTT with you. Neither of you have
    anything valid to offer on this subject (or most of them on the
    newsgroup) anyway and you're just taking up bandwith with your
    bullshit. Besides, if you post again, it just provides more fodder
    for the good laughs we all get here from reading your crap. Leave the
    help to those who can actually provide it.


    Actually, I take that back...you and TOG ASS continue to respond.
    Laughing at you has become a regular recreational activity around
    here. HAHAHAHA
    Bill Miller., Aug 21, 2008
  16. Bill Miller.

    TOG@Toil Guest

    No, he doesn't, as he's not even got the bike yet, and the gearing
    variations he is proposing are, at their extrmes, totally impractical.

    Bike makers have whole departments dedicated to working out the
    gearing for thair machines. They don't *always* get it right: my own
    K1100LT is geared a bit too low in top, for a tourer, and my old
    Triumph 1200 Trophy was geared slightly too high. But by and large,
    correct gearing is more honoured in the observance than the breach[1].

    And he (or his 'expert' friends) is suggesting a possible combination
    of a 15-tooth front sprocket and a 42 rear (stock: 14/52). Or, at the
    low extreme, 12/55. There's no way the bike will pull the former and
    with the second, it'll be screaming its head off.

    If he wants to mess about with it, he should ride it, note down the
    rev/gear figures, see how many revs it's pulling flat out in top, and
    work from there. He might want to make a very small change, but until
    he rides the little whizzbang, there's little point in asking. And
    *no* point in asking about such daft sprocket sizes.

    [1] He'll have to look that inverted reference up.
    TOG@Toil, Aug 21, 2008
  17. To get these things you would likely want to add teeth in
    the rear sprocket only. This makes the engine turn slower at
    the same road speed, which will give you these things.

    But, the tradeoff is your accelleration will drop.

    I'm going to assume you want the better mpg because you
    want to commute long distances on a highway. The reason
    is that if your only going to be riding very short distances,
    your only maybe buying a tank of gas every month, so who
    the hell cares about mpg?

    Now, do you really want to be merging into highway traffic
    going 70mph from a freeway entrance ramp, on a bike that
    has compromised accelleration? Are you trying to get rear-ended?

    This is why people are saying this is a stupid idea. Your
    likely to get yourself killed.

    And as for 2 master links, that is also a stupid idea on a
    cruiser, unless your goal is to have the chain break and
    get wrapped around the rear sprocket and jam the rear
    wheel - at 70Mph on the same freeway.

    Ted Mittelstaedt, Aug 21, 2008
  18. Bill Miller.

    Bill Miller. Guest

    mind---i.e. better mileage, quieter top speed operation, less shifting
    in the lower ranges, etc.
    Okay, add teeth to rear sprocket only. Advice was what I was looking
    for, not denigration and criticism. Thank you. And I realize
    acceleration will drop.
    the hell cares about mpg?

    Your assumption is correct and so the second sentence will be ignored
    since it's inapplicable. The commute is approximately 1500 miles per
    month, about 70 miles round-trip every weekday and is over flat
    secondary paved backroads where I'll be traveling between 45 and 55
    mph most of the time.

    No, and my previous response also renders those two questions
    No, people are saying it's a stupid idea for no valid reason at all
    except just to lord their so-called knowledge over someone without
    paying any attention to the uniques situation posed by the poster.
    It's common for the pompous know-it-all freaks like TOG to do that.
    They're so wrapped up in their own opinions, they cannot see how
    someone else's situation could differ and how their ideas would be
    inapplicable to that situation. Sorta like you ASSUMING about the
    freeway and ASSUMING that it was a stupid idea because I could get
    myself killed. Both inapplicable to MY situation, maybe not others.
    Where do I start with the assumptions and inaccuracies?

    1--I never said anything about two master links. I believe that was
    stated by a responder to my post.

    2--It is not a "cruiser," it's a dual sport bike (TW200).

    3--70 mph on the freeway? No freeways involved and I wouldn't ride
    that bike 70 mph anywhere and I doubt it would even go that fast with
    my weight and what I would carry to work in a container on the back.

    But Ted, once we sifted out all the assumptions, at least you helped
    with the choice of the rear sprocket. And that's the idea of
    responding to posts. Analyzing exactly what is proposed, assuming
    NOTHING and then offer sound advice on the SPECIFICS of the post.

    Bill Miller., Aug 21, 2008
  19. Bill Miller.

    Bill Miller. Guest

    Just another useless, no-help, pompous response from the Chief Asshole
    of Reeky, the know-nothing sack of dogshit called The Older Gasbag
    Gentleman. And YOU are the only thing that is daft, you ignorant old
    Bill Miller., Aug 21, 2008
  20. Bill Miller.

    . Guest

    Gong! A rear sprocket with more teeth causes the engine to turn FASTER
    at the same highway speed, increasing overall torque multiplication,
    enhancing acceleration, and *possibly* causing the engine to burn more

    The typical performance rider *wants* more acceleration and is willing
    to give up some top speed to get a little more *apparent power* off
    the line, so he will either
    install a front sprocket with ONE less tooth, or a rear sprocket with
    THREE more teeth.

    This change typically drops the overall gear reduction about 7.5% and
    that's all that is practical. If he changes the overall gear reduction
    by, say 15%, that will effectively make his 5th gear into a 4th gear,
    and he's always going to be trying to upshift one more gear to reduce
    cruising RPM.

    OTOH, the OP wants to reduce cruising RPM and enhance mileage, so he
    install a rear sprocket with as many as THREE teeth LESS.

    The TW200 has a red mark on the speedometer at 55 mph, and this has
    fooled at least one rider into thinking that the engine is wound up
    tight at only 55, but the
    TW200 will go faster than that, as has been discussed on the TW200
    owner's forum.

    Installing a rear sprocket with with more than three teeth less than
    stock would result in the rider having to downshift for every slight
    hill or a headwind.
    ., Aug 21, 2008
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