Singlespeed/direct deive chain load (strain) estimate, anyone?

Discussion in 'Transmission / Drivetrain' started by FurryOnTheInside, Aug 7, 2016.

  1. FurryOnTheInside

    FurryOnTheInside Active Member

    I'm just wondering if anyone has any idea how much load is the chain carrying on a standard 10/44 kit setup.
    I have been looking for comparisons between the different standard chain sizes and finding only comparisons of the same size but different brands (those seem to differ far more by wear rate than BS), however the one chart I found showing different sizes of the same brand showed that their (DID) chains have the same average breaking strain (BS) no matter what size (1/8" or 3/16") except their "track racing" 1/8" which I am assuming has thicker side plates, possibly better material.
    I am just trying to figure out what the lightest, narrowest chain is that would work (if the sprockets were narrow enough to match).

    So yeah, in short what is the minimum BS necessary for direct drive motor chain?
     

  2. butre

    butre Well-Known Member

    regular old bmx chain holds up just fine, but the chain line has to be 100% perfect, don't want any loading in the wrong direction.
     
  3. FurryOnTheInside

    FurryOnTheInside Active Member

    Uh huh of course it wants to be straight. I'm sure quality 1/8" BMX chain is okay since 1/8" has the same BS as 3/16" , ATBE. Same side plates means same BS. (9000N+)
    I'm just wondering what the actual strain is or what the _minimum_ acceptable BS would be.
    Tbh the 9 speed 3/32" chains of decent brands are about the same BS.. 10 speed are lower BS but that's to be expected.
     
  4. butre

    butre Well-Known Member

    this only covers the common chain sizes but it'll do

    [​IMG]

    if I wanted to go with the minimum possible size I'd go with a #38, which has a tensile strength somewhere on the order of 3000 pounds and has an inner width of 3/16

    you could probably get away with a #37, which uses the same side plates as #38, but with smaller rollers (1/8th inner width) so I'd be concerned about the sprocket flexing or getting bent and the teeth wearing down too quickly.

    they both have the same half inch pitch as the #410 that the kits come with
     
  5. FurryOnTheInside

    FurryOnTheInside Active Member

    I think you attached the wrong picture, which confused the tihs out of me for a moment, haha.
    I take your point about the increased wear rate of a narrower chain and sprockets. The sprockets can be thicker than the teeth at the edge though so I doubt bending would be a problem. I just got a possibly silly idea in my head about a "dingle" sprocket set.
    Thanks for your input. :)
     
  6. libranskeptic

    libranskeptic Member

    just saying, or hunt up apps which place similar stresses on chains, and copy what they specify. Cargo bikes, concrete mixers...
     
  7. FurryOnTheInside

    FurryOnTheInside Active Member

    The dingle system is from fixie cycling but I am sort of convinced it's all moot because chain width affects wear rate (not worth it unless theres a decent advantage) and as there's little room for different sizes of front sprocket even with modification (little range difference, so little advantage), would take extensive modification at the very least, which I don't have the capability and tools to do.
    I still think a dingle is worth looking at for other single speed engines. Just not for me and the little Chinese generic bicycle engine with its enclosed drive sprocket.
     
  8. crassius

    crassius Well-Known Member

    I'd guess a 2000lb chain is OK for these - the 415 chain that comes with most kits works well when installed correctly - saving a 1/4lb there doesn't seem worth the effort (skipping breakfast would probably do more).
     
  9. FurryOnTheInside

    FurryOnTheInside Active Member

    I wasn't actually thinking about weight at all but outside width, and the possibility or not of a dingle system. Dingle is two sprockets front and rear, sharing (taking turns using) the same chain. Manually changed between the high and low ratio gearing (but without need of tools). I have become convinced it is only worth lookin into for other engines but not the Chinese generics because of the dimensional constraints and concentration of wear on narrow chains. Goggle the "Surly dingle sprocket" if my explanation sucks.
     
  10. crassius

    crassius Well-Known Member

    not sure how those are different from freewheel or cassette with only two sprockets on them
     
  11. FurryOnTheInside

    FurryOnTheInside Active Member

    They are, but Surly's explanation might be more understandable! They are to be used with two front sprockets, to make two different side-by-side single speed pairings that have different ratios: one for flat open riding, the other for hills/ in town.
    By having the same total tooth count, like 10:44 (54 total) and 14:40 (54 total) gives you a 1:4.4 and 1:2.86 ratio, and you can use the same chain but not have to split the chain to switch from one ratio to the other.
    It is not gears, but it gives a single speed more versatility.
    You have to get off the bike, release the chain tensioner or pull it out the way if it's a spring tensioner, and manually pull the single speed chain over to the ratio you want while turning the wheel by hand.
    It is certainly useful for pedal power bikes, but after a bit of thought I decided IMO not a big advantage on motored bikes.. unless there is a lot of room around the drive sprocket to get a second sprocket of a significantly larger tooth count (ie 10 and 14), and enough lateral space to use a 1/8" chain to spread wear and last longer than a 3/32". Still, it's an option that is out there but doesn't get mentioned so I had to have a think about it and see what potential it has.
     
    Last edited: Aug 13, 2016
  12. CrazyDan

    CrazyDan Member

    Decreasing the weight of any rotating mass that is sapping energy from your motor to the ground will have far greater benefits than losing even twice that weight anywhere else on the bike (including the breakfast that can reside in his stomach because he decreased his rotating mass). I find swapping my kit chain for an HD bmx chain increases my acceleration more than fasting for longer than I feel comfortable :p.
     
  13. FurryOnTheInside

    FurryOnTheInside Active Member

    Not that there is a difference in ultimate tensile strength between a 1/8" and a 3/16" chain, all things being equal. The strength is in the side plates. Some "track" 1/8" chains are actually slightly stronger than a 3/16" (DID for example).
    There is a difference in wear rate. If 1/8" lasts 100miles then 3/16" theoretically lasts 150miles and 3/32" lasts 75miles.
     
  14. crassius

    crassius Well-Known Member

    if I had room for two chains, I'd put them on free spinning sprockets and run a detent ball up from the inside of the shaft to lock the one I want to drive the rear
     
  15. FurryOnTheInside

    FurryOnTheInside Active Member

    I have no idea what you mean.. How a ball detent would do that.. Mm.
    Anyway you don't need room for two chains or the clearance space between them to do a dingle, with only one chain only one or other of the side plates needs to sit between the sprockets, so actually it's more like 1.75 chains wide. You do need the room for the chain to be pulled over the larger sprocket.
     
  16. crassius

    crassius Well-Known Member

    but them one doesn't seem able to shift it as one would other transmissions

    free spinning sprockets have small notches in the bottom where the ball fits to lock it to the shaft - to shift to other one, the ball gets moved inside shaft to catch opening under next one
     
  17. FurryOnTheInside

    FurryOnTheInside Active Member

    No, that's right, it's not gears, you do have to pull over and get off, but it can be done out on the side of the road. It's just a lot easier than the disassembly involved in changing a single speed rear sprocket and chain.

    I am really not able to picture how free spinning sprockets would work, what they spin on, how the position of the ball detent is controlled.. I'm lost. Sorry :oops::oops::oops:
     
  18. crassius

    crassius Well-Known Member

    old method from 20s thru WWII - haven't looked, but may be back now in paddle-shift cars
     
  19. Steve Best

    Steve Best Active Member

    Last edited: Aug 15, 2016
  20. FurryOnTheInside

    FurryOnTheInside Active Member

    If those figures are correct then you're not going to break any chain.
    Some half link chains have been said to stretch, due to the kink in the side plates.. But
    Most chains are around 9500 -10000N+ breaking strain. Even the cheapest nine and ten speed chains are at least 9100N according to what I have read with just a little online research. So size really doesn't matter.
    It really is only a question of wear rate. Better material lasts longer, and wider chain divides wear to last longer.
    Which is why I thought this thread had been put to bed, lol.
    Thanks to all those who contributed information. :)