3 inch wide tire question

Discussion in 'General Questions' started by bikejock, Apr 30, 2015.

  1. bikejock

    bikejock Member

    I'm about to start installing my 4G bicycle engine kit on my crusier and it has a pretty wide rear tire. I was wondering, is this going to be an issue with chain clearance? Should the 415 chain be able to move OK without bumping aganst my tire?

    I've seen the 4G kit installed on a magargi stealth cruiser which has a tire width of a little over 2 inches. My rear tire is one of the thicker than usual bike tires (24x3) Has anyone ever had problems with a 4G kit using the 415 chain on a bike with a 3 inch wide rear tire? I would hate to have those tires ruined by the 415 chain because my rear tire is pretty hard to find now.
     

  2. butre

    butre Well-Known Member

    there should be clearance but if it's touching it'll be touching lightly. worst case scenario you might have to dish the rim towards the pedal side.
     
  3. Purple Haze

    Purple Haze Active Member

    You will have to keep the tensioner adjusted so there's no slop in the chain. Even better would be to install a spring-loaded tensioner. The rear tire is a pain to remove once your kit is installed, so do everything you can to protect the tire.
     
  4. bikejock

    bikejock Member

    I'm planing on going tensionerless with this build. I had a few bad experences with a tensioner/idler wheel on my last build. To me, it's just another part that puts other parts of the bike & the engine at risk. I'm just going to shorten the chain to the point of it not needing a tensioner/idler wheel.
     
  5. butre

    butre Well-Known Member

    you will probably end up needing a half link then. or even better, stick a derailleur on the pedal side and let it do your pedal side tensioning, while the drive side is a straight shot with no weak links. shift kit is also an option if you got an extra $150 or so to spend on your build
     
  6. bikejock

    bikejock Member

    I pared my chain with my tire and it looks like it should move fine without bumping it much. I won't know more until I take it on its first test drive. Looks like I gotta cut or bend my fender so the chain isn't rubbing aganst it.

    The rear fender on my bike was designed to match up with the 3 wide rear tire which looks cool but gets in the way of the chain. I'm thinking of cutting a slit at a certain point and bending the area the chain goes through so I can still use my rear fender.
     
  7. jaguar

    jaguar Well-Known Member

    Why don't you make a sheet metal tire guard?
     
  8. bikejock

    bikejock Member

    That's not a bad idea. I might try that but I also want to preserve the look of the bike. I might make something out of an old chain guard I have from an old bike which I could proabably shape in to a tire guard of some kind.
     
  9. KCvale

    KCvale Motorized Bicycle Vendor

    4G with a 100 tooth fixed T-belt pulley and 18T freewheel sprocket?
    Coaster brake single speed Fito?

    Yes, you can make it work.
    You need the back sprocket cupped out until it's wider than outside of big tires, and then mount the engine to the left so the unmovable sprocket is outside the tire too.

    You need at least 1/4" from the fattest part of the tread in a straight line between the 2 sprockets to keep the chain from rubbing on the tire.
    I generally wont mess with direct driving fat tires, the pedal side already has chain line that clears and you get gears as a bonus.

    You can't 'bend' a 415 chain around a tire wider than it's 2 sprockets width and chain path like you can a thin 7-speed chain.
     
  10. bikejock

    bikejock Member

    Tried installing my sprocket today but then noticed I got something wrong in the sprocket clamp assembly and noticed one of the nuts became stuck on one of the bolts. I can twist the nut on the bolt freely but does not unscrew off the bolt. I think the thread was damaged on the bolt so I'll have to get a bolt cuter and cut it off and request a replacement bolt. On the upside everything in the sprocket assembly seems to fit even with the grease cap on but I'll need to bend my coaster brake arm. I'm thinking of going with a jack shaft kit someday so I can bypass all this rear wheel sprocket stuff. I was thinking of installing a 3 or 5 speed cruiser style rear hub transmission anyway at some point.
     
  11. KCvale

    KCvale Motorized Bicycle Vendor

    Just take one up to the hardware store, it doesn't have to be metric, just the same diameter and length.

    I find a 3-speed internal hub on a shifter to be ideal.
    Just remember that on a shifter you loose your coaster brake so it needs alternate rear brakes.
     
  12. butre

    butre Well-Known Member

    while you're at the hardware store, replace all 9 nuts and bolts with grade 8 stuff and buy a tube of loctite
     
  13. bikejock

    bikejock Member

    I'll keep that in mind and invest in a 3 speed when I decide to shift. I could proabably get away with just having a front drum brake if I'm willing to sacrifice my coaster brake for the shifter hub but that's later down the road

    Getting everything installed is priority number 1 this month. I'm just so glad everything fits on my crusier.

    There's been a few setbacks like that nut stuck on that bolt in the sprocket and I gotta go get my old bearing cups removed at a shop because they won't budge and I don't have tools good enough to pull them out.

    I should have everything finished and up and running by the end of this month.
     
  14. bikejock

    bikejock Member


    I should. These bolts and nuts feel pretty cheap and I'm sure the hardware store near my house has the same size only better quality.
     
  15. KCvale

    KCvale Motorized Bicycle Vendor

    Naw, BB cups are easy to get out and you don't pull them out, you push them out.

    All you need is a light sledge hammer and long socket extension or similar hard long metal rod.
    Push the rod through one side to the far cup and whack it on the edges.
    Beware! They fly out!

    It's helpful to take a 1/4 round file to the BB inside to make it easier for the next cups to go in.
    That same sledge hammer and a block of wood will help you get the new cups in.
     
  16. bikejock

    bikejock Member

    I borrowed a file and a sledge from my neighbor and gave it a try and they just won't budge (and yes I am trying to push them out.) I think after all this time the bottom bracket shrunk slightly to the point where it tightened around the cups making them harder to remove. I wish these things would just unscrew like other bottom bracket components do. Looks like I'll need to take it to the shop to get them removed. They said it costs only $10 to swap the cups and I'll just install the crank myself.
     
  17. KCvale

    KCvale Motorized Bicycle Vendor

    The BB cups you have are just silver cups for 1 piece cranks, no connecting bolts right?
    They are just pressed in and no, your BB didn't shrink hehe ;-}

    The bike shop will do the same thing, just charge ya $10.
    A nice long heavy blunt shaft and big hammer is the only way to take them out.
     
  18. bikejock

    bikejock Member

    I checked the chain clearance for the tire today and it looks like there's just barely enough clearance for operation. I still would need to cut or bend my rear fender.

    020.jpg
     
  19. KCvale

    KCvale Motorized Bicycle Vendor

    Yep.
    Unlike the right side of your fender that is bent in to allow the pedal chain to pass, you need to make your own for the left side.
     
  20. bikejock

    bikejock Member

    What tools would you recommend for bending a fender? I don't want to use anything that would scratch or crack my fender.
     
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