How cheap are those kit 3 piece wide cranks made?

Discussion in 'General Questions' started by bikejock, May 20, 2015.

  1. bikejock

    bikejock Member

    I noticed a few days ago when working on my build these 3 piece wide pedal cranks seem to be made dirt cheap as in cheap quality. Honestly, I think they could make a better 3 piece crank with the money they are making on these 4 stroke kits. I ordered a few upgrades to improve my 3 piece wide crank so it doesn't feel like I'm pedaling a cheap bike. Everything from the arms, to the bearing cups, axle & sprocket feels very sub par in quality. The arms scratch very easily, the chain ring sprocket feels very flimsy and so does the bearing cup hardware. The only thing I see probably being decent quality is the included bearings. A bottom bracket & crank set should be made of reliable, better quality material otherwise it probably wont last long.
     

  2. butterbean

    butterbean Well-Known Member

    I'm building my own bottom bracket using a moped pedal crank and sealed bearings instead of a bearing cartridge. Once I get all the hardware together, I'll post links.
     
  3. bikejock

    bikejock Member

    Moped pedal crank parts... That's a good idea. I was thinking of finding a pair of moped pedal crank arms that would be better than the kit stuff. I found an axle that allows me to use the original chain ring & bearings and looks like its better quality than the kit pedal axle. Know of a source for quality crank arms & stuff like that? I wanna use crank arms with the same threading as the kit arms because they fit the pedals I wanna use.
     
  4. butterbean

    butterbean Well-Known Member

    I don't know much about what different parts fit together, but I buy all my moped parts from www.treatland.tv I got a rear hub from them and laced it into a 24" bicycle rim.
     
  5. butterbean

    butterbean Well-Known Member

    I don't think a bearing cartridge will work with a moped crank though, the moped cranks diameter is 16mm, and the smallest bicycle crank is 17mm, unless you can find a vintage bearing set, they may have been 16mm at one time but they aren't anymore, it would probably take a lot of searching around to find one that size. Thats why I went with sealed bearings instead, they will last longer than a beating cartridge anyway.
     
  6. bikejock

    bikejock Member

    Guess I'm stuck with the kit crank arms until I find better ones that fit. I'm getting an upgraded crank axle from phantombikes so I can use my chain ring that came on the bike & the original bearings & cups. The chain ring from my bike feels much more durable than the kit chain ring. It will need to be durable on my 4 stroke bike because it's HEAVY. I think most 4 stroke motorized bikes come out to around 40 lbs. But my 4 stroke build feels more like 60 or 70 lbs with the motor & other hardware installed. Pedaling on that much weight would be hard on the rear wheel (I assume)
     
  7. butterbean

    butterbean Well-Known Member

    Most cruiser frames weigh at least 40 lbs alone. With a kit, probably closer to 60-65. My last non-kit 4 stroke bike weighed at least 80. The one I'm building now will probably weigh about the same.
     
  8. bikejock

    bikejock Member

    Guess I was off on the weight of my current build. My bike is actualy fairly heavy even without the kit. My old 2 stroke was no where near how heavy my 4 stroke is turning out to be. Then again 4 strokes have more parts & bigger parts then 2 strokes. Hope it handles the my weight & the bikes weight.

    I might have to rethink my street legal hardware (lights turn signals mirrors etc.) to save weight. Most 12 volt batteries are pretty heavy to even tho they are small it would still add more weight to an already heavy bike.
     
  9. butterbean

    butterbean Well-Known Member

    My last engine only spun 5200 pms. With a heavy front drum wheel, 270lb rider, heavy hydraulic forks, lights, generator, battery, and saddlebags, it still hit it's top speed of 32 no problem. I wouldn't worry about the weight from the lights and battery. The motor can handle it.
     
  10. bikejock

    bikejock Member

    I'm around 170 lbs so it should handle my weight no problem. I might upgrade the tires to handle more weight & last longer.

    As much as I love the fireball tires on my bike, it looks like I gotta go from a 3 wide tire to a 2 wide in the rear because the chain might be bumping the tire to much. I'm considering moped wheels for increased durability.
     
  11. butterbean

    butterbean Well-Known Member

    I laced a moped hub to a 24" bicycle rim for my current project.
     
  12. bikejock

    bikejock Member

    That's a good idea. I would like to be able to use my original rims at least. Wish someone would market moped wheels designed specifically for motorized bikes.

    I might try lacing a moped hub on my rear wheel which is a 24 rim. My front wheel is a 26 but that shouldn't matter if I'm lacing a hub, right?
     
  13. butterbean

    butterbean Well-Known Member

    Having a bigger front wheel than rear will never hurt anything. You do need to make sure you calculate the correct spoke length for the hub and wheel you are lacing. There are online calculators that will do this for you if you take measurements of the hub and rim and put them into the calculator. Be forewarned, no bicycle shop will touch the wheel if it has a moped hub in it, so you must lace and true it yourself unless you live near a moped or scooter shop and are willing to pay their labor prices. You will also more than likely need to widen your rear dropouts to accept the moped hub, because it is much wider than a bicycle hub.
     
  14. The_Aleman

    The_Aleman Active Member

    The kit 3-piece cranks are generally garbage. Yeah, they'll work - to a point. If you want your stuff to last and be adaptable, you need to change up.

    I've used an SBP cartridge (like this) and SBP crank arms for almost 5 years and almost 10K miles, has served me very well.
    You will need an adapter for US BB to use most cartridge/sealed bearing sets with square taper ends. Many shorter crank arms are available.

    A quick FYI for anyone who don't know: 1-piece cranks take ½" pedals, while 3-piece cranks take 9/16". LHS always has left-hand thread.

    If you don't need freewheel cranks, then you'll need a fixed sprocket adapter, like this. Then a 24, 30, 36, 44, or 48T sprocket from them.

    If you want/need freewheel cranks, I've used both SBP standard freewheel and heavy-duty freewheel adapters. If you're not starting engine with cranks, standard is fine.

    Good pedal cranks are expensive, but in the long run are worth it. Of course you can get heavier-duty parts for less money and adapt them if you're clever.

    Always research!
     
    Last edited: May 24, 2015
  15. butterbean

    butterbean Well-Known Member

    Yeah, I have the crankset adapters. My plan is to use a moped pedal crank and 16x35x11mm sealed bearings. The sealed bearings will fit between the adapters, where a bearing cartridge would normally go. Then I'll just install a lock collar on the left hand side to hold it all together. Total cost for this setup is about $70 plus shipping.
     
  16. bikejock

    bikejock Member

    Ever used one of these before? Thought it was a great idea. Wish the kits included these. It's a special axle that allows me to use the original bike chain ring & original bearings so I don't gotta swap the cups & other bottom bracket hardware on my bike for the kit stuff. I ordered it from phantombikes for a little over $100. At that price you know it's better quality than the kit stuff. Hope it arrives soon.

    Crank Adapter.jpg
     
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