Solution to 3 piece crank

Discussion in 'Frame Mounted Engines' started by nsideus, Jan 1, 2009.

  1. nsideus

    nsideus Guest

    First I would like to thank the member who called me with this.
    Anyone who has bought the new Grubee 4-stroke knows about the problem with the new 3-piece cranks they are for european bottom brackets and the convertion kit cost $29.00 at sick bikes and $35.00 at bicycle-engines. The majority of bike frames that fit these kits are cruiser type with 1-piece cranks.

    I pulled a crank out of a 20" next bike and put into my schwinn point beach.
    This crank has the same arm lenth as the new 3-piece crank 6". The only problem I encountered was the crank hitting the exhaust pipe. The pipe can be pushed over to clear but I felt it would put too much strain on the manifold bolts and opted for cutting and old pipe which I may weld to correct the clearance, leave cause it sounds cool or reinstall the exhaust that comes on the engine. My feet don't hit the engine and I don't feel so bull legged.
    I feel this is a better solution than the convertion kit as once you see one of these new 3-piece cranks you know they are weak, did I mention weak.
    Excuse the dirt and grease she has apx. 2,700 miles on her.
     

    Attached Files:


  2. srdavo

    srdavo Active Member

    Sweet Cure!!! (gotta love the Schwinn!...btw)

    Nice looking ride.... way to go.

    how is the gearbox working out?? sounding?
    oh...lol ya can't hear it, cause ya got no muffler....hahaha

    seriously.... keep us informed about your gearbox performance.
    thanks
     
    Last edited: Jan 1, 2009
  3. graucho

    graucho Active Member

    I agree. And im also digg'in your chain tensioner. Good job.
     
  4. nsideus

    nsideus Guest

    Made a simple muffler to reduce the noise and add a little back pressure.
    2 3/4" to 1/2" reducers and a 3/4" 45 degree coupling.
     

    Attached Files:

  5. Irish John

    Irish John Guest

    The only real solution to the 3 piece crank problem is for as many members as possible to lobby Bicycle-Engines.Com and ask them to ask Don Grube to change back to the old 1 piece crank as the standard crank sold with 4-stroke kits. Don told me he changed to the 3 piece because Bicycle-Engines.Com asked him to and why they asked him to has never been explained. Maybe they hoped it would sell to people with MTB frames who wanted to try the 4-stroke. Whatever the reason it is a disaster and is costing us dearly. There are no 1 piece cranks available right now and the 3 piece is totally hopeless with shorter crank arms and harder to pedal etc not to mention its incredible ugliness. I implore people to write to Bicycle-Engines.Com and express their concerns and ask for the 1 piece crank to be reinstated as standard in the kits.
    Incidentally it's worth spending an extra $5 and using heavy duty bearings with those 1 piece cranks because the leverage from the extra width really puts a lot of force on the standard bearings.
    I see that Bicycle-Engines.Com are still recommending the wet gearbox solution for the Grubee gearbox even though we all tried it last June and by July we'd practically all agreed that the lithium grease worked much better and all this knowledge is posted on threads right here for people to read.
     
  6. nsideus

    nsideus Guest

    Irish, I have called BE.com about the cranks but as you know their next order probably wont be here untill August, September, October .... I am just showing and alternative to the 3-piece untill they are back in the kit. I will though call them again.
    Your right about what to use in the gear box and we found the right answer right here.
    This forum is where the manufactuers should look for what the riders want.
     
  7. nsideus

    nsideus Guest

    Here is a few more pics of the crank and tensioner for those inquiring minds
    also a emt exhaust pipe not complete just a temporary install. Note the grease, dirt and salt binding agents these insure the bike will not spontaneously destruct but slowly slide apart.
     

    Attached Files:

  8. Irish John

    Irish John Guest

    Thanks for those pics Nsideus, the Point Beach Cruiser is pretty good for motorising given it has 2 decent brakes. They don't sell them in Australia that I'm aware of. Your crank solution is only of use to someone who can access a Next bike and I have never seen them in Australia. The crank doesn't look like it's much wider than standard cruiser cranks but I believe you when you say it's 6" wide.
    I notice you have what looks like a 56T sprocket on your bike and, if so, I wonder how you can stand the extra revs, vibrations and slower speed. Nearly all of us find it the totally wrong sprocket for the 11T freewheel drive and opt for the easily available 48T. Don Grube says that his new kits will have the 48T as standard. It just shows you that these guys definitely DON'T test their products cos it only takes one good ride to find out that the 56T is totally useless and shortens the motors life by keeping the engine at full revs just to cruise at a reasonable speed. The other thing is it makes the clearance problem worse as well as any wobble if the sprocket isn't absolutely true in alignment. I have scanned many sprocket wheels and then fed the image into Autocad and it is there that I find out that they are never quite circular so even if you get it mounted true it will always wobble up and down - that's why the chain tension varies when you revolve the wheel.
     
    Last edited by a moderator: Jan 11, 2009
  9. The pearl

    The pearl New Member

    I like the derailer used as a tensioner. I bet it works better than the regular tensioner that comes with most kits. does it?
     
  10. nsideus

    nsideus Guest

    Irish, The bike doesn't need to be a next any short crank from a large BB should work.
    The 6" measurement which after I remeasured is actually 5 1/2" this is from the center of bend (where the crank goes through the BB) to the center of pedal hole.
    Yes I am running a 56T this is because I live in the foot hills and ride in the snow. I climb three hills in 5 mi and still need to pedal up each with the 56T. I put a 50T on this summer and really liked the extra speed but pedaling your arse off on every grade does have drawbacks. A 48T where I live would be the same as not having a engine at all. IMHO a 48T with the kit is as bad as the 3-piece crank. Grubee I won't comment on....

    Pearl, yes it is much better.
     
  11. Irish John

    Irish John Guest

    Nsideus, I believe you about living up hills that are incredibly steep but your case is an exception and your need for a 56T sprocket is also an exception and puts you in a minority of users. The majority of users find the 48T perfect for the Honda and good enough for the HS given that 50Ts are hard to come by. If you ever feel left out when Grubee include the 48T as standard in future kits let me offer to give you all the 56Ts I have in my garage. That is one from every kit I've bought so far - 8 so far and rising!
    You are welcome to as many as you want for free but to say that making the 48T standard is as silly as the 3 piece crank fiasco is really divorced from the reality of these pages because firstly, the 3 piece is incredibly ugly whilst any sprocket wheel size looks pretty much the same and secondly there was absolutely no reason to change to the 3 piece given that all 4-stroke frame mounts go into cruiser frames that take the 1 piece. If you read these pages you will find that very few people with 4-strokes use the 56t and very few like the 3 piece sprocket. I don't really give a rat's **** because I have enough i piece cranks and 48T sprockets for my own use but I sell built bikes to first-time novices and even they, after just one glance, won't accept a 3 piece crank and after 2 days of riding would be hammering on my door asking for a smaller sprocket if I gave them the 56T. NOBODY will accept a 3 piece crank and I'm a good blarney-merchant. They just can't stand the look of them on an expensive cruiser. I too live in a mountainous area in the middle of the largest vocanic crater in the southern hemisphere but my Honda with a 48T will climb almost all the back roads no matter how steep. It takes people a few days to learn how to take a run at certain hills but it's infinitely better than life with a 56T. I know because I've seriously tried 44T, 48T and 56T. Your case is exceptional and the conditions you encounter call for an exceptional sprocket size. I have been known to fit a 56t on a Grubee for a very old man because I wanted to slow him down but he too was an exceptional case.
     
    Last edited by a moderator: Feb 7, 2009
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