Need advice on pedal chain alignment

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dtv5403

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May 4, 2015
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I am going to be building custom wheels for my upcoming project, using a moped hub for the rear wheel. The moped hub is considerably wider than a bicycle hub, leading me to hypothesize that the pedal chain will not line up with the rear wheel. I'm not concerned about the engine drive chain alignment, as I'm using a 79cc predator and I will be able to adjust the drive chain to whatever position I need. What I am looking for is advice on how to build a bottom bracket that is adjustable as well. I've done some looking around and I know there are some bottom bracket kits available, but I'd prefer to source the parts myself and assemble to keep the cost lower, so if anyone can help me out with a list of parts or at least point me in the right direction of how to figure something out, that would be great. The bike is currently setup for a one piece crank but I have no problem converting if necessary. Any help/advice would be greatly appreciated.
 

dtv5403

New Member
May 4, 2015
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USA
I think I may have this figured out. I already have a bottom bracket conversion set. Last night I found a junked road bike frame (strangely enough, not missing anything but the wheels) in a trash pile. So I may be able to use the bearings and hardware from that, but I will need to measure the shaft diameter first and I dont have any calipers handy to do so but I can figure that out. Anyway, I went on a moped site, treatland.tv, and found a moped crank for sale for $28. The pedal sprocket is welded on. The length is 260mm and the shaft diameter is 16mm. So if the shaft on the road bike frame is 16mm, then I should be able to use the bearings and hardware out of that, and even if not the proper size bearings cant be that expensive, maybe need a couple spacers to get the alignment right, but I couldnt make my own bottom bracket this cheap on account of not owning a welder. This should work just fine.
 

dtv5403

New Member
May 4, 2015
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USA
Now I'm not too sure, because I'm reading that most three piece cranks are 9/16", and the moped shaft is 16mm, which is a hair over 5/8. So I don't think any bicycle bearing cartridge will fit. now if I can use other types of bearings, that would be fine as well.
 

dtv5403

New Member
May 4, 2015
322
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USA
I may have to use regular sealed bearings and lock collars like would be used on a jackshaft, instead of a bottom bracket cartridge.
 

dtv5403

New Member
May 4, 2015
322
1
0
USA
Nevermind, 9/16 is the pedal axle diameter, not the crank diameter. I cant seem to find any info on the actual spindle diameter, which is kinda irritating.