1 vrs 3 piece crank question?

[beatcad]

yes i did search 1st so please dont grille me

so what is the deal?
i know both have been around forever but what is the advantage between the 2?
i might think the 3 piece might be stronger. modern alum ones of course are lighter, but old steel cottered cranks can't be.
1 piece cheaper to make?
i dunno. that's why i'm askin you guys.

 

[Bicycle808]

First thing to consider is what will even fit your frame..OPCs will only fit on frames with American bottom bracket shells.

So,if your frame has a BSA(aka"Euro") BB shell or a mid or spanish shell,or any of the other roadbike standards (eg,Italian, the new oversized stuff, weird whitworth/raleigh shells), the OPC is not even an option.

With so many different options for 3pc cranks, it's tough to compare 3pc to 1pc. I will say that OPCs are cheap, heavy, very easy to work on, not as adjustable in terms of chainline, and the cheapness factor gets skewed somewhat if you get a sealed-bearing BB. I will also say that most 3 pc cranks have a lot going for them, and I enjoy riding/working on most of them, but I despise cottered cranks. Other than that, there's just too much to discuss in terms of 3pc cranks.

 

[danthrift71]

+1 on cost. Assuming you have an American Bottom Brackett, OPCs are a great combo of low cost and durability. Modern chromoly tubular cranks like Redline Flight Cranks and their successors, have the edge in weight & strength but cost much more. $20 vs. $100 roughly retail. Aluminum 3-pc cranks, while light, just don't hold-up as well and cost more to produce. I've never owned cottered but have seen plenty mangled ones over the years.

 

[mikeeebikey]

Strength, I bend 1 piece cranks pedaling, yes I am a pretty big guy, 225#s of bad attitude fat leg pedal and crank destroying man! I have always been hard on cranks.
I run BMX 3 piecers on everything except my one "road," bike, which I never ride....It has Deore LX w/shimano clip ins.
1 piece cranks willnot fit small B.B. shells.
Dans comp. or dancomp.com has generic alloy 3 piece set up for less than a $100.00

 

[Bigcam59]

also, you can get bottom brackets that'll let you put a 3 piece crank in a 1 piece bottom bracket frame, but not the other way around.
1 piece are easy to work with if you have basic tools, and the chainrings are more easily interchangable...and some look pretty nice too!

 

[cashman]

The one piece crank is a lot easier to manufacture nowdays. Back when they first started putting pedals and chains on bikes, they probably lacked the ability to make one piece forgings like they do today. British and European manufacturerers have always stayed with the three piece design. As were all of the American built bikes from the 1800's to the early 1900's.

 

[SSG]

The three piece crank is as old as the bicycle itself. The 1 piece crank is probably solely for cost savings since it is a single forged piece which would make construction much simpler.

 

[Bicycle808]

I gotta say that, while i have seen some bent OPCs, I'm 250lbs and I've yet to bend an OPC while JRA.* True, BMX 3pc cranks are much stronger, and will better withstand abuse in the form of drops and hucking, but I can't see bending a OPC unless something else has gone wrong, or you've got a crazy high gear on it.

Also, not all OPCs are created equal. You can get hideously cheap ones from XMart bikes, which would probably bend easily. Or, you can get quality vintage ones or new-production chromoly versions from Redline and BlackOps; that's what I've been rolling lately, without any issues.

I will say that OPCs are very easyto dissemble and repack, which is good b/c you'll have to do that frequently.

*JRA= just ridin' around