Bottom Bracket Conversion

[LukeTheJoker]

I "feel" the same way about the bigger (6, 8, 10, or 16)spline set-ups, but everything I read suggests otherwise, as do discussions with my engineering and mechanic buddies. Apparently, the finer 48 spline set-ups are stiffer, and less prone to stripping b/c the load is spread out among many more splines. I guess it makes sense, and the same is basically true for fasteners, at least as far as strength of the bolt but I do find that the finer threads strip easier....

At any rate, something like a Redline Flight, with 6 splines and double pinch bolts, is just so easy to set-up, and it's definitely as stiff as I'm gonna need. Yeah, I flex it a little when I'm riding hard, but I'm a fat guy on a hi-ten frame doing things that the equipment was never intended to do. When I ride a bike with a euro conversion and a square taper crank, I flex it just riding around. Not b/c i'm some sort of beast-mode powerhouse, but b/c I weigh a cool 245lbs...

I have read the same too, I guess it works the same way as diff axle splines...
Usually the higher amount of splines-the better.

Totally agree on fine threads too... Sometimes things just work the opposite of what you would expect.

If you look at rough use equipment, e.g. mining, they tend to use less but bigger splines, I think that is more to do with wear and longevity though...

Whatever the case, those 3 piece BMX cranks are pretty awesome!

Luke.

 

[mornview]

Oh, I wasn't thinking that you were implying anything like that; i'm thinking it's awesome for you to give the advice as someone who went thru all this recently, whereas I tend to assume that folks have more experience/specialized knowledge than neophytes often would.....

I understand the appeal of loose bearings versus cartridge bearings in terms of DIY ethos and (arguably) less waste, but I gotta say, those square-taper cartridge units from reputable manufactures, they last a VERY long time, and require dang-near zero maintenance. Considering that you'll go through a ton of grease and a couple sets of balls in the time it takes to kill one cartridge set, waste isn't really a factor, but the cartridges do cut down on the DIY aspect a bit-- mostly b/c there's less to do.

As for bmx-type 3 pieces, most of these will have sealed cartridge bearings, and they'll be replaceable, meaning you can pull the cartridge out and snap a fresh one (most all are standard sized) into the cups. I like examples with pinch bolts, but other popular manufacturers make some where they're simply held on by the crank bolt. These things tend to be steel, they tend to have splined axles (aka spindles), they tend to be overbuilt for casual riders/commuters/cruisers, but they're stiff and tough for klunkin duty or any other kind of 2-wheeled mayhem. Here's a pic of a Redline Flight crank on my Worksman INB: (scroll down) http://www.ratrodbikes.com/forum/index.php?threads/3-piece-crankset-on-cruiser-frame.86047/ Probably overkill for most folks' riding, but they handle my 250lbs ont rails without a hiccup, and (IMHO) they look pretty BtotheA

This has to be one of the most polite conversations to take place on the internet .

I guess that's a good way of framing the cartridge bb/cone & cup bb debate. Admittedly, based on my first few rides on my new cottered-to-cotterless cartridge bottom bracket conversion, this setup is pretty silky smooth .

I've gotta say, too, those BMX cranks are actually pretty sweet. I don't tend to associate BMX with aesthetically appealing, but those things really wouldn't look all that out of place on either of my builds. I'll have to look into them some more.

 

[Bicycle808]

I gotta take some pics of my Super Sport with the Flights on it; I'd worried that it'd look out of place, but it actually looks pretty classy, imo....

And, yeah, thanks for the awesome manners, as always. RRB keeps my faith in humanity alive....

 

[Bland_JamesBland]

I was originally going to go with a Euro BB conversion, but not I'm convinced on getting a BMX 3-piece set. I found some sweet Matte Red and Matte Orange ones that are the large coarse 8 spline with pinch bolts. My step-son has a BMX bike with similar ones and they've held up to some major abuse so I wouldn't be worried on a cruiser bike. My only worry is that I won't be able to use/find a large enough chain ring to work with the cranks... or am I looking in the wrong places? Sorry to Hijack.

 

[Bicycle808]

I was originally going to go with a Euro BB conversion, but not I'm convinced on getting a BMX 3-piece set. I found some sweet Matte Red and Matte Orange ones that are the large coarse 8 spline with pinch bolts. My step-son has a BMX bike with similar ones and they've held up to some major abuse so I wouldn't be worried on a cruiser bike. My only worry is that I won't be able to use/find a large enough chain ring to work with the cranks... or am I looking in the wrong places? Sorry to Hijack.

What size do you want?

FWIW, you can typically run a OPC sprocket on a tubular bmx crank with the right hat spacer; you need the 15/16"-to-19mm (usually), but some cranks take 20mm, 22mm, or 7/8" spindles so you just gotta match that up.... Porkchop has those hat spacers. Profile Racing has some awesome old-stock sprockets in big sizes (like 48 and 46t). A truly versatile solution is to run a spider; they're typically 110mm bcd and then you can run any chainring from 34t up to like 52t, in most sizes.....

Let me know what you're working with and what you're looking for, and I can probably point you at some links....

 

[Bland_JamesBland]

These are the cranks I've ordered and the Redline BB kit. Want a 37-40t chain ring.... but I should be able to use the ring that came with my Schwinn bike maybe?

 

[Bicycle808]

Nice cranks; they run a 19mm spindle. You can run a OPC sprocket or any bmx sprocket you like on them you like on them, with the proper hat washer (or, in the case of a sprocket with a 19mm center boe, no hat washer at all.) If your Schwinn sprocket is made of steel and designed for an OPC, go to this page and rder "Option A".... http://porkchopbmx.com/Chainwheel-Crank-Spindle-Adapter-OPC-19mm-20mm-22mm-7-8-SKIMCA01.htm I used this washer on my Super Sport with Redline Flight cranks and a Chicago Schwinn Clover sprocket....

Here's a killer deal on a sick sprocket: http://www.profileracing.com/estore/product.php?productId=9
They come in colors and there's a few 39t and 40t options. They will come with a hat washer....

More options here http://porkchopbmx.com/Chainwheels_c82.htm

HTH; there's a million other options out there too...

 

[Bland_JamesBland]

Thanks again 808 - you're a ton of help!

 

[Bicycle808]

Happy to help.

 

[jamesdart]

I kept thinking of trying to setup the Schwinn clover with a 3pc. That's my favorite sprocket, even though it's popular enough for everyone to copy it.