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so why do companies NOT use threaded bottom brackets

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#2 ·
some of the other bb options allow for larger dia crank spindle, which is supposed to be lighter and stiffer.

im still on threaded bbs on both bikes...would be interested to hear from people if they really notice much improvement with the newer standards because it sure is a hellofa pain in the ass when you try and swap your stuff to a new frame
 
#4 ·
Threaded BBs work great IMHO. They are easy to replace, silent and cheap. I'm now on PF BBs and they are not as smooth. On one bike I cant stop the creaking. I fear the day I need to replace them.

Im sure its more marketing than real performance improvement. But we cyclist keep buying latest and "greatest".
 
#5 ·
I agree with 2tone, but don't actually know. The bbshell could be thinner (lighter) since the shell isn't threaded and that's less labor too.
 
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#6 ·
dbhammercycle said:
I agree with 2tone, but don't actually know. The bbshell could be thinner (lighter) since the shell isn't threaded and that's less labor too.
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So why do SC frames weight the same or very close to counterparts with that craptastic new advance?

You don't have to be an engineer, just have common sense. Think about a threaded BB and it's attachment to the frame. Now think about the pressfit with plastic cups between the frame and BB and how much force there is with you mashing the pedals- yup improvement my ass.

I just bought a Lenz frame, going to it from a TBc both threaded. Now I switch over my XT cranks and BB to the Lenz. No problem since it was threaded. Well the XT with a 30t ring didn't clear the chainstay, so I order XX1 GPX BB.

unscrew the XT bb and install the XX1 BB - nice and easy, wouldn't have been the same if these were pressfit frames.
 
#8 ·
It does also allow for a wider downtube/seat tube junction in the frame since it goes over the outside of the bearings, which should make a stiffer front triangle assuming they know what they are doing. I'm sure many people on here will tell you how horrible they are, but I have had several different pressfit BB frames(PF30, BB92 & even BB86 on a couple road bikes). So far I have never had an issue with any of them and I install all my own BB's. Press in head set bearing cups have been the norm for years and they work great. On the bright side, regarding tools, at least when you finally buy the tools to install HS's you can use them at the BB too now ;)
 
#9 ·
phatfreeheeler said:
It does also allow for a wider downtube/seat tube junction in the frame since it goes over the outside of the bearings, which should make a stiffer front triangle assuming they know what they are doing. I'm sure many people on here will tell you how horrible they are, but I have had several different pressfit BB frames(PF30, BB92 & even BB86 on a couple road bikes). So far I have never had an issue with any of them and I install all my own BB's. Press in head set bearing cups have been the norm for years and they work great. On the bright side, regarding tools, at least when you finally buy the tools to install HS's you can use them at the BB too now ;)
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Yea I see what you mean, it's a common complaint from SC riders that the front triangle isn't stiff enough. :nono:
 
#10 ·
nauc said:
are press fit lighter or cheaper or what

thanks
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Cheaper to make.

On carbon frames, a threaded BB shell has to be bonded onto the cut and faced surface of the frame (or built into the mold and installed during lay up).

On Alu/steel the BB shell needs tapping after forging/machining/extruding to shape.

Press fits allow you to remove those processes and save a couple of dollars per frame, which rapidly stacks up. As an incidental PF BB shells have a shorter lifespan than threaded ones (barring bad mechanics) since the shell tends to wear with repeated installs and lose it's grip, this is surprisingly handy for driving new sales.

The arguments regarding Chainstay and attachment widths are pretty hollow, that's dictated by crank, mech, tyre and heel clearance and isn't particularly different on PF frames. Weight is a dumb argument too, reducing a product's life span by years for the sake of single digit grams is not good for the consumer.
 
#16 ·
It's possible to make a strong & secure press fit BB, for instance lots of BMX bikes use them and they work well there. But the way it's done in a BMX is quite different from the half-baked crap in the mountain bike world. BMX bikes have a strong metal BB shell and the bearings are pressed in there real good, it's a tighter and much more solid fit than what's seen on mountain bikes. Everything is metal, and once you get the bearings in there they ain't moving.

You can't do that with a carbon frame since it'll scrape the crap out of the carbon so you'll need a metal insert in the BB area. And it's gotta be a pretty solid one too to handle a proper press fit. And it needs to be properly faced, reamed, and aligned. But that costs money, so it's either not done or not done properly. Which is why press fit BBs on most mountain bikes are a never ending source of problems.
 
#17 ·
Fix the Spade said:
Cheaper to make.

On carbon frames, a threaded BB shell has to be bonded onto the cut and faced surface of the frame (or built into the mold and installed during lay up).

On Alu/steel the BB shell needs tapping after forging/machining/extruding to shape.

Press fits allow you to remove those processes and save a couple of dollars per frame, which rapidly stacks up. As an incidental PF BB shells have a shorter lifespan than threaded ones (barring bad mechanics) since the shell tends to wear with repeated installs and lose it's grip, this is surprisingly handy for driving new sales.

The arguments regarding Chainstay and attachment widths are pretty hollow, that's dictated by crank, mech, tyre and heel clearance and isn't particularly different on PF frames. Weight is a dumb argument too, reducing a product's life span by years for the sake of single digit grams is not good for the consumer.
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This. Carbon is great for big structural components, but it's not good for small things. The size of a carbon strand is huge compared to a metal grain. So that said, it's very difficult to make small parts out of carbon. Sram even tried to fool everyone back in the late 90s and early 2000s with their "Carbon knuckle" 9.0SL derailleurs, but they were just plastic with a top layer that looked like CF. An english BB is a small structure relatively that has to be bonded to the frame. The bigger the BB is, the better the interface is going to be to the carbon frame.
 
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#19 ·
I remember working on my BMX bike back in the day with a press fit BB and was so envious of mtb's with their fancy threaded "English" BB's that was so much easier to work on. Even with the older ISIS mtb BB's before the outboard bearings, it was much better than the press fit BMX stuff.

I believe most BMX / 20" frames are now threaded and Mtn bikes took a step back and switched to press fit. I know the company speak reasons for press fit, but I think most people on this thread hit the nail on the head.

I'm so happy that Santa Cruz is my chosen frame brand and that they have resisted the press fit trend.
 
#20 ·
Yeah well the bearings in those threaded cups are pressed in. Headsets press in and the ones that seem prevalent today you just put the bearings in by hand. A fork is a much longer lever than a crank arm. I have press fit bb in my road bike and the wife's too. Been fine although she doesn't it much these days and I do ride off road more than on. I don't think there is anything with press fit perse, but it has to be done correctly. Not like regular bb's never creaked. Remember ISIS?
 
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