OK, it's end of 2013 -what's the verdict on BB standards?

Discuss light weight issues concerning road bikes & parts.
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theosaurus
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by theosaurus

I find it very hard to believe that people don't find regular threaded crank systems stiff enough, even for track.
What I really don't understand is the new 'standard' bbs being used on cross bikes.
yes, but how much does it weigh?

by Weenie


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DMF
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by DMF

+1 on that, RED GXP isn't exactly a noodle. And as for the frame BB area, isn't that rather stiffness per weight ratio that increases. Not like you couldn't build a threaded 68-70mm BB area as stiff as you like, and its not like atleast the brand manufacturers aren't aware of exactly how stiff their BB areas will turn out... It's not like they're adding a couple layers of carbon cloth and taking a guess "uhm, that's probably good".

Let's agree you can make lighter frames for a given stiffness, no doubt. But ultimately stiffer frames? I call bikemag-brainwash/complete BS on that one...

Manufacturers don't aim for ultimate stiffness, they aim for a predetermined fixed stiffness number and the lowest weight route to get them there.

eric
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by eric

Weight Weenies is the last place I'd expect people to be retrogrouching against lighter technology.

One other advantage to BB30 and PF30 is better heel clearance. Some of us with large feet who pedal heels in have a problem with that.

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GonaSovereign
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by GonaSovereign

eric wrote:Weight Weenies is the last place I'd expect people to be retrogrouching against lighter technology.

And they wouldn't be if there wasn't such an obvious downside to the lighter technology.

I first bought into press-in systems in the early '90s, and I really wanted to like the newer OS press-in systems, but they aren't good enough. They're designed to benefit the builders, not the owners, and the problems have been downloaded to the people who need to live with the bikes. That sucks.

eric
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by eric

I find myself about to make the same arguments I have already made so I think we're just going in circles at this point.

tinozee
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by tinozee

I ride a Tarmac sl3 with english bb and sram red. I can't imagine what stiffer would feel like.

The only thing that makes me personally hesitate is the creak I keep hearing about, that would piss me off to no end. Why can't they just make a wider diameter threaded bb? Or maybe they do? There are so many variations I am not certain.

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DMF
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by DMF

Valid point if you ride heels in, have big feet and also require narrow q-factor. Seems like a bit of minority issue tbh though, when so many others suffer severely from the often occurring downsides. (Creaking, bearing migration, creaking, compatibility issues, increased drag, creaking...)

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bikerjulio
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Location: Welland, Ontario

by bikerjulio

Q factor is the biggest myth ever when it comes to modern (meaning the last 30 years or so) cranksets.

Q factor being the distance between the pedal mounting faces of the cranks.

There has been little or no change since forever, because:

Cranks have to clear the frame,

and

Heels at the back of the stroke have to clear the chainstays.

and

Crank manufacturers want to make this as tight as possible, and this has always been so.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

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DMF
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by DMF

Surely there has for the past 5-10 or so years been a bit of a race to lower q-factor, thinking lower was better (that would be the myth then), and only lately have we started to redeem this mistake, by offering longer spindles for pedals and so on...

But I distinctively recall there being a bit of a hysteria about going ever lower a few years back, and q-factor was a selling point...

I would ofcourse agree that lower isn't better, its very individual.

DartanianX
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Joined: Sun Nov 13, 2011 6:00 am

by DartanianX

Or this from FSA, threaded BB shells and BB386 cranks.

Image
Last edited by DartanianX on Sun Dec 01, 2013 11:13 am, edited 1 time in total.

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DMF
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by DMF

NICE!!!

Now make that GXP style interface and we've got a winner! :)

GT56
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Location: Switzerland

by GT56

bikerjulio wrote:Q factor is the biggest myth ever when it comes to modern (meaning the last 30 years or so) cranksets.

Q factor being the distance between the pedal mounting faces of the cranks.

There has been little or no change since forever, because:

Cranks have to clear the frame,

and

Heels at the back of the stroke have to clear the chainstays.

and

Crank manufacturers want to make this as tight as possible, and this has always been so.


+ 1

some BB30 cranks may present more clearance at the crank spindle, which is good for those with wide (flat) mid feet, but the distance between the mounting faces of the different (non triple) road bike systems (BB30 or not) are within 5 mm of each other

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DMF
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by DMF

Actually first gen Red cranks were 150mm for BSA and 145mm for BB30... Not saying 145mm wouldn't be possible with BSA, just stating the fact that sometimes the pressfit versions indeed have lower q-factor when it comes to the actual product.

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bikerjulio
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Location: Welland, Ontario

by bikerjulio

At best, modern cranksets are replicating the dimensions and clearances that were common 20+ years ago with square taper. The whole marketing thing that BB30 gave a lower Q factor is complete BS.

Current SRAM Red has a Q factor of 145mm whether in GXP or BB30 form. Makes no difference. Agreed that the BB30 may have marginally better heel clearance to the crank, but SRAM don't provide this dimension.

Measured a couple of older bikes with Record square taper.

C Record from around 1990 - Q factor is 145mm.
Alloy Record from around 2002 = Q factor is 145mm.

I'd suggest that any minor differences in Q factor that exist today are more to with crank design than anything to do with what BB is in use.
There's sometimes a buggy.
How many drivers does a buggy have?

One.

So let's just say I'm drivin' this buggy...
and if you fix your attitude you can ride along with me.

http://www.youtube.com/watch?v=GekiIMh4ZkM

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DMF
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Joined: Sat Dec 06, 2008 10:14 am
Location: Sweden

by DMF

Yes, I agree. Seem to recall Extralite went down to 138mm in BSA, so nothing to do with method of attachment, I was merely pointing out the actual fact that if you were riding Red a couple years back there was actually a difference between BSA and BB30 (nothing to do with what's possible, only what actually was). Those were the numbers I had at hand, but I'm fairly certain there have been other similar examples too...

by Weenie


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