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PostPosted: Thu Jun 09, 2005 2:05 am 
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By going Ti the Deda DPower combo for instance drops from DA10 level of stiffness to Centaur grade. Another big drop is from Record (30% stiffer) to FSA Ultimax Ti or TA Axix Ti.


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PostPosted: Thu Jun 09, 2005 2:38 am 
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Location: USA
Quote:
Campa/Phil/etc. bb's are still going strong, absolutely fine for most purposes, after how many years now?


I'm in total agreement with you on the stiffness thing. I don't think that's the primary issue Isis was trying to resolve. In fact, if you think about the main parties involved in setting the standard, you have to keep in mind that they are very much about solid, accurate standards.

One of the big problems Isis was trying to solve was the wear to the spindle and the crank which allowed the crank to move closer to the BB every time you pull it off and re-install it.

Another problem was durability, while stiffness is involved, it's not quite the exact problem. Doing a 10 foot drop-off and taking the landing on the pedals, I'm sure plenty of people were bending JIS spindles. That's why Isis has been around in MTBing for so long. Why it's even being adapted to road cycling is really a puzzle to me, seeing as Campy has been doing so well for so long.

Outside of redesigning the BB and the frame to go with it, I think outboard bearings are the most logical way to go for more "stiffness" in road cycling. Really, manufacturers need to stop trying to use the same products for both road and mtn biking. I think after 20-odd years of the mountain bike, it's time the technology and engineering diverge and different standards emerge.

**edit** Meant to add the link to CK's Isis standard: http://www.chrisking.com/bb/bb_ISIS.html


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Posted: Thu Jun 09, 2005 2:38 am 


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PostPosted: Thu Jun 09, 2005 2:45 am 
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Joined: Tue May 03, 2005 2:20 am
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Location: Belgium
Hi,

Quote:
Yes, there is a flaw: by moving the bb shell inboard towards the seatpost as you suggest, there would be a greater and perhaps impossible restriction on chainstay design/diameter/etc.; not a minor consideration.


I'm not moving the BB shell, all I'm saying is that there's unused space on the outer side that can be used to expand the diameter of the shell at the extremes.
There's nothing I can see that would be getting in the way nor would it by any means upset the geometry of the frame, interfere with the chainline or allignment of any existing crank for that matter.

Essentially it would not be that different from Shimano's system, the difference is that they've wasted an opportunity by sticking to all existing standards for 100% backwards compatibility.
IOW, and I may be wrong, I've as yet not seen a "standard" frame that sports a downtube as wide as the BB shell.
The widest ones were invariably hydroformed alu frames.
Although carbon would allow to do the exact same downtube design, there's just no point in it.
So you end up with unused space at the end of the shell, space I'd like to see used to make stiffer BB bearing assys.
Whether that is a good idea remains to be seen but so far I can't see anything that would throw the idea straight out of the window.

Sorry if my shabby explanations are the cause of confusion, a simple drawing would clarify it much quicker no doubt.

Quote:
Finally, to repeat: this is where these stiffness issues get ridiculous: if component A) is stiff enough that there is no discernable flex and negative effect on performance who gives a d#%n if component B) is 1%, 10%, or 10,000% stiffer, really? Campa/Phil/etc. bb's are still going strong, absolutely fine for most purposes, after how many years now?


I feel the crux of the exercise is to make lighter BBs without compromising stiffness.
I agree with you entirely that there's no point in making a stiffer BB than strictly necessary.
However there is a point in making things lighter at equal stiffness.
After all the less Watts wasted the better the results of the racer are likely to be all else kept equal, no?
If you lose even a few miliwatts of power in a BB per revolution imagine the amount of energy wasted over a six hour race....
Stiffer BBs simply make for more efficient transmission of power.
Remember, anything that can move loses energy...
The only movement we want from our bike is one forward :smartass:

Quote:
By going Ti the Deda DPower combo for instance drops from DA10 level of stiffness to Centaur grade. Another big drop is from Record (30% stiffer) to FSA Ultimax Ti or TA Axix Ti.


Sorry to say so but that's just cheap engineering on the part of the parties involved.
We all know it's not the Ti spindle's fault even though the material is of course less stiff as we all know.
Just that they took a design optimized for a steel spindle and swapped that one for a Ti one....
Because the market wants a lighter BB, or so they think.
IMHO the market wants a lighter BB that just as stiff as the heavier one, that's all.....

In the meantime it pays to know what you're wasting money on and what's worth buying.
To me at least that's what true ww'ing should be all about.....

Ciao, :wink:

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PostPosted: Thu Jun 09, 2005 3:03 am 
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Joined: Tue Nov 30, 2004 4:25 am
Posts: 1140
Location: Tas, Aus
Thanks for the replies fellas. So anyone got any reliability comparisons between these two, ie how long do you think each should last? In the words of fdegrove I want to know what I'm wasting my money on and whats worth buying.

I'm looking at the stronglights which is the only reason I'm going isis, just in case you were wondering. Thanks again.


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PostPosted: Thu Jun 09, 2005 3:24 am 
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Oh, stumpytrunks, you wanted an actual product recommendation and not just jive theory? ?? :)

Between the 2 FSA you mentioned I agree with nexusheli, if I read him right: the differences are pretty marginal and even the ti is not a real weight-saver part (@ 185g claimed a 14g claimed weight difference). I have one of those scandium New Ultimate/Token/etc. 118g + bolts ISIS variants: the first self-destructed after 50 miles, the second (replacement) has been fine so far.

For the negligible weight difference, I'd probably just get the CrMo at almost half the price, see how it lasts and how you like ISIS. Either way, ti or CrMo, you'll be replacing it, it's not a forever part. I think, given the same basic design and bearing system, durability would be about equal.

What else is available in AUS to you? I've heard good things about RaceFace, and the top TruVativ bb can be spec'd with 4 bearing races as well, as I understand it. I hope that helps a bit.

Quote:
So you end up with unused space at the end of the shell, space I'd like to see used to make stiffer BB bearing assys.
Well, that's the MOST system, for instance, or its variants; it's a bb redesign, and generally exclusive, proprietary, non-universal, impractical. IMO it's a fairly unnecessary solution looking for a problem, like integrated headsets or, worse, the Ridley headset :roll: ...or, alternatively, one could pay Paragon, etc. around $500/$600 to machine a ti bb shell to accept an FSA MegaTech bb...for what, exactly? Oh yeah, more stiffness...I forgot. :wink:

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PostPosted: Thu Jun 09, 2005 3:49 am 
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Location: Tas, Aus
Because the exchange rate is so good at the moment (77us cents/dollar) and the fact that the stronglight cranks arent being imported here I thought I'd just go for a bit of a bulk deal in America. I was leaning towards the cromo spindle but just wanted to see if anything justified the extra cost of the ti. I'll have a look into those other options but with how the pricing is in Australia at the moment I'll be lucky to find anything half decent within 50 bucks of the cromo fsa. An examle of the huge price difference is the ritchey wcs stem at a rrp of $180. I think I saw a new one in a U.S.A shop the other day for $50 which is roughly $70 Australian. Absolute joke. I think I'd rather go for the cheaper slightly heavier option and get a lighter stem or post.

I know with isis that you cant really expect anything but how many miles/kilometres do you think Id get on average with a cromo?


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PostPosted: Thu Jun 09, 2005 11:11 am 
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Joined: Tue Mar 08, 2005 5:34 pm
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Location: USA
Quote:
I know with isis that you cant really expect anything but how many miles/kilometres do you think Id get on average with a cromo?


Regardless of Cromo or Ti spindle, the FSA Megaquads have the same bearings. Typical feedback I've been hearing has been a couple/3000 miles before "failure" which is sort of a subjective term. Anyone else heard different?


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