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Cannondale ad - measuring bottom bracket stiffness(6 posts)

Cannondale ad - measuring bottom bracket stiffnessNessism
Mar 6, 2003 9:56 PM
Just saw the Cannondale print ad where they test the bottom bracket stiffness of several high end frames including a Litespeed Vortex, Colnago C40, OCLV, and Cannondale CAAD7. Quite interesting to me, particularly reagarding how the Vortex and C40, which are often lauded on this board for their stiffness, were a fair a bit more flexable though the bottom bracket than the CAAD7 and OCLV frame. I'm not convinced that extra bottom bracket stiffness leads to a faster frame. But for those that like the feel of a stiff bottom bracket, the numbers don't lie.

Too bad they didn't publish more data on some other frames. I'd love to see how different Ti frames test out compared to one another.

Ed
lets go a bit furtherFunston
Mar 6, 2003 10:28 PM
yeah it sounds interesting. I'd like to see the same test done on compacts vs. traditional frames. Also on different size framsets. Let's see more of these tests, more often.
where is the article located?nmwheelsucker
Mar 7, 2003 6:00 AM
..back cover of CycleSport from last fall...nmSpunout
Mar 7, 2003 7:03 AM
Interresting discrepancy with other measurementsStampertje
Mar 7, 2003 8:53 AM
Dutch cycling magazine Fiets do stiffness measurements as a part of their monthly bike reviews, and the CAAD frams consistently come out on the lower end of the scale. They quote bracket stiffness values of:
CAAD4 48.1
CAAD5 40.7
CAAD6 40.2
CAAD7 45.5
C40: 48.5
C40 B-Stay: 51.3
CT1: 47.6
Colnago Dream: 64.9
OCLV 5200 (2000): 48.8
OCLV US Postal (2002): 45.7
Giant TCR Carbon (2002): 53.5
Klein Quantum (2002): 57.1
Merlin (model not specified): 53.5
Raleigh 853 (1996): 55.6 (so much for flexy steel)
Specialized Comp A&S (2002): 34.1 (so much for stiff aluminium)
Higher is stiffer, I don't know what the units are (mm/10kN or something like that, I imagine). They consider 50-60 to be the optimal range. The stiffness is measured as the deflection under a applied (known) force, but the exact method is not given on the website.

Numbers only tell you so much; they'll admit so themselves (especially when frames from favourite manufacturers end up at the ends of the scale). If you read Dutch, you can find the values at their URL, under "Stijfheidsmetingen". Torsion/lateral stiffness = torsiestijfheid, fork stiffness = vorkstijfheid, bracket stiffness = bracketstijfheid, consistently misspelled "bracketstijhheid" on the site :)
You are quoting am advertisment which is not exactlyLazywriter
Mar 7, 2003 7:26 PM
an objective source. Also, this topic came up before on another site and you cannot factor out the differences in the what components were used. If they did the test with identical bottom brackets and cranks, then the measurements would be more accurate, but C' Dale used their proprietary bba dn crank versus Dura Ace on teh other bikes which factor into equation. Plus the difference in deflection was so small that there is no way on earth this difference would be felt. Why don;t you just go watch an infomercial and sit gazed in amazemetn while you are at it. Ridiculous to quote an advertisement as an objective piece of info. LMAO