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PostPosted: Tue Sep 17, 2013 5:04 pm 

Joined: Tue Jun 07, 2005 3:32 pm
Posts: 551
Does it mean much? I suppose it's something.

My main query is: is it just me, or did they get the weights wrong, and now they're stuck with it?
My thinking is, is that they use way too little weight on the BB, and too much weight on the wheels. Like, they get BB deflections of about 0.3mm (or thereabouts), and up to 10mm for rear carbon wheels.

For those who don't know what I'm talking about, they put each tested frame in this jig, "apply" (I'm not exactly sure how) 40kg to a crank, and measure the deflection at the BB, head tube and seat tube junctions



PostPosted: Tue Sep 17, 2013 11:23 pm 

Joined: Mon Mar 18, 2013 3:45 am
Posts: 164
I have quoted below a great explanation from Ride about the Jig test. It is usually used to give an indication of where a bike may lie on the stiffness and ride scale, ie. all out race bike, all rounder, comfort bike etc. As mentioned below the results are only really comparable to each other and may have no indication of how it rides in the real world.

"The test jig measures deflection of three frame points under a load applied via the crank arm. Basically, because it is a static test, it’s a ‘snapshot’ of how stiff the frame is. It is also an empirical test, ie. measurements gained from our jig tests are comparable only to each other. For instance, if the bottom bracket on bike ‘A’ deflects greater than bike ‘B’, we can only say that ‘A’ deflects more than ‘B’. We cannot say outright that ‘A’ will be any less stiff to ride than bike ‘B’ because frame dynamics are not accounted for.
The three fields of information presented are: the bottom bracket junction; head tube and top tube junction; and seat tube and top tube junction. Generally the lower the reading, the less the frame deflects. This would lead us to believe that the frame is laterally stiff (this property is mostly noted when riding).
Other points to note: 1. The weights are butted against the steel rod at a point which correlates to the average cleat centre of every pedal system on the market. 2. The bike is anchored at the fork and frame dropouts, via nutted axles. 3. We use calibrated Kincrome analogue gauges that measure to 0.01mm deflection."

PostPosted: Sun Sep 22, 2013 1:48 pm 

Joined: Tue Jun 07, 2005 3:32 pm
Posts: 551

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