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Discussion Starter · #1 ·
I live in southeastern Wisconsin, which by and large is pretty flat, and I had started to max out the compact crank that came on my bike, so I started looking for a standard crank. I ended up getting a slightly-used standard shimano 105 5600 crank (with bottom bracket included) off ebay for $40. Not bad, considering you can still pay upwards of $150-200 for a new set of the same crank/BB.

Anyway, mission accomplished with the bigger chainrings. What I wasn't suspecting was the improved stiffness that came with upgrading from the square-taper spindle that was on there before to the outboard-bearing bottom bracket. I'm not a clydesdale by any means, so I was really surprised to be able to notice the difference in terms of power-transfer. Good stuff.
 

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Cause and effect

Oracle7775 said:
What I wasn't suspecting was the improved stiffness that came with upgrading from the square-taper spindle that was on there before to the outboard-bearing bottom bracket. I'm not a clydesdale by any means, so I was really surprised to be able to notice the difference in terms of power-transfer.
You're attributing this "feeling" totally to square taper vs. external bearings, but IF there was an effect, it was due to some design differences not really caused by the square taper vs. external bearings issue. Plus, you would most likely find that if you put a stopwatch on it, you wouldn't be able to reliably measure any difference in speed from this perceived difference in power transfer. Just saying.
 

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Oracle7775 said:
I was really surprised to be able to notice the difference in terms of power-transfer. Good stuff.
I'm afraid I have to agree with the previous poster on that. Unless you did a number of precisely timed runs under controlled conditions, your "power transfer" difference is pretty much in your head. But even if it is, it's not all bad: a placebo effect can motivate you to ride a little harder than you normally would.
 

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Discussion Starter · #4 ·
You guys make me laugh. Coming from my MTB background, I forget how particular roadies are with their terms! I probably shouldn't have used the phrase "power transfer," or at the least I shouldn't have posted about it until I had conducted "a number of precisely timed runs under controlled conditions," as wim suggests, and then written up a thesis with all sorts of colorful graphs. I am duly humbled!

It just felt stiffer, that's all I was trying to convey.
 

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What was your previous crank? Only time I felt the difference in swapping cranks was when I went to a cheap-o Suntour crank to FC-M530 Deore.
 

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Discussion Starter · #8 ·
Previous crank/bb was an FSA Vero 50/34 172.5mm, which uses a square taper spindle. I suppose the increased stiffness (huh huh, he said stiffness) could have come from the higher quality crankset itself.

I noticed a similar difference, although not as pronounced, when I went from the octalink 2004 Deore LX crankset to the outboard bearing BB 2008 Hone crankset on my MTB. In that case, I was pretty sure it was the difference in the BB's that created the sense of increased stiffness, as the cranks themselves were pretty similar in terms of weight, material and construction.
 
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