Crankset stiffness?
07-16-12 | 12:36 PM
#1
Thread Starter
Senior Member
Joined: May 2011
Posts: 1,421
Likes: 1
From: NoVA
Bikes: Specialized Allez Sport
Crankset stiffness?
When people talk about how one crankset is stiffer than another, what are we talking about here? Crankarms? Chainrings? Being a weak and mortal, I surely can't tell the difference between one to the next beside the total weigh so please elucidate me.
07-16-12 | 12:43 PM
#2
Throw the stick!!!!
Joined: Apr 2003
Posts: 18,150
Likes: 93
From: Charleston, WV
Bikes: GMC Denali
I have had quite a few bikes and quite a few cranksets. I have yet to notice a crank flex. I'm a firm believer that the frame / bb is going to flex enough to hide any crank flex I get.
I remember an article in a bicycling magazine a few years back testing cranks. The difference of flex from best to worst was in fractions of a mm. They even stated it wasn't nearly enough for anyone to ever notice.
I remember an article in a bicycling magazine a few years back testing cranks. The difference of flex from best to worst was in fractions of a mm. They even stated it wasn't nearly enough for anyone to ever notice.
__________________
I may be fat but I'm slow enough to make up for it.
07-16-12 | 01:08 PM
#4
Cat Enthusiast
Joined: Aug 2011
Posts: 2,227
Likes: 0
From: Plymouth, MI
Bikes: All City Nature Boy
Crank flex is not an absurd thing to occur. On one of my fixed gears, I had 3-4mm of clearance between the end of the crank arm and the drive side chainstay. At some point, I flexed it enough to knock the paint off in that spot. It was a higher-end crankset on a very stiff aluminum frame, but I'm a fairly strong and heavy rider.
07-16-12 | 01:17 PM
#5
Full Member
Joined: Jun 2010
Posts: 447
Likes: 18
From: Seattle
Especially when you're considering the vector of the force being applied to the crank, crank plex seems like a pretty minimal thing. If I had to guess, what most people attribute to crank flex is probably BB flex.
07-16-12 | 02:09 PM
#7
New but not Noob
Joined: Jun 2012
Posts: 95
Likes: 0
From: Central Florida
Bikes: Madone Litespeed Paramount Colnago
You can flex them but it takes alot. The BB usually gives up first but either way, it takes a lot. I raced BMX alot and up until my 30s , where you do alot of standing starts and then literally torque the whole bike under you. I've twisted crank arms, BBs , pedal axles , bar stems ... pretty much you name it. But thats the price you pay if you ride the balance between strength and maximum light weight.
07-16-12 | 03:46 PM
#8
Senior Member
Joined: Mar 2010
Posts: 23,208
Likes: 10,653
From: Seattle, WA
I thought I felt the left crank arm (6700) flex once, going up a ~20 % grade, toward the end of a long day when I was tired and just wanted to get to the top. But I've never felt it again, so it was probably in my imagination.
07-16-12 | 06:24 PM
#9
pan y agua
Joined: Aug 2005
Posts: 31,812
Likes: 1,234
From: Jacksonville
Bikes: Willier Zero 7; Merlin Extralight; Calfee Dragonfly tandem, Calfee Adventure tandem; Cervelo P2; Motebecane Ti Fly 29er; Motebecanne Phantom Cross; Schwinn Paramount Track bike
Crankset stiffness?
Whether its the bb shell or the crank, there is definitely a difference with 10 speed external bearing cranks and the older internal bearing
Cranks
I can induce chain rub and. Even throw a chain on 9 speed and older cranks
. Never done that with new stuff either shimano or Fsa
Cranks
I can induce chain rub and. Even throw a chain on 9 speed and older cranks
. Never done that with new stuff either shimano or Fsa
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
