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q-factor: why minimize it?(6 posts)

q-factor: why minimize it?weiwentg
Jan 24, 2003 5:27 PM
I know what q-factor is. but I'd like a biomechanical explanation of why it's good to minimize it. we've already heard explanations of why people try to minimize pedal stack height, so let's have at q-factor.
It's all about proportionKerry Irons
Jan 24, 2003 7:26 PM
For many people, their hips are narrower than the pedal spacing on the bike. Not everyone, but many. Plus, for a while 20 years ago, there was not much attention paid to this and some cranks got pretty wide. Lots of people felt like their legs were no longer straight up and down, but rather splayed off to the sides. Not a good deal when you want all your pedaling force to be straight down and you want your joints to align. There's also a slight aero advantage by having your legs a little closer to the frame. Some people say that wide cranks bother them, others say they can't tell the difference, and then (of course!) there are some that say they like wider cranks.
Have you ever used a gym bike (e.g. lifecycle)....Bruno S
Jan 24, 2003 8:24 PM
the pedals are spread very wide. Its very unconfortable and feels harder to pedal. These bikes with large q-factors feel weird.
Have you ever used a modern mountain bike?Ray Sachs
Jan 25, 2003 3:50 AM
With the wider rear dropout spacing (135, compared to 130 for modern road and 126 for older road bikes) and the wider chainstays needed to clear really fat tires, Q factor gets huge. I ride a cross bike with a low Q off road these days - my knees couldn't handle the Q on the full suspension mtb I used to have. I use Ritchey double cranks on my road bikes which have a Q of about 140mm, compared to lots of road cranks in the 160s and mtb cranks wider than that. It also makes the bike harder to control when rocking it out of the saddle - I think part of the move to wider handlebars is to compensate for that and regain the leverege that was lost.

It's all personal preference though - as noted above some folks don't care and others prefer wider cranks.

Go for a walk in the snow.Spoke Wrench
Jan 25, 2003 5:32 AM
I questioned the concept that narrow Q's were better a while back. Then I looked at the footprints that I left while walking in the snow. My heels almost touch. This makes me assume that my natural body geometry prefers to have my feet closer together. I think that narrow Q's are better.
re: q-factor: why minimize it?Ian
Jan 25, 2003 8:06 AM
You do not necessarily want to minimize it, some people may want to widen it. Ideally, you want your legs to run in straight line directly down from your hips. Let's take someone like Tyler Hamilton who is around 5'6", weighs about 140lbs, and probably has around a 28 inch waist. He has a very small bone structure and would probably prefer the smallest / lowest q-factor available. Then let's take someone who is not a professional cyclist, maybe 6' even, weighs a muscular 190lbs, and has a 33 inch waist. He may want his legs / feet a bit further apart than someone of Tyler's size.

Of course, keep in mind this is certainly not a hard and fast rule. It is much like crank length, 99.9% of the riding population would not notice if someone secretly switched out their cranks for ones that were +/- 2.5 mm of their current set-up. And that same percentage would not notice if you moved their q-factor +/- 1 mm.

It is all about the "ideal" position. But people are so different, that two of exactly the same proportions could prefer two different things.