Q Factor

So, my new jump bike has Profile cranks with spacers either side, the drive side spacing arrangement is determined by the size of the chainring in relation to the stay but the non-drive side is only determined by crank arm in relation to the stay.

This has allowed me to have the cranks at different lengths from the centre of the BB, the non-drive side is about 3mm further in towards the BB.

Is this gonna have any detrimental effect? I figured not as it's a toy bike and I'll hardly be cranking any miles on it.

Thanks in advancings good people of LFGSS.

D

nope

for efficiency the narrower the better (depending on your physiology) a lot of the time trial bikes used in the tour of britain were running old dura-ace for it's narrower q-factor.
for a tosspot bike it will not matter.

Thought so, momentary moment of momentum related mentalness.

Murtle, come and bleed my bloody brakes!

busy

Not now I'm in my pants. Saturday mornings???

no, now, please !!!!

actually i have just left

turns off lights and locks doors

turns off lights and lights candles, puts on murtle's favourite dress and stockings

.

YouTube - Fear Factor Haircut

:d

I was thinking about Q factor today as I studied my crankset.
Since most track cranks tend to aim for the same low Q Factor, do people adjust their pedal spindle length to optimise power output/ comfort etc?
or is this not widely available/ worth thinking about?

ta.

if you do, it will put your chainline out

if you do, it will put your chainline out

in what way?
you're not touching the BB axle length, which is the only thing to affect your chainline crankwise.

Pedal spindle lengths:
just pushes foot further out.

ah, sorry. didn't read it properly.
i suppose some pedals will put your feet nearer the crank arms. mines only about 5mm away, and if you twist your foot a bit it will rub on the cranks.

I was just wondering really, no desire to actually try and change much.
I've got a bunch of different pedals to try out on the track.
used to riding SPD SLs so got some SPD Rs, and some LOOK etc....
the SPD Rs have a much more, apparently, longer spindle than the SLs.
seemed odd to me.

Dura ace spd sls will reduce your q factor compared to 105 level pedals, but there is a limit how low you can go without rubbing your toes against the cranks.

With all the shoes and pedals I tried, I was able to set the cleats up in such a way that my feet were rubbing the crank arms.
I cannot imagine that the pedals or the length of their axles can influence the Q factor. Or the axles must be extremely long, so long that it cannot be compensated be the adjustmen of the cleats.
Don't think that pedals have any influence on Q factor.
IMHO it's just about frame, BB axle and crank arms.

well, a pedal with a longer axle means the q factor can be increased thus influencing the q factor shirely?

It was generally the width of the cranks that indicated q-factor
http://www.sheldonbrown.com/cranks.html#tread

BUT..

Time Impact pedals have adjustable Q-Factor. According to their website (http://www.timesportusa.com/impact_technology.html):
"Q-factor adjustment.
IMPACT allows adjustment of lateral foot position. This setting makes it possible to move your foot 2.5 mm closer to the crank. Depending on the Q-factor setting, lateral float can range from 5.0 to 2.5 mm."

and

The "Q factor"
This is the measurement between the pedal mounting surfaces (outside surface) on the crankarms (and indirectly the distance between the midline of each foot - which translates all the way up to the knees and hips.) The easiest way to determine Q-factor is to remove one crankarm and mount it in-line (not at the 180 degree rotation you use with riding) with the other, then measure the distance between the outside faces of the arms.

Another aspect is the distance between the crankarm and the pedal platform itself. You need more clearance there if your ankle bone hits the crankarm, if you purchase wider shoes or if your winter booties rub the crankarm. You may feel more comfortable with your feet in an outward position (though a few riders prefer the opposite.) The ability to fine-tune Q-factor means that you can make two bikes match, such as your mountain and road bikes. Mountain bikes typically have a significantly wider Q- factor.

Some pricey pedals allow you to adjust the location of the pedal platform and thus the perceived "Q factor", but there are much less costly ways to do so. If you need only a couple of millimeters additional clearance, get a spark-plug washer at an auto-parts store and simply slip it over the pedal axle before you thread it into the crankarm. Depending on the length of the threaded portion, you may be able to use two or three washers for greater spacing. Make sure there's at least half an inch of thread on the pedal shaft in the crankarm.

Is this a big deal for riders? Plenty of serious riders who train and race on road bikes and mountain bikes experience two different Q-factors without problems. So I'd adjust for what feels right for you.

and..

http://www.recumbents.com/WISIL/qfactor/qfactor.htm

BLACK HAWK DOWN BLACK HAWK DOWN
Jeebus don't do that to me any more, OK? We'm be old an frail my son

Recently bought a 2nd hand ribble as a winter bike and it came with a triple chainset. I wouldn't have normally chosen a triple but thought it would be fine for just getting the miles in. Now I notice that my feet feel noticeably wider apart when clipped in. I'd never even thought about Q factor when fitting myself to a bike, but now am wondering if it's the reason I'm having difficulty getting my position sorted. Can q factor have such a significant effect?

Do all octalink cranks have a stupidly wide q factor? I've just measured some up and between the outside crank faces it's 188mm on a 121mm bottom bracket. The narrowest Octalink BB I can find is 113mm, which would give 180mm, which is still quite wide. I've just measured up various bikes and they range from about 145mm for road bikes up to about 178mm for hybrid/dadbikes, so it's beyond any of those.

I used to have some octalink cranks with a 109.5mm BB
Otherwise can't help sorry