[Closed] Q factors

I'd love to know this aswell...trying to reduce my Q factor to a minimum...if poss or save up and buy a Cannondale BB30 equipped bike

you are right reluctant

My 113 bb equiped middleburn set up was 7 inches Q factor - my XT hollowtech chainset is 8 inchs - my fixie was 6 inches and my roadie was 6.5inches

But it turned out not to be my issue in the end thankfully.

2 methods i looked at to reduce q factor were

1. run an XTR chain set

2. run a ultegra road compact double Chainset

Both possible and both working well on people i knows MTBS

Never seen a table of it, but - and as one not usually sensitive to fine details - hopping off an XT HTII bike and onto an XT square taper 68x110 set-up was a shock, a much lower Q and (following cleat tweaking) way more clearance between shoe/ankle and crank. Very nice!

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

it has a small list ,,

🙂

Never seen a table of it, but - and as one not usually sensitive to fine details - hopping off an XT HTII bike and onto an XT square taper 68x110 set-up was a shock, a much lower Q and (following cleat tweaking) way more clearance between shoe/ankle and crank. Very nice!

Interesting to hear that - I had never really thought about that before but now it becomes clear...
I have a few MTB's all Shimano HT of one type or another but also ride a roadbike with old Dura-Ace 9 spd (cartridge type BB) and I always had the feeling that my cleats weren't right. (they were under enough side tension to feel but not enough to click out). This would explain a lot..
Will measure it this evening now...

http://forums.mtbr.com/showthread.php?p=2919387#poststop

People on Weight Weenies talk about it quite a lot.

Crank Brothers do short spindles for Egg Beaters, easy way to reduce q-factor.

There's an increasing number of MTB double chainsets out there, all with lower q-factors:

FSA K-Force SL
Extralite E-Bones
THM Clavicula DP

As well as all the BB30 set ups.

What are pros/cons of wide/narrow Q factors?

Well theoretically you want to get a q-factor that mimics your natural stance as closely as possible.

For some people this is actually not that narrow, particularly women who tend to have wider hips. Indeed Look do a Keo Womens pedal with wider q-factor.

I could do with a narrower q-factor as I have a significant shoe/crank interface problem with HT11!

I just measured those a couple of days ago on various cranks/frames, not the actual Q-factor but the distance between the inside of the crank arms if they were parallel and also the distance between the outside of the chainstays 175mm behind the BB to check clearance. I did this because I want to re-shuffle some cranks from one bike to another..., and of course I don't have the numbers on me right now. Anyway, a new Shimano 105 HTII double ring setup was certainly the narrowest, still giving quite some clearance on an On-one Scandal frame, but not much (maybe 1mm) on a very old Serotta steel MTB frame. A 3 year old Race Face HTII crankset was the widest, and the two square taper in between, but that obviously depends on spindle length.
Clearance of the cranks is not the only problem as the small chainring on a triple setup might scratch the chainstays even though the cranks have enough clearnce against the chainstays.