Still trying to reduce the q factor on my Pugsley because of knee trouble. I want to run square taper ideally but can't find much about , old or new which would do the job . I noticed a lot of older road/touring chainsets from decades ago had parallel cranks ie the crank arm did not flare out and stayed parallel to the chainrings ,thereby giving a low q factor ,but not sure whether they would work or are compatible with smaller rings as found in 1 X systems ( 32, 34 etc ).
I am also about to try time atac clipless to give some float as I was running spiky flats with 5 Ten shoes (which may have locked the feet into the wider stance and hence irritated the knees ).
I have seen a few folk have shaved the bottom bracket shell and fitted 89mm bottom brackets with carefully selected cranks but it would appear quite expensive and obviously involve irreversible surgery.
If anyone knows of any other solution, chainset etc I would appreciate suggestions.
Yours hopefully
Bill
The limiting factor on QFactor is will the cranks clear the chainstays or will a lower Q factor hit the chainstays.
Straight cranks and comparable nonstraight cranks will have the same Q factor. The straight cranks will have a slightly longer axle and the nonstraight cranks will have a slightly shorter axle.
Get a different frame to allow a lower Q factor.
As above, whether the cranks are parallel/straight or flared out is not a good indicator as the BB width and chainset design (depth of spider) is also a factor.
Frame is the limiting factor, on all my modern bikes the cranks are probably within 5mm of the chainstays, going from 175mm cranks to say 165mm may allow a smidge reduction in Q factor.
However, going from big old flats to Time or similar probably will reduce Q factor.
Do you know this is the source of knee pain? Often it can be fixed with insoles in the shoes or wedges under cleats, correcting saddle height and fore/aft position, or just seeing a physio. My wife had knee pain but since a physio gave her some simple leg exercises using a big rubber band she has not suffered with it, I think the muscles on the inside of her leg were stronger than the outside so this caused the knee cap to twist.
I don't think I'd switch to clipless until you've covered bike fit/shoe fit/physio bases to confirm the cause of pain, normally people switch the other way with knee pain.
Took me a while to realize that actually spiky flats with grippy soles give no float at all and so may well be more problematic for the knees than clipless with a decent amount of float hence my up and coming experiment ..flats to Time atacs . We shall see and I'll report back . As for saying get another frame ..there are virtually no fatbikes with very low q factors ,for obvious reasons..hence the problem. A crank with lower q factor will work and has been done already on the Pugsley it's just that it involved a fairly expensive set of cranks and shaving the bottom bracket.
He ended up with 184 Q factor ..mine is currently over 200 and many cranksets for 100mm bb's are even wider.I appreciate all the suggestions though and it may well be more than the increase in Q factor (compared to my normal bike) that is causing the issue but little else has changed.
well ...I am pleased to report I managed to find an old stronglight square taper chainset which ..together with one of my 100mm ST bb's ( I had 3 different lengths bought cheaply to try ) has given me a greatly reduced Q factor and hopefully solved the knee pain as a result . I can only run 1 chainring but have no heel rub or chain tyre rub in the lowest gears even running a 4.8 tyre ( 65mm rim) which many said wasn't doable on the older Pugsley . The chainline is also close to original . The crank may not win any awards for stiffness/bling or fashion but pedals great and I'm at an age where such things are of little importance . Pretty pleased really as the only way to get such a reduced Q factor on a fatbike was said to be either to modify the frame or to buy custom / waltworks etc which isn't exactly cheap .
Guess my Q factor is around 186/7mm now ...whereas on many modern mtb's with 73mm bb's it's often 175 or even more.... so not a huge increase and it means I can now enjoy fat whereas I had come to the conclusion 29plus would be the limit .
