Q Factor and my search for Long Cranks (175mm)

I’m in search of ISIS cranks longer than the KH 165 Moments.

I found anumber of potential cranks, all trials stuff, but the Q Factor is bigger than what I’m riding now, ranging from 25-35mm. Anyone riding high Q cranks?

Moments are 10mm
K1 and QU-AX are 0mm

Anyone have ideas, sources for low Q cranks that are long?

I’m wanting 175’s for my Surly Larry, might try 170’s though that’s not relaly enough to make a difference.

QuAx made a 170 ISIS chromoly cranks, but I can’t find a source for them, anyone?

man sorry but , whats is Q factor?

Q factor is how offset the pedal is from the spindle. Unis don’t have chainrings and stays to clear, so they have a lower Q, whereas bikes need a bigger Q to keep from hitting the frame. A longer spindle helps reduce Q.

So, anyone have ideas?

I spoke with Josh at UDC and he said that if I wasn’t going totally agro, that the basic aluminum QuAx cranks in a 170 would probably be fine AND they just so happen to be on sale for $10 a set :astonished:

I bough four pair :slight_smile:

Still looking for stronger options, for instance if anyone is running bike trials cranks, which ones do you have and how does the extra Q ride?

I have a pair 160mm Echo SL cranks. I haven’t seen any specs on the offset but if it’s higher than the offset on my Moment cranks, I never noticed it.

I have a pair 160mm Echo SL cranks. I haven’t seen any specs on the offset but if it’s higher than the offset on my Moment cranks, I never noticed it.

I definitely notice the difference in offset between my Nimbus Ventures, which have very little offset, and the Echo/Moments though. I prefer the offset of the Echo and Moment cranks for muni as I find the slightly wider stance make me feel more stable.

There are a few makes of tandem cranks that are available in ISIS, so you could get a left and right crank with no spider. Possibly a bit of an expensive though. These for example (although those particular ones may be no stronger than the QuAx cranks). Not sure what the offset is, but I don’t think most bike cranks have as much as the 25-35mm you mentioned.

BTW - (being pedantic), Q is the distance between the outsides of the cranks (or insides of the pedals). Crank offset affects Q, but it’s not the same thing. A longer axle increases Q, not reduces it.

Big Q makes for more wobble at high rpm, but if you’re using 175s on a giant tyre that may not matter. It also makes for better manoeuvrability, which may be a good thing with the massive tyre.


Big Crank

I’m wanting 175’s for my Surly Larry, might try 170’s though that’s not relaly enough to make a difference.

I’m using 180mm PRIMO crancks on my Muni. offset (Q) is low at 10. Remember,-Size makes a difference. Not fast but climbs well.

The Sinz cranks seem to have the same Q as KH Moments you can find them online for about $60 in sizes up to 180mm. It does have a spider on the RH crank which you could grind off if you wanted.

And 5mm can and does make a difference.

These are what I was considering:

Mfg reported 35mm Q factor.

If they are using the Q measurement correctly it would equal 17.5mm offset/side. If the KH cranks have a 10mm offset that would be 20mm’s of additional Q. This puts the Trialtech arms quite a bit wider, but not as much as it first seems.

To make things more interesting it looks like on the KH site they list the cranks with a “10mm Q Factor.” I don’t know who started using the term incorrectly, but until we are all speaking the same language the only thing we know for sure is that all of these cranks have some offset.

Maybe we should start measuring them.


I tried to get an idea of how the Q is measured, received an email from Trialtec where they show on a diagram the Q being measure from the inside of the crank arm at the pedal threads to the inside of the crank arm at the spindle, that measurement being 35mm. When I measured my Moments in the same fashion I got 10mm.

What would be really great is if someone had some trials cranks and could take a picture of them side by side with some uni cranks.

Anyone? David? Saskatechwan?

I could dig out my Echo cranks but the only other ISIS cranks I have that are not mounted at the moment are short QU-AX ones so I don’t think it would be a very good comparison.

At one point I put them on facing the same way and measured the distance from the outsides of the pedal holes and they were about 5mm wider than Moments. This makes me think they have 2.5mm more offset on each side so 12.5mm offset.

Since the Q factor started getting wider as mountain bikes got wider tires, and shorter stays I would say that using any crank made for a bike with short stays, and wide tires will have considerable Q. Since ISIS came into being fairly late in the game it means that most ISIS cranks will be designed for frames like I described above.

A good option may be to get a pair of ISIS BMX cranks. BMX racing bikes generally have fairly narrow tires, and relatively long stays. Also, they are designed to be single speed so they don’t need room for multiple chainwheels, and derailleurs.

Why not get a pair of FSA Carbon Pro BMX arms in 175? That would be a pretty sweet setup on your Ti frame. They have an aluminum spider that is probably just bolted on, so should be easily removable. I can’t find any info on the Q, so it may not be any better than what you’re finding.

Got some cranks from UDC: QuAx 170’s

These are the less expensive cast cranks that UDC was selling as OEM on their Nimbus unis until they built the Voyageurs.

Though not the strongest cranks, they are much lighter than the Moments and according to Josh, they are strong enough for light muni.

Since I don’t do big drops, I figured they were worth a shot, esp with them being on sale :slight_smile:

So far I have ridden my Larry equipped Surly three times with the 170’s and have had not problems with loosening, bending, etc…

The difference between 165’s and 170’s is amazing, who would have though 5mm could make such a difference!

Photo of  in Saskatoon, Saskatchewan, Canada.

i herd this guy is really good. hes based in saskatoon canada and sellis echo parts. dunno what the q factor is. i know he had 170s…not sure what he still has left sign up to pinkbike.com and pm him hes pretty quick to respond.

Those are Echo Cranks, got to see a pair of those up close and personal, relaly nice cranks, light, but the Q factor is way too much for uni.

Word on the street is that Nimbus is gonna make something longer…

In the meantime, 170’s by Qu Ax are about as long as muni cranks come unless you go to Profile which seem to be on the down and out.

I compared the offset on a pair of Echo SL cranks and Moments and the Echoes have an extra 5-6mm of offset per side so 10-12mm of additional Q. They go further onto the axle than Moments so they require thinner spacers.