79pmooney

My knees really like small Q-factors. (Chronromalacia patellae for the past 45 years. Keeping those knees happy is a matter of them or replacements.) My bikes over the years are all become either fix gears where low Q-factor is easy to do or triples. But the Q-factor on my geared bikes keeps getting worse, or at least did until I started going out of my way to reduce it. This seems to be a trend promoted by Shimano. Their influence is such that everybody else falls in line.

I set the TiCycles frame I had made 11 years ago with a Shimano Hollowtech 105 splined triple crankset. Sweet! Light, stiff. Made to go forever. And the biggest Q-factor my knees have ever seen. I started noticing my knees tended to be happier on my fix gears!

Two years ago I set my Mooney up fix gear using an old Sugino crankset as a triple using 1/8" chainrings, chain and cogs. Used an old Sugino crankset Now the inside boltholes for the 74 BCD chainring were useless as I was never going to see 1/8" rings to fit them, so I mounted the inner chainring on the normal inner double spot, the middle on the normal outer double spot and the third chaining cantilevered out close to the crank arm. (No front derailleur so all it had to do was miss the chain.) I set this up on a Shimano BB, measured accurately how far in I could move both cranks before hitting the chainstays and ordered a Phil Wood BB from the factory. (Turned out a stock symmetrical 105mm would do just fine.) Inside chainring is VERY close to the chainstay and the left crank misses by an amount I haven't seen since I raced decades ago. (My knees love it!)

This spring I re-did the Mooney as a gravel bike; back to a triple but now a 50-38-24, lowest I've ever used. Fun! Specialized old-school straight cranks (probably made by SR; similar to Sugino but the little details re different). But I went back to the fix gear after having it clearly shown to me that my gravel days are past; not something someone with what I call "loose brain syndrome" should be doing. (I made that term up but any NFL guard would know exactly what I am talking about.) So I had this sweet crankset lying around.

Well ... that sweet ti bike was falling out of favor. My knees. Also I'm aging. 53-42-28 isn't working so well, especially with the 12-23 9-speed cassette I love so much. But ... that unused triple. Put it on using a 118.5 square taper Shimano BB I had. Nice, but the cranks sat way out on both sides. A full cog too far outboard and missed the left chainstay by roughly a library book. So I measured the misses. Ordered another Phil Wood BB, 105 mm 2mm offset. It is so close it took me a bunch of tries to dial it in. I've done real damage to paint, heard the click of the left crank hitting but I finally got it. All clear. No room to spare on either side. Middle ring sits just inside the middle cog. And the Q-factor ... 139mm! So last night I measured up my 4 assembled bikes for Q-factor

TiCycles 139
Mooney as triple fix gear 135
Trek (winter/rain/city fix gear) 137
Raleigh Competition (Sugino triple with Shimano BB) 164
Custom fix gear (currently not assembled but runs a Sugino 75 crankset on a Miche track BB. Probably less than 140)

Obviously that Competition is the next project.

And a comment/question re current "standards" - why are Q-factors so high? I know it makes design brain-dead easy. But for a lot of us, our knees are not meant to be bowed out. Why do cranks miss the chain by more than 3 mm? That 's plenty. Why are BBs for large offset cranksets symmetrical? My knees don't care that my feet are a cm to the right. They do care about every cm they get forced beyond where my feet would land without a bike forcing them apart. And ... increasing Q-factor is easy. Wider BB. Symmetrical BB. Pedal extenders. But reducing BB is a real challenge. Cost me a BB close to $200 and finding a crankset made 25? years ago. (Perspective - those BBs cost ~ one PT visit. For the deductible on knee replacements I can go Phil on all my bike the rest of my life.)

Ben (celebrating the little "q")

HTupolev

Crank manufacturers are trying to accommodate wide variations in frames.That's especially relevant with modern 2-piece cranks, since adding spindle lengths would create too many crank permutations.

Also, I suspect that indexed front shifting costs a millimeter or two between the outer ring and the crank arm. The FD cages are often pretty wide, and you can't get away with cheesy adjustments like you can with friction. I haven't done any precise measurements, but I've eyeballed a few cranks with calipers, and it seems like the modern 11-speed stuff usually leaves a hair more room than stuff from 40 years ago.

I have no idea why purported "road" triples are so wide, though. Even in the worst case - if you add the third chainring 5mm outboard of the big ring on a double, and then also widen the NDS by 5mm - you'd think that Shimano road triples would be around 156mm. Realistically, it should be smaller than that. But it's actually bigger.

I think the designers just don't realize that it's not much of a problem.

JohnDThompson 

Many modern cranks have curved arms to increase chainstay clearance on frames designed for wide (10+ cog) rear clusters. Older cranks designed for use with 5-7 cog clusters have straight arms, which reduces the Q-factor.

The venerable TA "Cyclotouriste" crank has one of the lowest Q-factors made, but has been out of production (but still widely available on the used market) for many years. But getting a vintage crank to work with a modern, widely-spaced frame may be problematic. You may need to compromise in some respect, either accepting a wider than ideal Q-factor to use a modern 10+ cog frame, or finding a vintage frame that allows you to use a narrow Q-factor vintage crank with fewer cogs in the rear cluster.

HTupolev

There's a 4mm difference between a 6-speed OLD and an 11-speed OLD. Even if we expand that to 9mm for disc or MTB spacing, it doesn't explain why an FC-4703 is 17mm wider than the stock triple on my 1979 Fuji America.

JohnDThompson 

Non-ferrous chainstays tend to be wider diameter than vintage steel chainstays, and further reduce crankarm clearance.

Eggman84

Space for wider tires, shorter chainstays, wider cassettes, and reduced manufacturing costs with 2 piece cranks. Some frames even are using a "dropped" drive side chainstay. But not to worry, triples are going out of style/availability so just use a compact double, with lower Q factor.

shelbyfv

I wonder why some people are especially sensitive to Q? Prior knee injury maybe? I see it discussed on the internet but never among the folks I ride with. I used to ride a couple of Shimano triples but never noticed they were any different from the doubles Ignorance is bliss?

Trakhak

Don't remember anyone complaining about Q factor until diatribes on the topic began appearing over and over again in the Rivendell Reader. Pedersen may have invented the term, for all I know. (He also claims that wider handlebars "open the chest" and permit easier breathing---pity the poor world-class time-trialists who ride with their elbows practically touching.)

Like shelbfv above, I never notice the width of my double and triple cranks. However, the pedals on my Campy Record-equipped Peugeot track bike feel weirdly close together on the rare occasions that I ride that bike, though I get used to it after a while.

Road Fan

I share your preference for low Q, though I can't say my knees are squawking as badly as yours are. I would not like the 164 mm Q on your Competition. At the moment I'm putting a Centaur double on my Mondonico with Q = 145, and one bike has a first-generation Chorus with Q about 139 mm. A Campy Racing Triple will come out more like your Sugino - same for the TA Aline triple that has been floating in my chainset box.

I would try to make a triple out of a modern TA Cyclotourist. Probably a modern genuine TA would get narrower than a V-O similar model, and certainly better than an IRD Defiant. Another good candidate would be a Rene Herse chainset in triple setup. I would also not be afraid to try a BB one step narrower in the Shimano spectrum when you find you don't like how it fits, remaining mindful of rear chainline and chain angularity. With any of these narrow ones I would move the chainset in toward the frame, keeping the left-right balance the same and implementing the correct 43.5 or 42.5 mm front chainline. I might compromise it up to 1.5 mm, but not much more. I'm finding a problem now with my Terraferma with a chainline mismatch of just a few mm. Within those limits you also have to watch for the chainring bolts, chainring support arms, chainrings and crank arm ends hitting the chainstays. Depending on frame flex, you have to judge how narrow you should try to get. You don't want the chainset sawing a hole in your chainstay tubing.

I think (educated guessing?) high Q's came from MTBs and moved into hybrid bikes, which seemed initially to just take advantage of wide-range MTB technology and existing products. I think when MTB first moved to multi-speed, low-Q was a thing but not a big thing. MTBs had wider OLD to enable wide cassettes, wide tires, and reduced rear-wheel dish. These features made chainlines move out to 47 or 48 mm, and wider crank arm positioning to clear the chainstays.

79pmooney

I raced a 1976 Sugino Mighty Comp double. Straight cranks. Close to both chain and chainstay. Missed the skinny Cyclone FD by not much. Never measured the Q but it was close. My TA and Sugino BB'd triples after that weren't a lot wider. I never gave it a thought; just set my next bike up close to the last, aware since 1978 that I had chrondomalacia and my knees didn't like change. Never had a Shimano BB until I set up my good bike 11 years ago. Also never saw knee issues going from one bike to another (other than from fix gear riding and climbing). It was when I found myself choosing to ride the fix gear rather than the good bike, then noticing my knees were not happier with all the low gears that I started putting this together. (Never followed Rivendale.)

That my knees are sensitive to Q-factor might be related to them being just as sensitive to crank length. I ride only 175s. Rode a year on a sweet Campy 172.5 while riding two other 175 bikes. Not a good experiment. I know we cannot possibly feel 2 1/5 millimeters with 890 mm legs. But I can feel my knees making my life miserable (and making it known they will not take it much longer).

Ben

delbiker1 

I do not even know what Q factor is, but I have changed the set up on my bikes to be friendlier to my knees and other body parts. I went with smaller chainrings and cassettes with higher tooth count cogs. I have a titanium Airborne Zeppelin that now has 50/38, 130 BCD rings, with a 12/27 cassette, 9 speed drivetrain. I think it is working out fine. I also have a Schwinn SS DBX, 110 BCD, that now has 46/34 rings, for which I purchased an 11/32 cassette, 9 speed drivetrain. I changed the 11t to a 12t. The cassette is installed on the wheel but I am waiting on a new Deore rear derailleur and used Tiagra brifters that have been ordered. This bike is set up as a errands/commuting bike with racks, HD wheels/spokes and wide tires, 32 to 37 mm. I am soon to be 67 and have really noticed the aging factor the last 1 and 1/2 years, more so than before, both physically and mentally. I am OK with that. I still ride at least as much, actually more the last 3 years, just not as fast and with more frequent stops.

Road Fan

Grant latched onto the tterm and used it, but I am pretty sure I recall it from the mid or early 1980s.

Eggman84

Whats the chance what you are experiencing isn't due in part to different gearing. Sure these bikes are geared differently, and we know too high a gear can place undue stress on the old knees.

79pmooney

My lowest possible gear on my custom fix gear is 42-24. The track standard 144 BCD allowing me a track standard narrow Q-factor and track quality round chainrings. (Yeah, the elves probably have a 41 tooth chainring stashed away somewhere but I have never actually seen one.) I've never seen or heard of an 1/8" cog bigger than 24 teeth. I can go lower on my Mooney as a fix gear if I bring a chainwhip which I have not done this year. The 36-21 regular lowest gear is almost exactly the 42-24 of my custom fix gear. The bikes my knees didn't like were set up 53-42-28 with at least a 12-23 in back and 52-42-28 witha 13-28. 28-23 is only ~70% of my lowest fix gear but my knees were not much happier. And on either fix gear, many hills get climbed on the 42-17 simply because I didn't stop.

Just came back from one of Portland area's tougher climbs. I didn't go hard (it was a test more of the bike than me), but I also never used my two lowest gears on the new setup on my TiCycles. (24-23 is the lowest. 24-19 was the lowest I used.) Laurel Road to Bald Peak Road in southern Washington County. Knees feel just fine. (I did make an improvement on my hot weather knee warmers so it was not a fair comparison but it was clear they liked both being warm (it was pretty hot; I often go bare knees when it's this warm) and the new low Q-factor. (Yeah, for scientific research, I should do just one change at a time but Cycle Oregon with its potentially huge knee challenges is coming up soon. Keeping my knees really happy is far more important to me. The $$s in for quality research is poor. The $$s out for overdoing it with these OEMs could be huge. Now, a big enough grant from the BF community might change my mind.)

Ben

79pmooney

Yes, new post because this is an entire topic change. (Still super-low Q but this is the mechanics.)

My Dura-Ace Triple FD doesn't go in far enough to shift onto the inner 24 tooth chainring now that I have moved that chainring inboard as far is it will go. Plenty of clearance on the inside in low gear once the chain is there, but I cannot get it to shift there. With the old SunTours, I used to take out the bushing on the screw at the bottom of the cage and replace it with a shorter stack of small washers. Well the D-A doesn't have the screw. The cage is bent into a wide "J" around the chain. So I had the thought "what if I added metal to the inside of the outer cage plate to push the chain off the middle ring?" Wrapped the outer ring with aluminum sheet metal. Shifted! Nicely. But self destructed as I knew it would after the chain quickly wore though the aluminum, then ripped it off. Still, point taken. Now, how to do it in steel? Well I made a piece that fits inside from the bottom of the "J" to just below where the chain sits in the highest gear. Taped it in place with packing tape and went for the ride in the post above. Wow! A joy. (But not for the world of index. On the middle and small chainrings, FD adjustment has to happen every few shifts in back. NBD for us DT folk.)

Next challenge - that packing tape is not the permanent solution. Will 3M Extreme double sided tape work? Picked some up and am going to try it. If that doesn't, I could drill two holes in the cage and drill and tap the steel piece. (For now I am using Home Depot 1/8' flat bar. On hand and easy to work.)

Does anybody know of a FD that works for triple, fits a 34 mm seat tube and travels far inboard? (Narrow cage or the ability to narrow it would be nice, both for quicker shifting and because the crank is pretty far inboard on this bike. (The whole point - Q-factor.)

That piece of flat bar just got taped in with the Extreme. Shifts really well. The chain does hang up on the flat bar when I shift to the middle from the outer until I bring the FD back out. With it hung up, there is no push to get it onto the inner ring. Probably if I file off the "shoulder" on the top, forward-most part of the flat bar where the chain hangs up, it will behave and fall off. (It does seem to run just fine while "hung up", just quite noisy.)

Another adventure into the unknown corners of "out of spec".

Ben

BCDrums

Ben, I am using a Shimano FD-CX70 derailer to shift a 24-37-42 triple on my 1990 Peter Mooney road bike.



It's available with a 34.9 clamp bottom pull (and five other flavors), and shifts snappily. I am not sure how to define inboard travel in a meaningful way. On my setup, the inner cage plate is about 17mm from the seat post in the granny gear, and there is a little travel still left on the limit screw. Let me know if there is a measurement you'd like.

To add to your out-of-spec adventure, this FD is sold as a double!

ThermionicScott 

Since the CX70 is intended for 46/36 cranks (I think), I'm curious how well the cage shape would handle a 52T big ring. A little bit of grinding might be in order.