Ask Prolly: Is a 9t Fixed Driver Really the Answer? Oct 18, 2010


I’ve gotten this question a few times since posting the Wheel Talk x Specialized P-Fixed. People are apprehensive about such a small tooth-driver on a fixed, asking if this is too much too soon? And now, with other companies talking about making 9t fixed drivers, I began to wonder: could a 9t fixed driver support the constant wear and tear of riding fixed?

The other day at Affinity, Ben and I were talking about it. Right off the bat, he showed me two torn drivers from a few months of riding on his BMX this summer. Ben’s a smooth rider and he’s also anal as hell about his bike (like most mechanics). He raised a good point: I wonder how long these 9t fixed drivers will hold up? Is a 9t Fixed Driver Really the Answer?

Check out some more photos below and feel free to comment!


Would you want this happening to your fixed driver after landing a big gap?


Or riding through traffic?

Seems pretty risky. What do you guys think?

  • jus sayin’

    why not just ride a bmx?

  • Thrasher

    A 9t application on a fixed gear is ridiculous.
    Shadow chains wear and tear sprockets and drivers like nothing, and also a chain’s lifespan is severely shortened. People seem to think running the same chain for over a year is smart.
    Replace your chain every few months, ride 42-16t(FGFS).

  • tjs

    As far as I know, this will happen on any cog/driver that is smaller in diameter than a 13t cog. There are serious chain engagement/disengagement issues with cogs of that diameter if the teeth are not profiled. Take a look at any new cassette and notice the profiled teeth on the small cogs. A 9t on a fixed gear? No thanks.

  • 36:14 has given me 0 issues but my chain will slap if my tension is down. I think it’s mostly the increase in fatigue when you run a compact gear.

  • ignoramus

    cause bmx ain’t fixed gear

  • misha

    36:14 served me well, also 36:16 that im surrently riding is great and i cant see it tearing apart. Sure 9t might look good, but there is no way its going to hold up.

  • joe

    what company made the above driver if you don’t mind me asking? i ride bmx nearly every single day of my life 23-8 (tree to primo mix) and i’ve had my current 8 wrapped with a shadow chain for a while and i haven’t seen that sort of damage, ever. the only time i saw a friend mangle a 9 like that was on the freecoaster hubs khe put out. (thanks)

  • dinosaurman

    trick track aint fixed gear its bmx.

  • I’ve seen this with BMX drivers numerous times. Though my 9T driver’s teeth are still fine, I’ve snapped a 710SL chain twice. Yes, the smaller the gearing, the bigger the stresses on each part in the system. Prolly, you mention chain slap, which would also be more pronounced than on a 20″ bike’s chainstay. I don’t think 9T for fixed is a good idea for those reasons, but I’m willing to let someone else do the real-world testing.

  • Tyler Johnson

    I am running a 36×13 and it is the perfect gear ratio for me. I dont plan on switching, BUT I also do not do grinds. I think people that do grinds will probably want to do smaller… Either way their stuff will wear out quick, and as long as people realize that beforehand then I don’t think it matters.

  • tim

    that driver looks like a freecoaster driver.

  • Chris

    Sure they arnt going to last if they are built like normal 9 tooth drivers. However if maybe made of carbide or made like bandsaw blades used to cut metal. Its Bi-metal meaning the teeth of the bandsaw are a different metal than the rest of it. And if say something like submerged welding is used. Then the welds would end up being stronger than the actual teeth. So they are moving in the right direction purpose driven wise, but structionally i think they are a little off course.

  • Vas

    yea, what brand is this? i got 9t and never ever seen that sort of damage….

  • I just began riding 36:14 this week, and I can’t say I’d want to change it. The 14t cog is a good middle ground. And this is after riding 46:17 for about 2 years. I actually like the way the 36:14 looks opposed to the smaller sizes that are popular amongst the BMX community.

  • Coop

    I’ve just started fixed gear, I get really stoked on the old style tricks. (Keos, wheelies, simple flatlands stuff) I don’t like the way most airs and vertically-inclined tricks look on a fixed gear and I find putting pegs on a track bike silly.

    In short, I’m getting a BMX bike to do BMX tricks, and keeping my fixed gear for fixed tricks. I don’t like how the sport is heading towards BMX so quickly, just seems obtuse to me.

  • My first setup on a FGFS bike was a 12t and it was always making popping noises all the time even when I was just cruising. My brand new Shadow chain suddenly snapped on the way up a hill. I will never go below a 13t.

  • aj a ustin

    shit seems pointless

  • chris b.

    Seems like it’s a lot of constant torque distributed over very few points of leverage, but that’s just my own ignorance speaking.

  • I’m running 23:9 and I haven’t noticed any bit of wear on my rear driver. I imagine it would take quite a bit of bashing and quite a bit of time for it to ever get to that point.

    I used to burn out 42t chainrings before I ever began to do damage to my 16t cog. So I’m not entirely convinced that it’s the amount of teeth, as it is the metal it’s made from.

  • I think the bigger issue other than the cog wearing way quick is the custom lock ring that would need to be made in order to free the chain from hitting the lock ring. If you run a 12t currently it needs a custom lock ring so the chain does not interfere with the lock ring. On that note how minimal can you make a lock ring before its to small and dangerous?

  • shaeshdfeeshd

    im studying metallurgical engineering at the university of utah, my TA and i had a discussion about this, it definitely comes down to machining and metallurgy to make this setup work. if you use low carbon steel like some chinese companies are going to use then your parts are NOT going to be round or strong, that is a simple fact that you all can relate to. now when you get deeper into it, the process that SPECIALIZED is using to machine their bits is much MUCH much more advanced than ANY freecoaster design out there. trust me, when you have moving parts like on a driver or freecoaster hub then you have wear issues, when specialized releases a HUB COG CHAIN SPROCKET combination that is DESIGNED to work in a much simpler way than a freecoaster by being bolted all together it will end up being WAAAYYY stronger than even the most perfectly heat treated 13t MKE cog and lockring combo.

    by the way i rode a 28t tree spline to 12t MKE and didnt clean it once all winter, sh*t was fine because of the metal they used.

    just because someone is REALLY good at breaking sh*t doesn’t mean they are doing it right, dont you agree prolly? (i too rode a steamroller to DJ fork)

  • to me this seems like a bit of a fruitless argument. this is all part of progression, it may stick, or it may be obsolete among the majority of riders soon after it comes out. i will say this though, if it is made of quality steel/metal it’ll last.

    it seems like as of late, people have been arguing more then riding. its never going to be a homogeneous scene. some dudes are still riding deep vs on cutters with taper cranks, and they still kill it. it’s not about the bike its the way you ride it hahaha.

    there is my 2 cents

  • Rui

    Is it just me or aren’t the small rings/cogs used on BMX bikes there for the specific reason of increaing grown clearance (since the 20 inch wheels put the bb pretty close to the ground. With 700 c ( and the already higher BB heights of FF bikes), are these any other advantages to using compact gearing on FGFS bikes?
    If there arent any other advantages that ground clearance, what is the point?

  • the smaller the sprocket, the larger the tires. That is if your frame is spec’d for a specific size sprocket.

  • Bingo. Working around a smaller chainring allows frame builders to to give the bike better tire clearance, while making the chain stays shorter to give the bike a tighter geo. Slamming the rear wheel closer to the BB makes it easier to pop up the front end, and manipulate.

  • that is a driver from a khe made freecoaster… they are notorious for blowing up. you cant take the jankiest 9 tooth driver and use it as an example. and to anyone saying that a shadow conspiracy chain causes wear check and see if you put it on correctly. they are directional and on a “quality” sprocket that is 1/8″ to accommodate a 1/8″ shadow chain they are amazing especially when on a 7005 aluminum gear. anything can be argued one way or another. the 9 tooth drivers have proved themselves in bmx, which in my opinion is a sport that puts more abuse on a bike than fixed freestyle aside from drive train. i can deff. agree that any variation of track or fixed gear bike is under a lot more drive train stress than a bmx bike.

    so in conclusion, i say that i do not think a nine tooth cog on a fixed freestyle bike would be a problem. but at the same time say why really push it? a lot of frame/wheel combos will give you chain slap issues. if it is not for you dont get it. it is obviously something people want to ride so dont fight it or hate on it. just let it happen and it will prove itself to be a staple or just another trend…..

  • I ain’t hating I just wanted to see what people thought!

  • Tyler Johnson

    Slum- {Working around a smaller chainring allows frame builders to to give the bike better tire clearance, while making the chain stays shorter to give the bike a tighter geo. Slamming the rear wheel closer to the BB makes it easier to pop up the front end, and manipulate.”

    I did all that with the shadow and you can still run almost any size sprocket! JUST SAYIN! hahaha

    cant wait to see people out using the specialized stuff. Looked real good in vegas, congrats..

  • I used to run 1/8 34-12 but it felt a little rough. After a broken chain i swapped to 1/8 38-14 which felt pretty good, and now i run 3/32 36-13 and things are smooooooth. I think i found the sweet spot. I was a bit weary to run 3/32 chain but it seems to be holding up well so far.

  • BMX has gone as low as 8 but you may have noticed that 25/9 was the size everyone was running three years ago and most are running 28/10 or 30/10 now. Sure, the mainstream companies were slow to follow and have spec’d bikes with 25/9 in the past couple years, but you don’t look to what those companies are doing to get an idea for the “direction” of the sport, do you?

  • Kenny

    ive been rocking a 60/12 for almost six months. i say gimme that 9t.

  • A Shafer

    I’m running a 28t animal sproket and an 10t odyssey quartet driver and just put on a new shadow supreme chain. Now the chain seems to hang on the top of each tooth of the rear driver only when under stress from peddling. I have the chain on in the fish swimming up river direction and have turned it around in every direction and the problem persists. I was going to buy a new front 27t sproket and new 9t driver. Will this fix my problems or is it the chain? help!