BlackPowder

Hey everyone,

again not sure if I should post this here or in SSFG (feel free to move @ mods), but anyways;

I was gonna get the Sugino Grand Mighty Crankset plus Hatta BB. But after reading some more about track cranksets, I might abandon this idea and get SRAM omniums instead. In general, the experiences seem to be that Sram Omnium cranks are the stiffer (stiffest?) cranks due to their design with the external bb. Only issue here seems that the stock bb (Sram Truvativ GXP BB) uses bad quality bearings, but this could be overcome by replacing it with an aftermarket quality bb.

So by choosing the Omniums over Sugino Grand Mighty, one would get the stiffer / stiffest Crankset and save money at the same time, even if you replaced the stock bb with a quality one, like Chris King. Is this correct? Or did I miss something?

Thanks,

BlackPowder

carleton

Are you racing with these?

Are you strong enough to flex crank sets?

Omniums are certainly a great value, but they aren't considered the best track racing crankset. Then when you figure in the cost of upgrading the bottom bracket (around $100) the value isn't that great. It becomes a good value. They are popular on the street fixed gear scene because they are the most inexpensive race-spec crankset on the market.

Despite being one of two track cranksets using external BBs (Rotor being the other one) very few use SRAM Omniums. Dura Ace seems to be the most popular standard cranks. SRM (which uses the Shimano Octalink BB) is also very popular for those who are into power data.

carleton

Further...

If you have the budget to afford Sugino Grand Mighty cranks, then you can also get Dura Ace cranks.

If you aren't racing get the ones that look best and match your build because you'll never have to do standing starts, high RPM work, or deal with multiple gear changes during a training session. Changing gears using the stock Omnium bolts is a pain in the butt. Plus knurled chainring bolts don't work on them either. Only superglue.

Flatballer

Changing a chainring on my new Dura Ace crankset was super easy. Just take the front bolts out, the rears stay in place, slap a new ring on and tighten them back down, good to go.

Soil_Sampler

some frames have trouble/will not accept these cranks!

BlackPowder

OK thanks. That means people arent using Omniums because their quality and handling just isnt that great compared to the top notch track cranksets like dura ace, etc.?

But, just concerning stiffness, they are as good as Dura Ace FC-7710, Suginos, if not better? .. with the external bearing bottom bracket .. .. Or did I misread this?

And also, just googled the Rotor 3D track cranks, and, holy smokes they are more expensive than Dura Ace, even more expensive than the Campy Record Track crankset? Whats their deal?

carleton

Will you answer these?:

Explain "handling"?

Why are you preoccupied with stiffness? Again, if you aren't strong enough to flex a lesser crankset, then you won't feel the difference of a strong crankset.

This seems like a "I want the best because it's the best" thread. I'm going to move this to SSFG.

Scrodzilla

carleton

I like bringing threads over hear to you Scrod. It's like bringing one more cat to a cat lady.

Jandro 

QFT. Wish I would have known this prior to my purchase. Do you know of any alternatives, Carleton?

edit: alternative bolt options, that is.

ddeadserious

Scrod sold me some FSA chainring bolts with mine. They have been good.

carleton

Buy:
- 1 set of steel single chainring bolts with knurled backs (the female part)
- 1 set of steel DOUBLE chainring bolts (MTB guys use these)
- strong super glue. I used Gorilla Glue but any would work I guess.

Use the backs from the singles set and the bolts from the doubles set. The bolts will poke through, but they won't harm anything. Test first though to make sure. I used longer bolts than singles to make sure I got enough purchase on the threads as the crank spider is so thick.

If the knurled backs don't set (probably won't) then glue them in.

That's what I did. Worked fine after that.

Adrian_

Good to know knurled bolts don't work on them I was literally just about to buy a set.

Nagrom_

sweet advice carleton.

FixedFiend626

The stock BB is actually quite good on these. I upgraded to one from the first generation model GXP BB (absolutely horrible) and it made a massive difference. Probably not as good as Chris King, but what is..

FixedFiend626

Wow, really? Don't want to get into it with Carleton or anything but these seem to be the current 'go-to' fixed/ss crank, I see them more and more everyday. I'm assuming you run Dura Ace?

carleton

Sorry. To offer some context, this thread started in the track racing forum then I moved it here to SSFG. The guy was asking for "the best track cranks". In the advanced to elite levels of racing, SRAM Omniums are not as popular as Dura Ace.

I ride SRM track cranks.

https://www.srm.de/store_usa/product_...nal-Track.html



If I didn't have SRM, I'd ride Dura Ace for sure.

FixedFiend626

Ahh.. ok. That makes sense, I didn't know there was a racing aspect to the question. So that leaves the question, why do the racers prefer DA over SRAM? Increased bearing drag? I can't imagine the DA's are stiffer, what with the smaller diameter axle.

Nagrom_

It has to do with frame compatibility, and its a bear to change chain rings on the omniums.

They're probably both equally stiff, and both stiffer than you will ever need.

monsterkidz

Between the slightly wider Q-Factor, sluggish stock BB, and the fact that changing rings on the fly was such a PIA, I ditched SRAM cranks and went back to my Suginos.

prooftheory

Carleton also answered this question in post #2. The GXP bottom bracket needs to be upgraded which makes it uneconomical. A pinging, grinding bottom bracket isn't a big deal at 20mph but at 40mph you are definitely losing efficiency.

carleton

All of the above!

Plus the Dura Ace have a nice feel to them. I even prefer them to my SRM cranks. It's hard to describe, but I can feel the difference. The SRMs are stiffer, but he DA feel better. "Stiff as possible" isn't always preferred.

The French National Team sprinters use Sugino Grand Mighty. Well, used...until LOOK made a 1-piece carbon crank for the new LOOK L96:

McRussellPants

I've burned through a couple bottom brackets on my Omnium and I've had them for about two months.

First set I think I messed up the install, but they did get run in real heavy rain every night for a week or so, started clicking pretty bad. The second set has been good until about two days ago. now if I'm full on full on cranking they'll ping, particularly if I back pedal real hard right before. Honestly both could be my fault from messing up the torque when installing though.

I'll probably spring for a Chris king replacement this time. The Sram GXP isn't supporting itself off the bottom bracket shell as much as it could, at the edge with the SRAM cupsits BB Shell|/BB cup, with the Chris King it looks like it the cups will have more support from more contact with the BB shell. hope that makes sense.




The other gripe I have about the Omnium is that if you screw up getting into the clips sometimes your left side ankle will get grabbed by the hex on the crank. I've got a pretty cool skinned spot on my ankle from that, upshot is I got really good at clipping in/out really fast. haha.

prooftheory

That L96 deserves a fapping gif.

FKMTB07

If you're having longevity issues with your external cup bottom brackets (regardless of the brand), check out your frame. You probably need to have your bottom bracket shell faced. Of the bikes I ride that have external cup bottom brackets there are 2 mountain bikes (both shimano), 1 road bike (Sram), one cyclocross race bike (Sram), one gravel endurance bike (Shimano), one track bike (with Omniums and stock bottom bracket). No longevity or durability issues, but all have had proper frame prep done before being built up.

Sram and Shimano external cup bottom brackets have a fair amount of bearing seal drag when new, but you can't really feel it unless you're spinning the cranks while the bike is on the work stand. The bearing seals break in and the cranks spin very smoothly after that. It's a pretty well-designed and reliable setup, IMO. That being said, I've got a couple of bikes with square taper cranks, one with Octalink, and one with a PF30. No complaints with any of those systems either.