sagbuya

has anyone, especially someone who has a trek t1, had problems installing sram omnium cranks? my lbs tried putting them in but the chain ring guides wouldn't clear. spacers might work but the chainline would be way off. can someone please help

TejanoTrackie 

Chainring guide? Do you mean the crankarm spider is hitting the chainstay?

spaceballs

I think this is pretty common with these cranks. I have seen a few frames that they wouldn't fit on, and I sold a set of s300s to a guy who also said the Omniums wouldn't clear the chainstay on his steamroller. The spider is really fat and just barely clears the chainstay on my Bareknuckle. I have maybe 2-3mm of clearance.

Now, while they aren't Omniums, the less expensive SRAM s300 crankset is a similar design, but with less material. It might work, but isn't exactly the same thing. But the thinner spider and 130mm BCD might give you a bit more room. Same bottom bracket and general crank design, etc.

I am sure I am not the only one who has seen these cranks not work on a particular frame. Perhaps we could compile a list of frames these cranks will and will not work on. Then again, someone else might chime in and say they did work on their steamroller, etc.

cleanupinaisle3

Thanks for letting me know. I was thinking of Omniums for my next crankset!

Dr. Banzai

No need for Omnium's massive 144bcd. I have the Bontrager Race Omnium wannabe cranks on my stock bike and they work perfectly fine. 130bcd. For the perfect chainline on a Trek T1 you need the chainring set behind the spider.

I've ridden incredibly strong 4130 cranks for most my life and find the stock cranks on my T1 absolutely fine.

carleton

Seriously. Maybe one well-placed dent of the chainstay will do the trick.

Or



Filing the backs of the crank spider.

I've heard of both solutions being used. I actually bought a set of Dura Ace track cranks from a Masters World Champion who shaved off a few millimeters of the tip of the crank arm to clear his chainstay.

spaceballs

A lot of frames I have seen even have a crimp on the chainstay to make room for chainrings.

I don't really know that much about frames, but would an "after market" dent in the chainstay weaken the frame that much?

TejanoTrackie 

I don't think it's a good idea to deform aluminum by impact, because it's pretty brittle, and could crack. Steel is far more ductile and forgiving. And carbon fiber is impossible to deform without damage. Filing the crank arm spider seems to be a far safer route.

spaceballs

Just to give you a little idea of what the inside of the SRAM Omnium spider looks like. The crank on the left is the SRAM Omnium and the crankset on the right is the SRAM s300 road double with a singlespeed chainring on the inside.

This is somewhat of an apples to oranges comparison, as I have no idea what the SRAM s300 track crankset looks like. But it should give you a little bit of an idea as to why the Omniums might not work on every frame.

f50fan

woahhhhhhhhhhhh. well thats quite a difference.

carleton

Wow.

I retract my suggestion above. Sorry and good luck.

spaceballs

Like I said, the pictures compare an Omnium track crank to an s300 road crank, so this gives us no idea of what an s300 track crank would look like compared to the Omnium. However, I would expect the s300 to have nowhere near the beef of the Omnium.

adriano 

many in the tour right now are using 110bcd so 144bcd nutswingery is silly.

also, steel cranks could actually have poorer power transfer.

bleedingapple

oh they are soooo sweet... i was worried about them fitting to. they did and i love them, super stiff and pretty

Kylet5285

I have a sram omnium crank on my surly steamroller 2010. It fits just fine, but I was quite concerned when the crankset came in the mail and it looked so bulky on the inside edge of the chainring. lucky me it fit! The exceptions to bike component compatibility are always frustrating. You have a great idea for your bike in mind and then the d*mn thing just won't fit together, and it always seems like you only need .5 to 2 mm more of clearance! haha

sagbuya

i exchanged them for sugino 75s

spinerguy

As I commented in another thread, had placed an order for this crankset. While waiting for arrival and reading many BF threads, some as recent as mid 2012 stated that it was a hit or miss fitting and so far has not been corrected by SRAM. Well that's not entirely true.

I received my 2012 model Monday and was installed right away. I want to positively confirm that spider has been redesigned and appear significantly thinner than the one depicted in spaceballs photo. Although still somewhat beefy it got be at least half the thickness, it should be able to fit many of not most frames out there.

By the way, the 8mm allen wrench that holds the non-drive side arm requires quite a bit of torque, there's no way in hell you can tighten it to spec with a multitool (fyi). Finished the build with a Soma 17t cog and SRAM chain, so far got in 2 test rides: 8 and 54 miles, very stiff, smooth and free of any creaks of binds, grinds and chain line is just perfect. Not bad for a tool-around bike.

Scrodzilla

As I'm sure you've also read in more recent threads here, there are still many people who have clearance issues with 2012 Omniums and there are variances in spider thickness from one set to another - and often variances on the very same crank arm. The subject has been beat to death, actually.

prooftheory

You also didn't say what frame you put it on. That doesn't look like the screwed up version of the FTP or a Trek t1 so its entirely possible that you wouldn't have had issues with a 2011 version anyway.

Scrodzilla

True. There aren't many steel frames (if any at all) that are known to have issues fitting Omniums.

adashiii

For anyone else searching this topic related to an Aventon Mataro frame, the sram omnium with 165 arm hits the chainstay, no clearance.
I'm going to try file the arm, someone in this thread mentioned it, gives me some confidence.

veganbikes

This is a thread from 2010 and you are posting about a bike that is no longer made (the company makes low initial cost bicycle shaped mopeds and maybe some of them are sans-throttle and could be a bike) and a crankset that is no longer made. I would not file a crank arm they designed it in such a way to work as is. Get a crank that works well and isn't so goofy in fit a 24mm spindle can be spaced out as need be.

IAmSam

Since this thread is now declared dead - want to hear something funny? I've seen some Aveton e-bike adverts on TV the past few days

veganbikes

They are crap and the company doesn't know what they are selling. We had a customer who needed some parts for his bike and they couldn't figure what parts were needed and kept repeating exactly what we already knew and could read on the website even though they went to their engineers.