I have a Ultegra Crank 9sp double / standard crank, and the rings are staring to look like shark fins. I just raplaced the chain / cassettte last fall. I have put about 5k miles on the bike. I bought it used. So, I don't know how many miles are on the original.

But, when I look at the prices of the 105 10 speed cranks, they are approaching the cost of the chainrings. Would this cause a problem replacing a 9sp crank with a 10sp crank. Also, finding new 9sp cranks are becoming more and more scarce, at a decent price cept for fleabay.

So, would it better to get new chainrings, I haven't experienced much skipping if any, but I am worried that the shark fins might wear out my chain faster than needed. Any help would be appreciated.

The teeth of a chainring, being aluminum, aren't going to damage your chain at all. As long as the bike is shifting ok and not skiping, I'd just continue to use your current crank. Often, a set of chainrings cost as much or more than an entire replacement crank.

That's what I was thinking when I looked at the price. So, I figured I would just buy a new crank, but if you think they are OK until they start skipping on the chainring, then I won't replace. Maybe, I'll just wait until I see a good deal on a crank and then grab it. I did see a 105 9 speed double for $32. new on fleaybay, but there's always the risk there. I just need to make sure it would fit the bike.

Just make sure the BB is compatible (octalink vs hollowtech etc), should be good to go, I would go new crank myself.

OK. I didn't think to check that. If the new crank will fit, I think I might as well upgrade.

What's the world coming to? Dude....Keep the cranks, they're not throw-aways. LOL You don't have to buy or use Shimano rings, they just brainwash you into thinking you won't be able to shift anymore or something. There's lots of 130 bcd rings out there. For instance, a set of 39/53 Vuelta rings run about $45.

If you trash your crank and get a new one, what do you do with the old one? Ebay it? You may get a few bucks for it after all the fees, the time and labor to list it, box it and take to a shipper.

But that's just me.

Keep, the old ones for a build up down the road, maybe you find some chainrings on CL some day. I'm getting my ultegra triple and external bottom bracket later this month. My old biopace triple works fine, I just want to do the upgrade! All comes down to preference.

New chainrings aren't that expansive if you shop around. The Ultegra crank you have is a nice unit, so no need to throw out the baby with the bathwater. And the difference between the 9-speed and 10-speed stuff is mostly in the bottom-bracket tech used (octalink+cartridge for the 9-speed, external cups+cartridges for the 10-speed); the ring spacing is identical, as are the chainrings.

Great chainrings from FSA, SRAM/Truvativ, Stronglight, Vuelta or Shimano won't break the bank: you can often find them online for $25-40 a piece, which is a lot cheaper than a new equivalent to your Ultegra crankset. Shop around, do the math, and go for it!

And yes, chainrings can and do wear out: the tooth profiles often won't mesh with a new chain if the rings are too far gone (i.e. were trashed by a worn-out chain).

True but the OP said his bike is still shifting well and the chain isn't skiping. He was concerned the worn rings would damage the new chain and that won't happen. If it ain't broke, don't replace it.

If you eventually decide to replace everything, know that you have the option of going to a compact crankset if you want to stay a double. This would allow a lower possible small chainring.

I was looking at compacts, but for some reason the price is much more than the triple Ultegra's. I don't know why, newer maybe? But at 33g difference, I guess I should stay with the triple. I never use the granny ring on mine anyway, but the price savings of 70 dollars seems well worth it.

I didn't realize that I could change to the compact without changing derailurers / shifters / cassetts, etc.

What would I need to look for if I did this. This would help on some of the hills that I have to climb.

All you need is a new crank, and the proper BB to go with it. "Compact" cranks are nothing more than a 110 bolt circle diameter (BCD) crankset. It's been around a long time, so it's not special to any one or two brands..... it's universal.(Except some Campy stuff, they are always doing something to the rings to make them proprietary!) You can use any brand with you shifters, cassettes ect. Brand makers want you to believe you need to stay with the same brand for everything, but they just want to sell you their stuff.

A 110 BCD can take rings from 34 teeth all the way up to 58 teeth. Compact cranks are often sold in a 50/34. You are certainly not limited by those rings though. Replacement rings can be from any brand are can be had inexpensively. With 11 tooth cassettes these days you can even get by with a 46 or 48 depending on your needs.

Here's a real nice 48/34 Sugino crank for instance.... https://www.velo-orange.com/suxddocr48.html from this selection of cranks....https://www.velo-orange.com/cranksets.html They take square taper BB's. Easy to find, inexpensive. For those that may not know....Sugino has been making cranks since the 70's. A very very good brand.

Many choices beyond Shimano and the other big brands!!

Chainrings are cheap, 9/10 are the same, fully compatible. Loads of NIB stuff on eBay. Cranks are not 9 or 10 speed, despite marketing. Really need to talk hollowtech vs. octalink (inborad vs. outboard bottom bracket). Most of my bikes are still so-called 9 speed cranks, no worries. Rings, chains, cassettes and bottom brackets are replaceable parts that will wear out. Hard to imagine needing a new crank without a wreck.

About 4 or 5 years ago, I also noticed the teeth on my 9 speed ultegra chainrings were looking like shark fins. I bought new chainrings at the time and out of curiosity, I compared the brand new ones to the used ones. I held both rings next to each other under a large magnifying glass and the tooth profile looked identical so I cleaned the used ones up and put them back on. The new rings are still sitting in my toolbox awaiting the time when the used rings someday give me problems. I have at least 3 times more mileage on this bike than yours so I'd say you're worrying about nothing.

Ok. I will forgoe getting new chainrings. Thanks for all the help, saving me $$$.

Get a new crank. WHYYY U ask?

I bought a used full ultegra set-up.
Put 10K on the bike in 2 1/2 years and my chain ring looked fine, but they were replaced by the previous owner. I could tell as they were black vs the silver standard shimano of the time. In anycase, one day I was starting from a stand still and my Crank just cracked in half and down I went.
I was okay, but the crank was like someone sawed it off half way up. No warning, nothing.

Why do I say this?
I assumed the bike had limited mileage, maybe yes, maybe no. The crank could/should last 40K to failure (shimano says so). they also said my problem was a common issue as the crank is hollow to save weight.
I bought a crank for $69.00 online.
these guys have them for $110 https://www.bicyclebuys.com/drivetra...ks/1577120PART.

if you need a 170 try nashbar $79.00
https://www.nashbar.com/bikes/Product...a-000423bb4e95

Just my two cents

OK, if it just get a new crank, then would going from a 172.5 to a 170 length cause a problem?

I'd say yes. It might not seem like much, but I can tell the difference between 170s and 172.5 cranks.