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Old 10-06-04, 12:46 PM   #1
RalphieTB
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Help! What am I doing wrong?

Hello all,
Don't know if this belongs in the mechanics forum, but I seem to be destroying chainrings.

I only seriously got into this a couple of months ago for weight loss and to save gas (commuting and such), and in that time I've catastrophically bent two chainrings. Bent the outer chainring 90' to the rest of itself, that is to say, folded in half.

I've since taken the bike into a LBS for a new crankset, hoping that a newer piece of equipment would be stronger. But after a bit of research, the Shimano chainrings are sade to be made of Aluminum. Are all chainrings Aluminum or an some type of Aluminum alloy? I bought my Raliegh in 97 or 98, can't remember, and I'm told the original crankset was an Impel (though it had no markings on it). It was a one piece riveted unit. Was it steel or aluminum as well?

Anyway, is this normal? Am I peddling too hard? Is it a matter of technique? Am I just too strong? Is it cheap chinese junk parts? What is going on?

No, I am not joking.
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Old 10-06-04, 03:05 PM   #2
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Send us some pics. Are you able to post some pics?
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Old 10-06-04, 03:20 PM   #3
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either you have junk parts on there, or you are slamming the chainring into something to bend it.. I've never seen one bend in half just by pedaling.. even hard pedaling...

post some pics

jeff
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Old 10-06-04, 03:41 PM   #4
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Blackspire make nice rings, and you can get beefier metals though all probably will be Alu alloy. You or somebody smacked the ring. They can snap, get worn, bending is from a hit.
Non-ramped chainrings seem a little stronger, the Blackspire Epic I got was 1-2 mm thicker.
Perhaps you need a bashguard?
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Old 10-06-04, 05:47 PM   #5
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Surly makes a steel chainring but they are primarily meant for single speed.
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Old 10-06-04, 06:01 PM   #6
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Quote:
Originally Posted by RalphieTB
Anyway, is this normal? Am I peddling too hard? Is it a matter of technique? Am I just too strong? Is it cheap chinese junk parts? What is going on?
I can answer all of your questions but the last one. Bending chainrings isn't normal. You are not peddling too hard. It isn't a matter of technique. People who are lots stronger than you don't do it. It's not the aluminum parts. What I don't know is what's going on.

I kind of think that you have some additional information, like when and how it happened that you're not shareing with the rest of us.
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Old 10-07-04, 06:06 AM   #7
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Bent rings are usually caused by improper/poor shifting, when shifting and at the same time applying too much force on the pedals. That is why you should ease up the power when you are shifting. If your planning to go up a steap hill, shift before it is hard to pedal.

Remember to maintain your cadence at about 80~95rpm, this way you wont be able to apply too much force, to be able to bend your rings.

This goes with both the front and the rear. But most of the time it happens to the front becuase of the greater Tooth difference.

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Old 10-07-04, 07:01 AM   #8
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I've never heard of improper shifting or any force this side of brute strength on the bike that can bend a chainring in HALF unless there wasn't something wrong with it in the first place or it hit something.
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Old 10-08-04, 06:56 AM   #9
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I wasn't shifting when it happened. Both times the bike and I where at a stop. First time on level ground crossing an intersection. I started pedaling, bent the chainring and had to coast to the other side of the street. It took a chunk out of my leg when it did too.

Second time I was going up a hill. Stood up to get extra leverage, and bent the chainring. No shifting.

I usually don't shift out of the large chainring these days. There was no trauma to the chainring prior to this. No banging, no accidents.

Now, I am a big guy (hence the reason I'm biking), but I don't see how that would be a factor from a seated position. And while I do not doubt that there are people who have stronger legs than me, I would also say that percentage wise, there aren't many.

I work on getting some pics.
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Old 10-08-04, 10:06 AM   #10
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OK, here are the pics...





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Old 10-08-04, 11:01 AM   #11
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Garbage looking ring, light metal that has been shaped\ curved to add strenght.
Also the teeth show major wear, poss the crank arm was too far out, bad chain-line and unequal stresses.
Basically it looks cheap, lightweight. Being multi piece, it doesn't have normal bolt pattern ( which go through the front\ big chainring- so its not even a repairable item.


Now, what I'd try is (it's a mtb^?=small rings?) just get a bike or your LBS to pull a 5 bolt standard Shimano crankset, for what looks like a tapered spindle. Check the rings for wear, yes they will be Alu alloy, those look loke potmetal. The only curved or shaped ring like those are is the mid ramped ring as it has 'stuff\ramps' on it, needs to be thin.

Having a standared bolt pattern makes replacing a ring very easy.

Sorry to sound neg...you need more HQ equiptment.

http://www.pricepoint.com/detail/133...w_-XTR--BB.htm

Notice the bolt pattern and construction of this drive part.

Last edited by jeff williams; 10-08-04 at 11:53 AM.
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Old 10-08-04, 11:34 AM   #12
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If your a big guy, you need beefier stuff... a few weeks ago on a ride, I passed a large guy, and later on I heard he was riding with other people in my group, went to stand up on the pedals to power up a hill, and snapped his left crank clean off...

And it was Campy stuff.. so it wasn't cheap.. but ya gotta know... if your a big guy, you have limitations

jeff
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Old 10-08-04, 11:40 AM   #13
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One of the problems is that is a really cheap chainring. (Cruel, but true.) It's supposed to bend or break. Next time, buy better. No, a good beefy crank will not be cheap. Sorry, but cycling is not a cheap sport. Good luck.
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Old 10-08-04, 12:50 PM   #14
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Well, as I said, it was what came with the bike. OEM. Says Sugino on the back of the crank.

Thanks for the input. I'm waiting for bike shop to call me when the new crankset comes in. Now, the newer cranksets (I think I have a Deore variant or somesuch on the way), its a standard bolt pattern, right? Much easier to replace or alter gear ratios?
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