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So, I am enjoying my ride in the Cameron Park in Waco, TX climbing on my 29er SS and WHACK!!!! In horror I look down and that is what I see. I check the bolts before every ride too!!!! These are steel and supposed to last. My CBs are steel too! The funny part is that I am standing there looking at all these mess and this guy on road ss is passing by and offers his help. And, of course, he is an mtbr member. Thanks!!!!!
 

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Cb

poff said:
So, I am enjoying my ride in the Cameron Park in Waco, TX climbing on my 29er SS and WHACK!!!! In horror I look down and that is what I see. I check the bolts before every ride too!!!! These are steel and supposed to last. My CBs are steel too! The funny part is that I am standing there looking at all these mess and this guy on road ss is passing by and offers his help. And, of course, he is an mtbr member. Thanks!!!!!
Hard to taco it without popping a chainring bolt first.
 

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4 v. 5

makes me wonder about the strength of a 4 bolt system versus 5. 4 bolts puts one bolt directly across from another. they don't frequently blow up like this, right? but...starfish have 5 arms for a reason.
 

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Cygnus said:
makes me wonder about the strength of a 4 bolt system versus 5. 4 bolts puts one bolt directly across from another. they don't frequently blow up like this, right? but...starfish have 5 arms for a reason.
Agreed. 4-bolt/arm has never seemed like a good idea to me.
 

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Had a similiar incident

about 3 weeks ago, popped 1 chainbolt going over a log pile (didn't recognize it for what it was at the time) and started to have problems immediately. My chain started to come off in transitions between the going down and starting uphill. Finally, when I saw what was going on, it was too late. I have an egg-shaped Surly 104 x 32T. One other bolt was loose at the time, either it started to loosen up after the first one popped, or it started to loosen due to the issue stated below. The other two bolts were damn tight.

Since Surly's are not in stock, I had to put an aluminum Blackspire on it. I was using SS chainring bolts, but went to full size with a washer. After examination I could see that there was too little engagement between the SS chainring bolts and the crank on the body of the bolts. So it goes.

BTW, having a failure that way is a feature of the Surly. It is now coffee-table art.

Rick
 

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shiggy said:
Agreed. 4-bolt/arm has never seemed like a good idea to me.
Gulp! And here I am building up a brand new ss with a 4-bolt XT crank.

I've had no issues at all with my current XT setup and I am often not gentle on the pedals. I'd never heard of this issue before. But those pics and stories are scary and are making me think....

Would a chainring protector ( I've always had one ) help to prevent this? Maybe not if the bolt actually shears, especially on the inside.

Ed E
 

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so did the people at surly already deny your request for a free chainring
or are they now going to deny it since you had to go trashing them on the big bad internet
btw it's good that you showed us three pictures just in case we couldn't tell what happened from the first one
 

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iliketoridebikes said:
so did the people at surly already deny your request for a free chainring
or are they now going to deny it since you had to go trashing them on the big bad internet
btw it's good that you showed us three pictures just in case we couldn't tell what happened from the first one
Yeah, the title might be harsh on Surly but I don't think anyone who read through this thread took away bad feelings about Surly rings. Sheared bolts, 4-arm cranks (maybe?) and over-zealous tightening of said bolts are possible culprits.

I am getting the Surly 4-bolt, 34 tooth ring just like the one pictured above and have no doubts or concerns about doing so. Surly rings are good stuff.

Ed E
 

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edemtbs said:
Sheared bolts, 4-arm cranks and over-zealous tightening of said bolts are the culprits.
FWIW...

I have had this same thing happen twice on 5-arm cranks... and I haven't had any issues with my 4-arm cranks... I guess I learned my lesson. ;)

One of those failures had the steel chainring go most of the way through my steel chainstay. :(

bb
 
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