Mountain Bike Reviews Forum banner
1 - 20 of 81 Posts

·
Registered
Joined
·
37 Posts
Discussion Starter · #1 ·
I had an interesting experience today. While riding my Superfly on my first real technical ride I went down a long technical jarring descent and started pumping up a hill when all of sudden I lose all pressure on my left foot. I crash and in amazement look down to see the crank arm attached to my left shoe instead of the crank. Yes, the crank arm fell off. It wasn't properly tigthened. I took it to a Trek dealer in the town I was visiting. The crank was hogged out so I need to get a new one. I am starting the process to find out who is going to have to correct this. I also had a bolt come out of the crankring and the others were all loose. From this forum, the crankring bolts being loose seems to be a common problem so I would warn everyone to check the crankarm also. You may avoid the long, long walk into town I experienced today and also the headache of trying to get it fixed. I will update everyone when I find out who is going to have to pay for the new crank.
 

·
Registered
Joined
·
1,155 Posts
Glad your not hurt.

There are a couple issues:

1) Has nothing to do with the superfly, it is a crank issues.

2) If they replace the cranks, you are very very lucky. It falls on your shoulders to keep the crank bolts tight. It takes literally 15 seconds an allen wrench.

3) I am surprised you did not notice the crank loose before this happened. I would think that sucker would have been wobblin' all over the place and very noticable.

Again, glad you were not hurt, but you need to take care of you bike, it has nothing to do with the bike shop-
 

·
Harmonius Wrench
Joined
·
8,254 Posts
Sorry to hear that!

I work in a shop and generally this sort of thing is on the shop that built it. Assuming that you bought it new, this should be a no-brainer. The assembler/shop is responsible. If they can prove by way of a checklist, or whatever procedure, that it was assembled in a professional manner, then it's on the manufacturer.

Good luck.
 

·
Registered
Joined
·
204 Posts
i hear a lot of this how the chainrings bolts come loose on the superfly and people come on here posting, sound to me the shops are not checking these things before they let the bike go.. its def not the cranks they are a pretty soild crankset...
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #6 ·
My fault after three months?

I try to be reasonable, and I will take the blame if it is my fault. That being said, I think it is reasonable to expect if you buy a 3k bike that it should be the shop/manufacturer to give you a bike in which the crank arm would not fall off in three months. I am guessing that the bike came with the crank assembled and the shop just assumed everything was tightened as it should be.

As to the part that I should have noticed, I am also surprised that I didn't but crank arms fit pretty damm tight even when not torqued on. I also think it was related to the fact that I just had gone down a long jarring downhill so there was more lateral movement than the bike had ever experienced so it might have been loose the whole time and I just never noticed. The superfly was creaking a little, but I think if you look at the threads here that it is normal for the superfly.
 

·
Registered
Joined
·
3,493 Posts
Creeking is not normal.
It means something is lose, broken or about to break.
It is your responsibility to do maintenance....which includes check bolts to see if they are loose.
You have been riding a bike for 3 months off road....things will and do come loose.
 

·
Registered
Joined
·
1,047 Posts
Did your shop tell you to bring it in after a few rides or a month after a break in period? If not, find a different shop. If they did tell you, and you didn't take it in, it's all your fault.

Cranks loosen up after the first couple rides whether they are new, or being reinstalled, and have to be checked.

A long downhill wouldn't do it. It take several rides for them to loosen up.
 

·
Registered
Joined
·
1,155 Posts
max_cat said:
I try to be reasonable, and I will take the blame if it is my fault. That being said, I think it is reasonable to expect if you buy a 3k bike that it should be the shop/manufacturer to give you a bike in which the crank arm would not fall off in three months. I am guessing that the bike came with the crank assembled and the shop just assumed everything was tightened as it should be.

As to the part that I should have noticed, I am also surprised that I didn't but crank arms fit pretty damm tight even when not torqued on. I also think it was related to the fact that I just had gone down a long jarring downhill so there was more lateral movement than the bike had ever experienced so it might have been loose the whole time and I just never noticed. The superfly was creaking a little, but I think if you look at the threads here that it is normal for the superfly.
By all means give it a shot, it would be awesome if they replaced it. Hell, I guess I would TRY also, even though I would expect a "take a F'ing hike".

BUT, tightening crank bolts should be done at least once every couple of rides, especially when you first get the bike as they tend to 'settle' a bit.
 

·
Some Assembly Required
Joined
·
4,063 Posts
If this happened on the 1st - 2nd or 3rd ride, it's on the shop. But you've been riding it with them loose for 3 months, it's on you now. You should czech all major components for at least the 1st month of a new bike. Parts work loose until they have "seated properly". After a while of czeching the parts you'll know what is staying tight and what is prone to loosening up.
Even if the shop tightened everything to torque spec it is still possible for stuff to work loose. Get to know your bike inside and out.
 

·
Harmonius Wrench
Joined
·
8,254 Posts
ArizRider said:
Lifetime maintenance policy, nice, where do I sign up....
Actually, many bike shops do have lifetime service policies. ;)

I have seen customers come into our shop within the first year with Truvativ/Bontrager crank falling off issues and they are replaced without question. At least a dozen cases in our shop alone involving all three brands that we sell.

Your mileage may vary...........
 

·
Registered
Joined
·
1,610 Posts
man w/ one hand said:
If this happened on the 1st - 2nd or 3rd ride, it's on the shop. But you've been riding it with them loose for 3 months, it's on you now.
Is that what the owner's manuals and the shop said?

I've never been sold a bike and asked about my ownership of a torque wrench, or my knowledge in the use of such tool (which with carbon cranks, would be in order).

Nor has any shop ever informed me that it is my responsibility to take care of such matters after 3 rides.

Does your experience differ?

Imagine that we are talking about a $300 dollar commuter bike instead of a $3000 mtb. Does that change the equation?
 

·
Registered
Joined
·
3,060 Posts
max_cat said:
I try to be reasonable, and I will take the blame if it is my fault. That being said, I think it is reasonable to expect if you buy a 3k bike that it should be the shop/manufacturer to give you a bike in which the crank arm would not fall off in three months. I am guessing that the bike came with the crank assembled and the shop just assumed everything was tightened as it should be.
A properly torqued crankarm should not loosen itself over 3 months, unless you bought a set of crankarms with known issues. I weigh 250#, and have never had a crankarm come loose on me--on a bike that I built anyway. Properly torqued bolts do not generally "work loose" in the manner you have described (though problem bolts or incorrectly torqued bolts can). Those threads should have been loctited anyway.

Check with the shop and find out what their warranty is. Failure within 3 months is unacceptable.
 

·
Thread Killer
Joined
·
771 Posts
whoa! i have bonty cranks on my gf advance...how can i prevent this from happening? just tightening everything before a ride?
 

·
Registered
Joined
·
206 Posts
is this because all this crap is made in china?

i have been shocked to read about serious breakage problems on new bikes that could seriously injure the rider. if the steering wheel fell off while driving your car, would you idiots claim that you should have checked the bolts before each ride?
if this happened on older bikes before the chinese invasion, i was not aware of it.
 

·
Registered
Joined
·
266 Posts
i work at a shop that has lifetime tuneups with the purchase of a new bike, and i, myself, have ripped crankarms off. i have recieved free cranks and have gotten free cranks from bike companies for customers. it is worth a try. any good shop will do whatever they can for a customer if they are a decent shop.
 
1 - 20 of 81 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top