[Avy Rider]

I took my bike for a little ride around a rocky area in my town that is being excavated and has some cool rock formations and I banged my drive side crank arm. It's bent inwards towards the frame and comes in contact with my pulley wheel mount. It wasn't even a very hard or fast impact but was enough to bend the arm.

I tried different ways of bending it back at home in my bench vice...broke the bench! lol For now I managed to put a spacer in there to keep it from hitting the pulley mount but I'd like to straighten it at some point.

I'm afraid of bending the spindle instead of the crank arm when clamping it. Does anyone have any experience that they can share?
Thanks!

 

[ChrisKring]

did you bend the spider or the arm itself?

If it's the arm, you would probably need a press to straighten it if it is as bent as you describe. I would probably straighten it with the crash replacement option.

 

[Avy Rider]

It's the arm itself. I bought them last week new and never installed from a seller on Pinkbike. I don't have the receipt though so I don't know if I will be able to get a crash replacement?

 

[Udi]

Solution: buy saint.

 

[Avy Rider]

I still have my FSA chromoly cranks if I want pure strength. I wanted the lighter weight.
It was a fluke that they got bent.

 

[DirtyMike]

Well, My suggestion to straightening a crank arm......remove it, replace with new.

Unfortunatly, I think you pretty much screwed for the Crash replacement without a receipt showing original owner. Never know though, give them a call see what happens.

 

[SteezyWeezy]

sounds like you're SOL

 

[Jeremy R]

It was a fluke that they got bent.

"It wasn't even a very hard or fast impact but was enough to bend the arm."

That is not a fluke.
That is weaksauce cranks.

Saints if you need the 150mm
SLX if you don't.

 

[Bicyclist]

Gravity Lights are notoriously weak.

Shimano FTW.

 

[Udi]

It was a fluke that they got bent.

You keep telling yourself that.

 

[Zark]

Saint cranks baby, do it!

 

[TWeerts]

you could put a metal rod(pipe maybe?) trough the spindle, and another one big enough to go around the crank, then you should have enough leverage.

 

[spocomptonrider]

 

[Avy Rider]

I'll see if the seller still has the receipt and have him mail it to me.
Thanks for the laughs guys.

Funny thing is I bought Saints off a guy just before I got the Gravity Lites. He had advertised them as being 165mm arms but they were 175mm so I had to return them.

 

[rayhaan]

ha ha ha @ the sledge!

and FWIW buy saint...

 

[marshalolson]

i bet if you throw them in the garbage hard enough they might straighten out. if not, they have found a new home. win-win.

 

[DirtyMike]

Gravity Lights are notoriously weak.

Shimano FTW.

I have to agree with this first statement fully, but the second part...Well lets just say while Saints are really nice, there are other brands out there that are good too, that are also strong, and likely better budget than the saints. I mean you cant go wrong for weight or strength with teh saints, but there are other great options out there.

 

[slowitdown]

you could put a metal rod(pipe maybe?) trough the spindle, and another one big enough to go around the crank, then you should have enough leverage.

leverage to do what, exactly? you're assuming this thing can be bent back to its original forging position?

nice dream

 

[Avy Rider]

While I appreciate the suggested alternative brands, the topic is how to go about straightening the ones I have. I realize that they aren't as strong as Saints but the accident occurred while riding extreme terrain that I don't really ever ride. I was there only due to my local trails still having some snow and tons of mud.

As "weak" as the Gravity Lites are supposed to be I haven't yet been able to budge them with all my strength with them clamped in my vice. I actually ripped a section of my bench off! I'm strong as hell for my size but the crank arms just won't bend.

I guess the obvious solution is more leverage so I'll have to look for a pipe to fit over the crank arm.

On a totally unrelated note, is that Lahar guy more than a little nuts or what? lol

 

[MinorThreat]

Now, back to straightening the crank you have . . .

You need a stronger bench and/or vice and interface. Big 12" or 14" Crescent and a 2' piece of 1¾ or 2" Shelby tubing (although mild steel will do in a pinch) ought to give you a rudimentary arsenal for attacking it properly.

Either clamp it in the vice by the faces at the spindle end or, alternatively, you could put a piece of snug-fitting tool steel bar in the spindle hole and clamp the bar in the vice.

My setup:

 

[boogenman]

ahh the trusty mexican wrench

 

[Avy Rider]

I ended up mounting my vice to a thicker bench yesterday evening to try it again but I pulled so hard I messed up my lower back! I'm all doped up on Tylenol 3's with codeine right now! lol

I'm tempted to try hitting the crank arm with a heavy object while it's mounted on the bike but I'm afraid I'll do worse damage elsewhere. When all else fails, use a bigger hammer!!

 

[jsg04]

I bent my non drive side crank arm last year really bad to the point I could not even ride it. I just took it off the bike put it in a vise and hit a few good time with a 5 pound hammer that was rubber coated. It bent back pretty easy and it came out really good but that was the non drive side... I don't know about the drive side.

 

[MinorThreat]

More leverage is usually more effective and "fine-tunable" than a bigger hammer. When in doubt, get a longer cheater pipe - - brains over brawn .

 

[rayhaan]

I personally don't think it is worth trying to straighten the crank arm, it will never be the same again, if you succeed in straightening them, they will always be that slight deflection in the arm, therefore making it pretty tough to pedal properly.
The crank arm is bent now and by trying to straighten it you are going to work harden the material, weakening it further and judging by how weak these cranks are I don't think it would be too safe. They are forged 6061 T6 Aluminium which is not a terribly strong aluminium alloy. As mentioned previously they have been forged, so good luck trying to straighten them, I wouldn't be surprised if the crank arm snaps. Can we see a picture of how bad it is bent please?

correct me if I am wrong, but I just don't think it is worth the bother.

 

[MinorThreat]

^^ On the other hand, there's the school of thought that says if it's toast anyway, there's nothing to lose trying.

My son, who was notoriously hard on cranks bent a Specialized Strongram (haha) drive-side arm and I said "What the hey?" and straightened it in the vice. Oh yeah, I could hear the >ping< >ping< >ping< as I tweaked it back ito place; but since it was going back on an XC bike, I figured it wouldn't get stressed too badly anyway.

Since then, I've pretty much forgotten about it and abused it mercilessly since I did it about four years ago.

 

[rayhaan]

thats true as well..awesome that it worked!

 

[ChrisKring]

This is what you need:

Or you can do the pipe method mentioned. However, what are you going to hold the bottom bracket end with? Normally, crank spiders are not square enough to get ahold of them in a vice.

Again, I would just replace them if they are that bad. Minor tweak, yes you can straighten them. but you said it was hitting the frame and that means it is probably a big bend.

Whatever you do, don't hit them with a hammer while they are in the frame. That might make the replacement cost on the cranks look cheap.

 

[Avy Rider]

It's a slight bend guys. It contacts the upper pulley wheel bracket not the frame itself. With a spacer I was able to make the bike ridable but would like to put the crank arm in its original state.

I might look up a local shop that has the right tool for the job instead of risking it.
Thanks for the input everyone.

 

[Cabdoctor]

I still have my FSA chromoly cranks if I want pure strength. I wanted the lighter weight.
It was a fluke that they got bent.

How much do those things weight anyways?

 

[Avy Rider]

As I recall, the Chromoly cranks, bb and bashring with a single 32 tooth chainring was 6.22 lbs!!!