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Old 09-29-12, 07:33 PM   #1
mkansari
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Need help! pedal snapped off !

I was riding down the beginning of a trail and kind of started losing control because it was so steep. Out of nowhere this small POLE appears and my pedal smashes into it and snaps off. My pedal is in two pieces and the arm's threading is damaged. I don't know exactly what kind of arm or pedal I should get. I have a trek 4300 2003 model. Here is the link to the bike: http://www.trekbikes.com/ca/en/bikes/2003/archive/4300
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Old 09-29-12, 07:44 PM   #2
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Pictures would help. Depending on how badly damaged the threads on the crank arm are damaged, you may be able to have them cleared with a tap (most bike shops can do this). If the damage is more serious than that, you can use a thread repair kit, as I recall, there's a company making them for bicycle pedal threads.
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Old 09-29-12, 08:01 PM   #3
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The most common variety of repair components are trademarked Helicoils; the hole is drilled and tapped oversize with a special tap and the Helicoil inserted with a special tool. Its driving tang is broken off and the repair is complete. The new threads will be stronger than the originals. A good bike shop should be able to make the repair easily and economically. The shop may possibly be able to provide a replacement pedal or you may have to buy a new pair.
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Old 09-29-12, 10:31 PM   #4
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Thats the best I could do with my phone's camera. When I was riding, part of the pedal broke of and i could see the pedal was bent from the arm. I tried riding a bit more so I could get back and eventually the pedal came off altogether.
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Old 09-29-12, 11:16 PM   #5
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Looks like you might need to replace the crank arm. Those threads don't look too healthy.
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Old 09-29-12, 11:17 PM   #6
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A bike shop could easily save that but if that is the left side crank on a square taper crankset it would likely just be cheaper (and easier) than having to both repair the threads and straighten out the crank arm.
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Old 09-29-12, 11:42 PM   #7
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It is the right side crank with the chain rings and as I mentioned above, the link to the trek website shows what kind of crank it is. I'll post pics soon. I think that if anything i should just buy new crank arms because the labor cost will be really high for something like Helicoils.
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Old 09-29-12, 11:50 PM   #8
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The bolt in there is hex in case you couldn't already see. Anyways, how do I know what kind of crank arm I need to get and what kind of pedals?
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Last edited by mkansari; 09-29-12 at 11:59 PM.
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Old 09-30-12, 12:18 AM   #9
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If the crank is not bent, it can probably simply be helicoiled. My bike shop charges $20 labor to helicoil the pedal threads in a crank. Much cheaper than replacing the crank. Pedals - whatever you want, the bike shop will have some that are fairly similar to the remaining left side pedal.
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Old 09-30-12, 11:08 AM   #10
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I'm having real trouble. I live in toronto and the LBS' here don't seem to do helicoil. Also they don't sell single driveside crank arms. Its gonna cost me around 80 bucks at least!!!!!! and I bought the bike for 130!!
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Old 09-30-12, 11:14 AM   #11
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Quote:
Originally Posted by mkansari View Post
I'm having real trouble. I live in toronto and the LBS' here don't seem to do helicoil. Also they don't sell single driveside crank arms. Its gonna cost me around 80 bucks at least!!!!!! and I bought the bike for 130!!
Look for a bike charity or bike recycling project. They have tons of this kind of stuff lying around.
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Old 09-30-12, 11:40 AM   #12
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Check Ebay
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Old 09-30-12, 11:41 AM   #13
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Car mechanic for the helicoil. Tell him it's 9/16" x 20tpi.
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Old 09-30-12, 11:56 AM   #14
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Quote:
Originally Posted by mkansari View Post
I'm having real trouble. I live in toronto and the LBS' here don't seem to do helicoil. Also they don't sell single driveside crank arms. Its gonna cost me around 80 bucks at least!!!!!! and I bought the bike for 130!!
If you can't find a mechanic to helicoil, you might be able to find a co-op or non-profit bike shop with a crank arm which will fit and transfer the chain rings. That would be my plan A if in your position. Otherwise, you'll be forced either to go to a bike shop, or the dreaded EBay. Make sure you know the BCD of your chain rings, it's a critical measurement.
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Old 09-30-12, 12:06 PM   #15
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Another repair tool kit, and so alternative repair technique , is a double threaded sleeve.
like helicoil, you ream and re-thread the crank arm,
then install the section of tubing that is threaded inside and out..

I suspect it was an operator problem, the pedal was loose but you rode the bike anyhow.
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Old 09-30-12, 12:08 PM   #16
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I suspect it was an operator problem, the pedal was loose but you rode the bike anyhow.
Calling the OP a liar?
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Out of nowhere this small POLE appears and my pedal smashes into it and snaps off.
Actually come to think of it, that would be more likely if the pedal was already loose... if it wasn't you'd have to whack it pretty damn hard, and I'd expect to see the end of the crank torn to crap.
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Old 09-30-12, 12:43 PM   #17
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The hole looks like it was distorted by a downward force, so unless the pedal was at 9:00
when the pedal hit something,
#1 your foot would be a bigger problem bruised or broken bones.
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Old 09-30-12, 12:51 PM   #18
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Calling the OP a liar?

Actually come to think of it, that would be more likely if the pedal was already loose... if it wasn't you'd have to whack it pretty damn hard, and I'd expect to see the end of the crank torn to crap.
Dudes, the drop was so steep my brakes couldn't help control the bike. I was going pretty fast and the pedal smashed into two pieces. I didn't even find the second piece
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Old 09-30-12, 12:52 PM   #19
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and its pretty much known that the cranks threading is not very strong compared to the pedal's
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Old 09-30-12, 12:54 PM   #20
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The hole looks like it was distorted by a downward force, so unless the pedal was at 9:00
when the pedal hit something,
#1 your foot would be a bigger problem bruised or broken bones.
Thankfully I was wearing shoes which had a twist/bend proof technology (various plastics around places prone to bending and twisting) otherwise I would have been at the ER.
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Old 09-30-12, 12:57 PM   #21
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I'm not sure what kind of arm would be appropriate, i.e. http://www.ebay.com/itm/Shimano-FC-M...item4843738d17. would this work?

Last edited by mkansari; 09-30-12 at 01:05 PM.
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Old 09-30-12, 01:55 PM   #22
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Dudes, the drop was so steep my brakes couldn't help control the bike. I was going pretty fast and the pedal smashed into two pieces. I didn't even find the second piece


Well, that would have loosened it...

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I'm not sure what kind of arm would be appropriate, i.e. http://www.ebay.com/itm/Shimano-FC-M...item4843738d17. would this work?
NFI - if you're only replacing the drive-side arm, there are three things to get right - chainring PCD, the relationship between the BB interface and the chainring mounting (required BB length), and the relationship between the BB interface and the pedal thread (Q factor? Hardly ever stated). Tough...

I reckon your best bet is prolly the helicoil. Or if you can find a local bike co-op or something similar, you should be able to replace both cranks for like $20 or less (then you don't have to worry about the Q factor).

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Old 10-01-12, 12:41 AM   #23
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ok I think I might buy a new crankset cuz I can't find anyone thats gonna do helicoil. How do I know what type of crankset will fit and whether it will be the same quality as this one.
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Old 10-01-12, 01:21 AM   #24
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ok I think I might buy a new crankset cuz I can't find anyone thats gonna do helicoil. How do I know what type of crankset will fit and whether it will be the same quality as this one.
For specifics on what you need, a post mentioned BCD, this isn't relevant if changing the complete crank, only chain rings, and for budget cranks, it is never cost effective to just change the rings.

You need to know the bottom bracket type your bike has, you most likely have Square Taper (you need to confirm this), the crank arm fitting must match your BB, the spindle length required for the crank should match as well. Also if keeping to the same gearing, you need a crank with 42-34-24 rings. You will also want to confirm the crank arm length, this will most likely be 175mm or 170mm.

Would be looking at something like a Shimano Alivio to be similar to the current spec of your bike, and should be pretty cheap. if you can spend a bit more, would be looking at a Shimano Deore M590 with HT2 BB (retail packs come with BB's), this would require swapping the BB for a different design (HT2), but eliminates most of the issues around matching sizes.
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Old 10-01-12, 01:31 AM   #25
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90% of cranks are 170s, but if you're over 5'10" or so, you might like to try 175s.
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