Bicycle Mechanics - 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

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.

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.

275604275605275606275607275608Thats 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.

Looks like you might need to replace the crank arm. Those threads don't look too healthy.

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.

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.

275619275620The 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?

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.

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!!

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.

Check Ebay

Car mechanic for the helicoil. Tell him it's 9/16" x 20tpi.

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.

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.

I suspect it was an operator problem, the pedal was loose but you rode the bike anyhow.
Calling the OP a liar?
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.

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.

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 piece275701

and its pretty much known that the cranks threading is not very strong compared to the pedal's

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.

I'm not sure what kind of arm would be appropriate, i.e. http://www.ebay.com/itm/Shimano-FC-M440-L-Right-Hand-Crank-Arm-170mm-Black-/310369291543?pt=Cycling_Parts_Accessories&hash=item4843738d17. would this work?

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 piece275701

:eek:

Well, that would have loosened it...


I'm not sure what kind of arm would be appropriate, i.e. http://www.ebay.com/itm/Shimano-FC-M440-L-Right-Hand-Crank-Arm-170mm-Black-/310369291543?pt=Cycling_Parts_Accessories&hash=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).

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.

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.

90% of cranks are 170s, but if you're over 5'10" or so, you might like to try 175s.

Two similiar vintage Trek 4300's passed through my hands recently. The oem cranks are low grade stamped steel chainrings, heavy and rust prone. Get yourself a used triple mtb set of aluminum cranks, square taper, with aluminum chainrings. I think the spacing and size of the rings don't vary that much. FSA, Coda, Sugino, or Shimano will all work. I've bought used Shimano Deore for abiut $40, including shipping on ebay. Get some new pedals too! You can buy a crank puller for $15 and do the work yourself in less than thirty minutes or go the coop and get help. Detailed instructions can be searched on this forum.

http://www.bikeforums.net/image.php?u=305894&dateline=1339030849

Heh... that's av + handle win : )

Pity someone beat you to it ; )

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!!Call around some more, this is actually a repair that shops can handle. It's not a very common thing like flats, but still occurs often enough that they're familiar with it. Problem is having the staff with the skills to do things like this. Ends up being a major liability issue and a lot of shops in the U.S. simply won't do it. May be easier to find in a less litigious area.

Anyway, Helicoil is the bottom of the line repair. Recoil, Permacoil are other brands that makes wire-insert repairs. A double-threaded solid insert is much stronger and longer-lasting. These repair-kits are made by VAR and Unior/Eldi (German). The tap for the Unior kit is a marvel. It has a long guide before the cutting teeth that fits tightly into the hole to ensure the threads are started at exactly 90-degrees to the crankarm. You wouldn't believe how many Helicoil repairs ends up with slanted hole & threads. :(

http://www.bikeforums.net/image.php?u=305894&dateline=1339030849

Heh... that's av + handle win : )

Pity someone beat you to it ; )

It's hard to keep the hat from flying off at high speed!:thumb:

Those hats can be deadly... hope you don't live in a litigious area ;)

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.
I think its square taper.276017

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.Well, in this case, the chainrings have an oddball 6-bolt on 4-arm spider. Looks like they're riveted on as well. If he can find a shop to repair the threads for $20 or less, it'll be worth it. Otherwise a used crankset with replaceable alloy chainrings for $40-50 will end up being twice as good as the one he's replacing.

I'm going to post some more pics of the crank

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