smessvader

I switched out my pedals on my (new!) Specialized -- with Tiagra crankset -- and the right pedal felt particularly hard to attach. Plus, when I took it for a ride, I could tell that the pedal was uneven. I took it home, and as expected, I had misinstalled the pedal, and the crank arm was stripped -- but not entirely. I was able to wrench it out, and reinstall it correctly -- it attaches fairly securely, but it just won't tighten all the way at the end. I took it for another spin, and it felt okay to pedal -- how worried should I be? Should I continue to ride it if I don't really think there's a danger of it disconnecting, or do I need to fix this asap? Is there a way to fix this without replacing the whole crankset (oh no!!). I plan to call my LBS tomorrow, but wanted to get some advice from the group. Thanks!

grolby

You need a new crank. End of story. It's probably not going to stay in place for long. If it's the right, you might have a problem - I'm not sure separate right cranks are typically sold. Your LBS might be able to order you one. Next time, be more careful when installing your pedals. Oh, and it's relatively safe to ride, but you might find the pedal coming loose at an inopportune moment, which could send you to the deck rather abruptly if you're out of the saddle. I would fix it without delay, that's the safest thing to do.

fauxto nick

New crank, or try and find a machine shop to tap and die it, but i'd say ebay a new set of tiagra cranks.

bhikkhu

It probably could be fixed, but even a helicoil insert would be a weak point. I bought a new (take-off) Tiagra crank on Ebay last summer for $50, and there was no shortage then. That should be cheaper than a machine shop anyway.

fogrider

yeah, you don't want to have it fail when you're 30 miles into a long ride...get another crank.

datlas 

+1 for new crank. You might be able to get a single side, used, on the cheap from Ebay.

One other thing: FORGIVE yourself!

Most of us have done similar things and I, for one, have beaten myself up mentally about it. Stuff happens, get a new crank and be extra careful in the future when threading your pedals.

stedalus

Before replacing it, I would first take it to a bike shop and have them chase the threads with a pedal tap. (A machine shop probably won't have the proper taps for this.) This will take away some material, but typically there is still plenty of thread engagement remaining. If not, then a new crank is in order.

Brian Ratliff

A helicoil in aluminum might result in a broken crank a la PCad. Apparently helicoils are a fairly large stress riser.

I'd just take it to the bike shop to chase the threads. As long as the threads aren't too munged up, it should be fine.

celerystalksme

you need new crank arm...

crank arms are usually sold together, left and right...as a unit. BUT...i have found just left or just right on ebay. so look for used stuff being sold like that.

or use this as an opportunity to upgrade...get a nice new crankset...

smessvader

Thanks for all the advice. I took a look this morning, and realized that the pedal was more wobbly than I first thought, so I am taking it to the LBS today to see if they can work some magic rather than having to buy a whole new crankset.

But thank you too for the encouraging words! I have indeed beat myself up for maiming my beloved brand new bike, but I take your words to heart -- we have to learn some lessons the hard way, and it's better to learn earlier rather than later that bikes are fragile and I need to be more careful in my future role as an amateur wrench.

ptle

I had the exact same problem. The last three threads on my crank arm was stripped. I put the pedal back on as a temporary fix, but it ended up becoming loose again. Your best bet is to replace the crank set or get a helicoil, though I would recommend a new crank.

My old crank was a triple Tiagra. I scored a pretty good deal from bonktown.com on a double 105 crank. Even though my bike was nine speed, and the crank was ten speed everything worked out. This could be a chance for you to swap to a double if you don't need the triple. I did and it shaved some weight off my bike (I think).

stedalus

Fragile is maybe not the right word, but there are parts of a bike that can be ruined if you aren't careful when you work on them.

Some practical advice: when threading anything, use your hands only (no tools) for several revolutions to make sure you're not cross threading and that the threads are clean. If you feel significant resistance, clean out any dirt with solvent and a brush, regrease, and try again.