ClydeClydeson

So it's the left, or non drive side (NDS). A replacement arm should be around $10.

However, since it is a steel crank it is likely that the spindle tapers are also damaged. Even if imperceptibly damaged, a new crank arm might just loosen off and cause the whole cycle to start again.

ClydeClydeson

PS:

You pedal has a 9/16" spindle, which is the standard size for all cranks with separate spindles and arms. Whatever crankset you get will work with those pedals.

Litespud

How do you figure it's a steel crank? The pic above shows that it's well chewed up- way more so than the spindle, suggesting that it's Al. In any case, it's toast.

ClydeClydeson

I could very well be wrong. But the clues that make me think it is steel are the thinner-than-expected area around the taper and the overall thin profile. Also the fact it is off a very low-cost bike.

Anyhoo, the spindle is likely much harder steel than the arm, even if it is steel, and the damage to the arm would not be unusual if you did as OP was suggested and loctited the nut on and kept riding..

Also, riding with a damaged alloy crankarm can also cause damage to a spindle. I don't know if it would be debris or just the oxide layer of the Al acting as an abraisive, but I'd bet dollars to donuts that any new crankarm is also going to eventually loosen off if installed on that spindle.

sovende

Moot point but a magnet will quickly solve the “is it steel or is it aluminum (aluminium for some ). Before throwing too much time, effort and most importantly, cash at this bike, I’d start searching for an entire bike upgrade . Initially, I questioned the 152mm crank length but since the OP included the link to the product he’s buying, I guess that they do exist. Seems awfully short to me. I’m obviously not knowledgeable as to the full range of available crank lengths. May have to go back and actually have a look at the bike he has to see if there’s a reason for short cranks.

Troul 

odd that it has worked fine for me.

ClydeClydeson

If you've had to do this repair more than once on your own bike then I don't think you should be advising anyone on any bike repair subject. If you knew what you were doing you wouldn't have a damaged crankset in the first place.

Litespud

I agree - I think at this point the OP would be better off getting a new crankset and BB, and starting with a clean (and properly torqued!) slate

base2 

I'm quoting myself from post number 17. You may try here. I think a whole wheel once cost me, like $30 after shipping.

dabac

I can just about promise that your pedal thread is 9/16”.

dedhed

Honestly, by the time you purchase the parts and tools required, you'd be better off just buying the same bike or similar new. If available.


https://www.walmart.com/ip/Roadmaste...black/55376950

https://www.walmart.com/ip/Roadmaste...lack/121263262

Troul 

The OP, likely is due for some new parts as the hardware seemed to reach a plastic zone. At this point, the OP might achieve a final use of the current parts should they option for using loctite red. If the loctite red does not hold, there's no loss in trying to extend the expired life of the hardware. If it does hold, the OP can use the extension of time to come up with another plan with what they'd like to do. That plan would be imo, replace the old parts with better, or N+1.

Regarding my use of loctite red with a bicycle; It was to put an old bicycle to use without expecting longevity. Cause of issue, IDK, not aware of its past. It surprisingly worked longer than expected. So well in fact, that instead of donating the bicycle to the local garbage truck; new parts were bought to replace the parts that contained loctite red.
I bet the kid I gave it too got a lot of use out of it.

crcook84

I think I'll just go ahead and buy another crank arm. Even if the spindle is damaged, I can use it until it fails entirely. By then, I should be in a financial position to be able to take it into a repair shop and they can professionally assess the condition of all the parts and determine if anything needs to be replaced. Otherwise, we have another bike. It's just that the spare bike is a 26" while my bike is a 24", which is more comfortable.

sovende

$15 is not too much to replace the NDS crank but I’m afraid you’re just wasting $$! Waiting “until it fails entirely” may result in costs not measured in dollars i.e. personal injury!!! Since it seems that you will be “fixing” your current problem, IMHO, make sure that the replacement crank is properly fastened to the spindle! To me, that means thoroughly cleaning the mating surfaces of the spindle and the crank arm. Don’t apply any lubricant to the mating surfaces. Borrow a torque wrench from someone (I suspect you don’t have one but if you plan on “wrenching” on bikes, I’d get one. They’re relatively inexpensive at Harbor Freight) and apply at least 30ft-lbs of force to secure the retention nut.
You mentioned that your “favored” bike with the 24” wheels is more comfortable. You must be fairly short in stature. Perhaps you could post a pic of you straddling your bike. We’re here to help

crcook84

sovende

Thanks for the pic! I have to say that bike looks a little too small for you BUT if that’s what gets you riding, so be it 👍. If you ride regularly, I believe that you’ll be wanting to move up to your bike with the larger wheels (26”) and larger frame. That, of course, will be up to you. Working on/fixing on your preferred bike will provide you with the experience and confidence to be able to work on the other bike that will hopefully become your preferred ride 😎.

crcook84

So, update: I know I haven't said anything since my last post....almost a month ago. Well, I live in Texas....'nough said. The crank arrived probably 2/11 or 2/12. I applied the Locktite and was going to give it till Sunday to cure. Mind you, I wasn't keeping an eye on the weather. Had to wait a week or two for the snow to melt and the temperature to warm up enough before I could try bicycle riding with the repair work. She works smoothly. With a few posts commenting that I need a bigger bike, I did bring the seat up a few inches. I feel like that helped my peddling. More comfortable.

UniChris

If it stays on it's because you got the tapers to mate, NOT because of the locktite, which was a terrible mistake to repeat.
If the tapers aren't mated then the crank will work loose as they wear even while the locktite keeps the nut from moving.

Keep your ear out for any sort of creaking sound while climbing, as with a steel crank that can be an earlier sign than any perceptable movement though you might not hear it over the drivetrain.

If you hadn't used the locktite you could check after 100 miles to see if the nut was still holding the tapers but now all you'll feel through the wrench is the glue.