Bicycle Mechanics - 2 cranks in 1 month...

I bought a bike from a department store and so far I have been having nothing but problems. The crank on this bike broke within a week of purchasing the bike.. the left side of crank has became completely loose .. so loose that when you pedal it does not go in a perfect circle, so I gave it in for repairs and got it back the next week. They gave me a Shimano (I think thats how its spelled) crank and told me it shouldn't give me any problems. Well .. today I have the exact same problem, the left crank is completely loose.

I have been thinking a lot of why this is happening and I am having a doubts that the parts of these cranks are failing naturally. I am about 6'4" at 205lbs, and I tend to ride my bike standing/not-sitting throughout the trip. I ride in the city (on the sidewalks and bike trails through parks), and the whole trip lasts about 45 minutes. I figure that my leg muscles would be worked a lot more if I force myself to stand instead of sit down, and because of this I believe that the cranks keep breaking. Has this happen to anyone? Also .. is there a crank specifically meant for riding your bike standing or do I have to change the way I ride my bike?

Thanks for your time!

I bought a bike from a department store and so far I have been having nothing but problems. The crank on this bike broke within a week of purchasing the bike.. the left side of crank has became completely loose .. so loose that when you pedal it does not go in a perfect circle, so I gave it in for repairs and got it back the next week. They gave me a Shimano (I think thats how its spelled) crank and told me it shouldn't give me any problems. Well .. today I have the exact same problem, the left crank is completely loose.

I have been thinking a lot of why this is happening and I am having a doubts that the parts of these cranks are failing naturally. I am about 6'4" at 205lbs, and I tend to ride my bike standing/not-sitting throughout the trip. I ride in the city (on the sidewalks and bike trails through parks), and the whole trip lasts about 45 minutes. I figure that my leg muscles would be worked a lot more if I force myself to stand instead of sit down, and because of this I believe that the cranks keep breaking. Has this happen to anyone? Also .. is there a crank specifically meant for riding your bike standing or do I have to change the way I ride my bike?

Thanks for your time!Mignt it also be reasonable to suspect the nose pickers aren't installing them right?

I bought a bike from a department store and so far I have been having nothing but problems. The crank on this bike broke within a week of purchasing the bike.. the left side of crank has became completely loose .. so loose that when you pedal it does not go in a perfect circle, so I gave it in for repairs and got it back the next week. They gave me a Shimano (I think thats how its spelled) crank and told me it shouldn't give me any problems. Well .. today I have the exact same problem, the left crank is completely loose.

I have been thinking a lot of why this is happening and I am having a doubts that the parts of these cranks are failing naturally. I am about 6'4" at 205lbs, and I tend to ride my bike standing/not-sitting throughout the trip. I ride in the city (on the sidewalks and bike trails through parks), and the whole trip lasts about 45 minutes. I figure that my leg muscles would be worked a lot more if I force myself to stand instead of sit down, and because of this I believe that the cranks keep breaking. Has this happen to anyone? Also .. is there a crank specifically meant for riding your bike standing or do I have to change the way I ride my bike?

Thanks for your time!
You're a big guy, but not that big. I weigh in around 200#. Like sydney alluded to, the department store guys didn't install the crank correctly. Most likely not torqued to specifications when first built.

May I make a suggestion. If you can get a refund for your dept. store bike good, try to get it. If not, write off the cost to experience with inexperienced people. Then find a good bike shop that you feel that you can rely on, tell them of your experiences, tell them how you like to ride and see what they have to offer. I would guess that the cost difference between the dept. store bike and the bike shop bike might not be that great. And with a good bike shop, you are dealing with experienced folks who hopefully will do you good.

I bought a bike from a department store and so far I have been having nothing but problems. ... An entirely normal outcome for an unfortunate decision on your part. I am sorry to be the messenger of bad news and to come across as a jerk, but your bike is junk, and it was probably incorrectly assembled and adjusted.

I appreciate the input so far .. I am having the same thoughts about the bike as well. I am surprised to hear that the way I ride the bike isn't the problem (at least no one mentioned this .. yet?).

As for the bike, well .. I guess I am stuck with this one for awhile. I'm still a student at a college and buying another bike would be very difficult for me (especially one thats over $200CDN). As for refund, the store I bought it from (Canadian Tire) never informed me about their very stupid refund policy, where they accept refunds from any product but bikes.. I had complained to this to the head office but it was a bunch of idiotic business politics which never would get me anywhere (soon at least).

I was ignorant when buying this bike, I never thought bikes would be like cars where some companies don't know how to build them and some do. Ahh well .. s**t happens.

A little fyi, the bike is an 18 speed Supercycle bike with 20" rims..

Again .. I appreciate the replies so far! Thank you...

I appreciate the input so far .. I am having the same thoughts about the bike as well. I am surprised to hear that the way I ride the bike isn't the problem (at least no one mentioned this .. yet?).


Your riding style might not exceed the capabilities of a bike of reasonable quality. It does apparently exceed the quality of the chinese components installed on your bike.

This won't be the most expensive lesson you learn in the next 5 years so don't sweat it too much.

Been there, done that many times ;)

Your riding style might not exceed the capabilities of a bike of reasonable quality. It does apparently exceed the quality of the chinese components installed on your bike.

This won't be the most expensive lesson you learn in the next 5 years so don't sweat it too much.

Been there, done that many times ;)

heh .. appreciate the input.

I appreciate the input so far .. I am having the same thoughts about the bike as well. I am surprised to hear that the way I ride the bike isn't the problem (at least no one mentioned this .. yet?).

As for the bike, well .. I guess I am stuck with this one for awhile. I'm still a student at a college and buying another bike would be very difficult for me (especially one thats over $200CDN). As for refund, the store I bought it from (Canadian Tire) never informed me about their very stupid refund policy, where they accept refunds from any product but bikes.. I had complained to this to the head office but it was a bunch of idiotic business politics which never would get me anywhere (soon at least).

I was ignorant when buying this bike, I never thought bikes would be like cars where some companies don't know how to build them and some do. Ahh well .. s**t happens.

A little fyi, the bike is an 18 speed Supercycle bike with 20" rims..

Again .. I appreciate the replies so far! Thank you...


Get yourself a good manual & basic set of tools. Go over all the fasteners on the bike, starting with the cranks. Learn how to adjust your own brakes, deraillers, etc. If you don't want to buy a book, rent one at the library and/or use the internet resources like bikeforums, sheldonbrown.com and park tools website. You might consider riding seated too, but if you're not jumping the bike the cranks should hold up to the load. Make sure they're installed properly next time you replace the crank arm. Consult resources listed above to make sure it is installed properly. Consider finding yourself a sucker to sell your bike to, which you will replace with a quality used bike.

I bought a bike from a department store and so far I have been having nothing but problems. The crank on this bike broke within a week of purchasing the bike.. the left side of crank has became completely loose .. so loose that when you pedal it does not go in a perfect circle, so I gave it in for repairs and got it back the next week. They gave me a Shimano (I think thats how its spelled) crank and told me it shouldn't give me any problems. Well .. today I have the exact same problem, the left crank is completely loose.

I have been thinking a lot of why this is happening and I am having a doubts that the parts of these cranks are failing naturally. I am about 6'4" at 205lbs, and I tend to ride my bike standing/not-sitting throughout the trip. I ride in the city (on the sidewalks and bike trails through parks), and the whole trip lasts about 45 minutes. I figure that my leg muscles would be worked a lot more if I force myself to stand instead of sit down, and because of this I believe that the cranks keep breaking. Has this happen to anyone? Also .. is there a crank specifically meant for riding your bike standing or do I have to change the way I ride my bike?

Thanks for your time!

I had the same problem until tightened after every ride about 6 times, then just tightened them once in a while, no more problems even though in the beginning one crank fell off. They are square taper.

Not to belabor the point, but I remember watching the guys assembling bikes at a Sports Authority in Atlanta; they were using air-fed impact wrenches for just about every part on the bike!

Need I say more..?