Leonard4

First time poster here, long time lurker! Thought i'd see about borrowing from everyones expertise and get some advice on a problem i've been having for awhile. I picked up a Columbia 21 Speed from Amazon about a year ago, standard fare $300 special. Hardtail setup, with a shock in the front, has disc brakes, which I'm told is rare on a bike this "cheap". Anyways I've ridden for about 6-7 months now, about 5 times a week, for ~15 miles each day and the bikes been great, with zero problems. About a month ago the rear tire has started to "drift" to the left when i pedal, when i crank it will flex and rub the inside of the frame on the left. So I pulled the back rim off, and spun the axle and it was clearly bent, I had a local shop replace it who said the axle was bent, and within 3 days of riding, it was back to how it was. So i wondered, did they really fix it? I rode this bike for 7 months without a problem. I took it to another shop, they replaced the axle again and this time said it was actually broken, and replaced my bottom bracket as well as the threads were stripped on one side. Four or five days later, its just as bad as it was before, and even worse now, I can see what looks like a washer or cover for the bearings has broken, and has a huge cap between the bearings and the cup, almost wide enough for the bearings to fall out, the wheel is compeletely unridable.

The guy at the shop said it wasn't a bad bike, and for the price it was a good ride if maintained correctly, which I've done. I'm not offroading, or trail riding, this is strictly street/paved pathways i'm riding on, but large mileage each day (15-20 miles) so i don't understand why it would continue to break like this after so many months of flawless riding. I'm afraid that that if I get the axle replaced again, its just going to keep doing this, which doesn't make any sense to me. Has anyone had a similar experience with a rear axle failing like this, or have any recommendations on what to check for or do to fix this? I'm dead in the water and with summer coming i need my ride back!

DannoXYZ 

If you can post a picture, that'll help us diagnose.

Breaking rear axles is a common problem on 7-speed freewheel hubs. The large distance between the right-side bearing and dropout causes a lot of bending stress on the axle and it bends and/or brakes. The bearing-cap falling out is a sign of an axle that's wobbling; probably broken again.

Best to get a freehub rear-wheel. The right-side bearing is closer to the dropout to reduce the bending moment.

BTW, is it a quick-release hub or bolt-on?

Retro Grouch 

Without looking at your bike I'm wondering if the original bent axle also bent the dropouts to match. Consequently, every time that you feed a new axle to the bike, the bent dropouts reform the axle until it fits them again.

Better than average bike shops will have a gauge for checking dropout alignment. It looks like two big mushrooms that bolt into the dropouts. When the two mushrooms line up perfectly with one another, the dropouts are parallel.

Leonard4

Its a quick release hub, the skewer gets bent to where it doesn't roll straight as well. One of the guys at the shop actually explained that exact thing, to where the distance between the right side bearing and drop out were larger than that of a "normal" bearing setup hub/wheel. Sounds like i need to stepup to a new freehub rear wheel, and like Retro said check the dropouts to make sure they aren't bent as well. Hopefully that will fix everything, thanks for the assistance.