Bicycle Mechanics - Screw on Cluster bending axle?

I've bent the rear axle on my cheap a$$ MTB that I use for going to skool for the third time and I took it to a bike store with some really good mechanics and they reckoned first of all that im a "munter" on my bikes (My road bike hanger broke cause I crashed it etc etc) and that the fact that I have a screw on cluster and something in my riding technique, means that the axle keeps bending....they say that a cassette version of the wheel will solve everything?

Any comments?

Brendon
:beer:

Brendon,
It is quite true that a hub with screw on freewheel is more prone to bent axles than a freehub/cassette setup because of the way they are designed. On a freewheel hub the driveside bearing is set in close to the center of the axle, leaving quite a bit of unsupported axle extending out to the dropout. On a freehub the drive side bearing is out closer to the dropout so the axle has better support.
Regards,
Raymond

Because it took a matter of about two weeks of riding (152km) to school for it to bend.....must be the high power sprints between lights, and the really bad joints on the local bridge :p

But why does it happen to me and not my brother with the exact same bike? If it is my technique, how is that?

Brendon
:beer:

If you do a lot of rough riding or jumps down curbs that puts more stress on the axle.

Is this the bike you broke the derailleur hanger on? If it is, I'm betting you bent the dropout too. When that happens, when you clamp the rear wheel into the dropouts, it bends the axle.

Better bike shops will have a gauge that looks like two big mushrooms that clamp into your dropouts. You screw the mushrooms toward each other. If they line up, the dropouts are straight. If they don't, the mushrooms give you something to grab so that you can tweek them back into place.

Nah the hanger that I broke was on my road bike. I avoid drops etc like curbs....I stay on the road and thats it.

Brendon
:beer:

I think I would listen to Spoke Wrench, I can't tell you how many times I've seen bent dropouts do this.

I've seen bikes come straight out of the box with this problem (very rare, though) so it may not have been your fault.

Good riding

how reliable is the tweaking the dropouts back into place?

Brendon
:beer:

I didnt think that I would have to, but I am officially resurrecting this thread. In the end I ended up getting an entire new rear wheel (cheaper than replacing the hub) as the bent axles had caused some damage to the bearing races etc. Well I have hardly used the bike since, been using the RB, and I go and pull it out of the shep last night and I though I would check the bearing tightness etc cause there was a small amount of play. Well lo and behold the damn axle is bent again, on the new wheel. So I am thinking the dropouts might be misaligned (My dad seems to think this aint the possible cause....lol), or it is in fact something to do with my riding technique that everyone seems to keep repeating to me.

First of all I am a spinner, and maybe once or twice a day do I get out of the saddle etc. I am always spinning, even up the steep hills. (Triple Crank). How ever is it possible the way that I power away from intersections in the saddle the cause of my problems? I start off in low 4th, move off fast, and change under load to med 4th, then under load again to high 4th before using 5th etc.

HELP plz! I really want to ride the MTB to school and try and suss out the pain I was getting.

Brendon
:beer:

Axles come in crappy steel or cromoly steel. Use the latter for a stronger axle.

Brendon are you trying to tell us your legs are to strong for your low end bike ?? :D What make is it ? Put some pebbles in your shoes to discourage your powerfull pedaling :cry:

Avanti Tarini.......Tarini used to be a company before Avanti bought them out and started using the name for a model of bike......

Brendon
:beer: :love: for marie ;)

hey wait.....I was on Marie's computer and I didnt realise it had signed her in....I just saw the reply box at the bottom of the page and posted lol

Brendon

I would recommend switching to a good bmx bike with 48 spoke rims and 14mm solid steel axles.

I'd hate to say... when you get a new wheel, make sure they don't sell you one with a broken axle. Remove it and try to twist both ends. BTW, it might pay to check with a different bike shop.

Is your new wheel a wheel with a freehub or with a freewheel? I seriously hope that you got a wheel with a freehub. See there http://www.sheldonbrown.com/k7.html for a description of both types of wheels.
The freehub is stronger and cassettes are also easier to remove than freewheels, which is a good point if you are touring.

The fact dropouts are (could be) misaligned is a minor factor, especially if you have a freehub (it's a bit more serious with a freewheel). Basically, if they are seriously misaligned, you are "twisting" the axis when you squeeze the quick release. To see if you have a problem, place the wheel between dropouts and look at how the dropouts look. Normally, the bolts and quick release should apply evenly all around into the dropouts.

Other things to check: is the wheel well tensioned? Normally, you should be able to ping the spokes and they should be tight enough to play music, sort of. Loose spokes mean your wheel doesn't absorb road shocks the way it should.
In the same vein, what tires are you using and at what pressure? On a road bike with 700x28 or 700x32, you should have about 100 psi. On a MTB or hybrid with 26" x 1,75" or 2", you should have 60-80 psi, (I think). Check with what's written on the sidewall. Too soft tires are prone to pinch flats, but they also don't absorb shocks as well, which means your wheel (and axis) takes the blunt of it.
In the same vein, if you weight 300 lb, for example, you will be better with relatively wide tires (say 2.25"-2.5").


Riding technique also plays a role. Spinning is the best, not only for your knees, but also for the bike. Standing on the pedals, and especially trashing the bike from one side to another like they do in races is very hard on the bike and especially on the spokes (esp. with a loaded touring bike). So you're OK on that aspect.
However, you should get off the saddle when there is a bump, good pothole, nasty expansion joint, etc. By just getting a few centimetres off the saddle, the bike "rolls" on the bumps, so it's much easier on its mechanics. It will also be easier on your butt. Likewise, you could try to bunnyhop potholes and the like.
Keep also an eye on the road; try to avoid the worst places or, at best, take them slowly.