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Broken spoke and bent rear axle on MTB second time in a month

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Broken spoke and bent rear axle on MTB second time in a month

Old 10-09-13, 09:20 PM
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mmaaxx
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Broken spoke and bent rear axle on MTB second time in a month

Hi, as title says, I have broken spoke and bent rear axle second time within a month!

I'm riding cheap, department store dual-suspension MTB that is 8 years old. 95% of the riding - is paved or gravel recreational trails. I was riding it often first 4 years (~300 miles/season), then it was sitting in a storage. This season I resumed riding it, and put about 300 miles, before I had a broken spoke, bent axle and crushed ball bearing on the rear wheel. It happen on a plain, flat gravel trail.

I got new parts from LBS. Replaced everything, trued the wheel fairly well. and did another ~150 miles, when same thing happened again! With the exception that this time, the ball bearing survived.

I'm 6'2, about 270 (first 4 years that I ride it, I was 250).

I have few question, and really appreciate any help:
1. Why is this keep happening, and what gives up first a spoke or the axle?
2. How can I prevent it from happening?

Old wheels (there are little rust and corrosion on spokes)?
Out of true?
Too cheap axles/wheels to handle my weight?

PS: when I was removing freewheel 2nd time, I was holding a wheel by the tire, and broke one more spoke. should a wheel be able to handle such thing as freewheel removal, or should I really use a chain wrench?

Thanks!

Last edited by mmaaxx; 10-09-13 at 09:26 PM.
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Old 10-09-13, 09:29 PM
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BikeWise1
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If you are set on attempting to continue to use this bike, you need to spring for a decent double wall rim, built on a cassette-style rear hub. You can use a road hub on this bike given the rear dropout spacing is likely 126mm, rather than the current ATB standard of 135mm. You are too big for cheap replacement wheels, especially of the freewheel variety. A cassette hub will not have axle-breakage issues....

A chain whip will not help when removing a freewheel. And yes, it is common for tired wheels to break spokes during freewheel removal, especially the way you were doing it. The shop way is to put the tool in a well-mounted vise, put the wheel on the tool, pretend the wheel is the steering wheel of a bus, and you are turning the bus to the left. This will avoid side loading the wheel as much.
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Old 10-09-13, 09:32 PM
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You, like me, are a "Clyde." We're big and heavy, and if the rear axle (usually on the cluster side) is too long, then at our size, axles can bend and spokes can break.

Once spokes break and you get multiple spokes, then most likely, you're in a mode where more and more will break as the spokes have suffered fatigue stress and are like to continue to break.

You may want to get a better rear wheel with a true cassette hub where the cantilevered distance on the axle is shorter (i.e. the bearings are more outboard). Next, make sure the wheel has quality stainless spokes that are properly tensioned (i.e. they need to be tightened such that your weight, while riding never reverses the tension to compression on the spoke, which will flex the elbow near the hub and within 400 - 850 miles depending on quality of the spoke, will cause failure). You could go to a trusted LBS and pay decent money (not sure if your bike is worth that much). Or you might order the wheel online (if you can find one compatible with your bike's shifters/number of gears) and do the spoke tensioning yourself.
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Old 10-09-13, 09:42 PM
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mmaaxx
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Thanks guys! I got it. So on the cassette hub, bearings are close to a frame, which provides little "elbow". And on freewheel, one bearing is close to a frame, and other is at a freewheel depth from the frame (there is a spacer to make up for a distance). This makes a large elbow, and that's where the axle bents, which brakes a spoke.

I guess it's time to retire the bike, and get something new!

Thanks for replies!
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Old 10-09-13, 11:11 PM
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OH god, a clyde on a dept store bike. I'm sorry but I'm well over 300 pounds and my son is almost 300. When he first started riding about 3 years ago, he used my early nineties Huffy mountain bike that was in great shape (never rode it). He bent 2 axles, broke 1, bent up the rim, bent the rear frame, and overall just killed it quickly. No offense but a big guy like you should really look for a nicer bike. I bought a 50 dollar Speciallized Hardrock from CL and had great luck with it but ended up moving to road bikes.

The best kind of commuter bikes for big people are older brand name mountain bikes. I see tons of Trek 800 series mountain bikes from the eighties/nineties on CL for under 100 dollars all the time. They use strong freehub based wheels and are durable as heck. Same for older pre-suspension Specialized Hardrocks.

You can probably find a very solid durable rigid brand-name LBS mountain bike cheaply that will end up being MUCH nicer to ride. Put a nice set of skinnier slicks on it and they ride so nicely for big people.

IN a nutshell, dump any wheel that uses a freewheel. I donate all freewheel wheels I get to my co-op since they aren't nearly as durable.
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Old 10-10-13, 07:51 AM
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Originally Posted by mmaaxx View Post
makes a large elbow, and that's where the axle bents, which brakes a spoke.
spoke breakage has nothing to do with bent axle
spokes can fatigue over time from normal riding
and your spokes are almost definitely at the end of their life

it is just a coincidence that spokes and axle are failing at the same time
the only common factor is an extra large rider
which will put more stress on parts

when you shop for a new bike
get a rigid one
or one with just front suspension
with a cheap full suspension bike
you are paying more for the suspension mechanism
and less for quality components

although
any bike you get with a freewheel
will have bent axles over time
it is an outdated and insifficiently strong design
here is a guide on how to tell a freehub from a freewheel
in case you are shopping for a used bike

also
if you are six foot two
department store bikes
are likely too small for you
a used bike shop quality bike in the 20 to 22 inch frame size
will likely allow much more comfortable riding
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Old 10-10-13, 08:34 AM
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mmaaxx
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Thanks for suggestions. I was looking for something nicer since beginning of the season, was waiting for post-season sales at LBS, but it seems like there will be not much of a sale.
I'm looking to get TREK FX or DS. Mostly looking at DS, as I'm afraid that FX has weak wheels (less spokes), and I'll keep breaking them.
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Old 10-10-13, 11:49 AM
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Wilfred Laurier
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Originally Posted by mmaaxx View Post
I'm looking to get TREK FX or DS. Mostly looking at DS, as I'm afraid that FX has weak wheels (less spokes), and I'll keep breaking them.
this is not true
the fx series
up to 7 point 4 or 7 point 5
has 32 spokes
same as the ds bikes

the real advantage of the fx bikes
is that they have rigid forks
instead of the basic suspension on the ds
which will likely be unable to hold up the weight of a larger rider
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