Broken rear axle

[RIPPERTON]

Have you ever broken a rear axle? How many ? and why do you think it broke? Ive busted 4 in my cycling life (since 8 years old). I think its mostly from using too high a gear and dont usually find out it broken till I go to remove the rear wheel for something else like a flat tire.

 

[Intheloonybin]

I think mine are from power. (no to be all hoity toity or anything )

When I raced, I bent a Campi C record crankshaft.

Just broke the rear axle on my mountain commuter, and I never ride off of curbs or roughly.

I could be wrong however...

 

[CAMPYBOB]

I broke a Campy Record rear axle years ago. It broke cleanly at the cone threads. The quick-release skewer held everything together, but the wheel wobbled badly. There was no thought of riding it back to the car/home; The wheel rubbed the brakes and the chainstays badly.

I believe the cause was from routine abuse during racing/training such as jumping railroad tracks and slamming potholes, etc.

 

[gclark8]

Seen one in a Mavic wheel, sealed bearings, QR type, fitted a BMX nutted axle with the same thread.

 

[garage sale GT]

I mostly used to ride low-end bikes. Those axles will bend rather than break. I cracked a bearing ball clean through after hitting a storm drain but the axle was just bent.

 

[RIPPERTON]

Ok seems this is not a common problem, BUT I fixed it anyway. Get a 22mmO/D 10mmI/D sealed ball bearing and install it on the axle so it lines up with the outer edge of the cluster. The bearing will fit snugly (light push fit) into the special socket castlation used to remove the gear cluster (this is a shimano hub btw) Juggle the spacers and lock nuts around so the bearing sits in the right position. (Photo)
What this does is transfer pedaling and load forces directly to the frame and not through the centre of the axle (where the cone is) in a leverage.

 

[John M]

Have you ever broken a rear axle? How many ? and why do you think it broke? Ive busted 4 in my cycling life (since 8 years old). I think its mostly from using too high a gear and dont usually find out it broken till I go to remove the rear wheel for something else like a flat tire.

Back in the pre-freehub days, this was more common. Freehubs place the load farther out on the axle towards the dropout so less torque on the axle at the point where the picture shows--which was the common point of breakage.

Your solution makes it even farther outboard.

 

[alienator]

Right now I'm using wheels with large diameter unidirectional boron fiber axles. I don't expect 'em to break.

One winter, I did break the axle on Mom and Dad's Cordoba when I slid off the road, 'cuz of ice, into a ditch.

 

[garage sale GT]

Ok seems this is not a common problem, BUT I fixed it anyway. Get a 22mmO/D 10mmI/D sealed ball bearing and install it on the axle so it lines up with the outer edge of the cluster. The bearing will fit snugly (light push fit) into the special socket castlation used to remove the gear cluster (this is a shimano hub btw) Juggle the spacers and lock nuts around so the bearing sits in the right position. (Photo)

I concur with JohnM, except it looks like you may have one of the lower end bikes which still comes with a freewheel. 7 speed rear? Dead giveaway on a new bike.

I believe that road shocks are by far more important than pedaling force, but that's just my opinion.

I had the same idea but the older bikes I favor typically come with a 3/8"/9.5mm solid axle. Your Shimano freewheel has 22mm splines but not all do. Some fw's don't even go on with splines and the bore which the outside of the bearing would go on is not very evenly finished, just roughly broached out.

I think running a bit of preload on the bearings as well as avoiding big bumps goes a long way toward axle longevity.

BTW you can buy solid 10mm axles if you want more strength.

 

[RIPPERTON]

I concur with JohnM, except it looks like you may have one of the lower end bikes which still comes with a freewheel. 7 speed rear? Dead giveaway on a new bike.

I believe that road shocks are by far more important than pedaling force, but that's just my opinion.

I had the same idea but the older bikes I favor typically come with a 3/8"/9.5mm solid axle. Your Shimano freewheel has 22mm splines but not all do. Some fw's don't even go on with splines and the bore which the outside of the bearing would go on is not very evenly finished, just roughly broached out.

I think running a bit of preload on the bearings as well as avoiding big bumps goes a long way toward axle longevity.

BTW you can buy solid 10mm axles if you want more strength.

pedaling force (especially in lower gears like 7th) exert more force on the axle than the load of your bum on the seat because of the leverage created by the chain being further out towards the frame plus the chain loads only the left bearing. The spokes exert force directly in line with BOTH bearings not just one.
The fact that I cant replace an inner tube on the side of the road without carrying a 15mm ring spanner with me means I cant run a solid axle. I actually had a spare solid axle in my bits box.
I no longer have to spend $20 on a chromoly axle every 8 months. The axle I fitted to my roady cost $10 and I know Il never break it. The only thing stopping me breaking a conventional axle due to a bad design is the brute strength of a high grade steel. Now the forces on my axle are reduced I dont need brute strength.
I just retrofitted a bearing to the chromoly axle in my Mountain bike this morning wich I installed 3 months ago after another breakage.

 

[garage sale GT]

Although my rough calculations indicate chain tension can be in the neighborhood of 1,000lb if you stand on the pedals and have the upper body strength to hold your torso steady as you push, I am still suspicious that sudden unexpected drops can cause even more force especially when you bottom the rim out on some edged obstacle.

 

[artemidorus]

I agree, it sure as anything is not your pedalling force breaking those axles, but rather the sharp loads from big bumps.

 

[RIPPERTON]

maybe you guys need to pedal harder


I think these breakages are a combination of me weighing 100kg plus being an ex ski bum have rather agro quads. I ride 40 km of Sydney traffic a day to work and sometimes have to get out of the way of things.

 

[garage sale GT]

maybe you guys need to pedal harder


I think these breakages are a combination of me weighing 100kg plus being an ex ski bum have rather agro quads. I ride 40 km of Sydney traffic a day to work and sometimes have to get out of the way of things.

I'm sure you realize the load is only equal to your weight if you are standing still.

Don't you ever bottom your tire to the rim? I guessed a tire bottomed to the rim is shaped like an ellipse and measured 1.75X10" on my 27X1-1/4 Panaracer, giving an area of 13.7 square inches, so compressing half the contact patch to the rim, such as what happens when you hit something like the far edge of a pothole, requires (13.7/2)x90psi or 600 pounds or so, before the rim even hits.

I would guess though that an outright breakage as opposed to bending probably is worsened a lot by fatigue.

The extra bearing is a great idea; in fact, Campagnolo freewheels were designed with one in there, but modern cassette hubs re-sited the rh bearing cup further outboard.

 

[gclark8]

A couple of observations here.

This is a spin-on freewheel, they come in 1, 5, 6, 7, 8 speed, getting progressively wider and with no support beyond the larger sprockets.

I can see merit in this idea for 6, 7, 8 speed freewheels, it may require experimeting with the best length spacer next to the cone to place the bearing in its optimum position.

One setback I can see, the need to remove the bearing from the axle in order to remove the freewheel with the splined special tool.

 

[RIPPERTON]

Actually gclark I realised this dissadvantage before I rang the bearing shop but I put it in the "so what" basket cause not breaking an axle was more important to me.

You actually just undo the right side cone and pull the axle out to change the freewheel. Something racers must do a lot but I never. I only use 5 of my 6 speeds on the way to work. Ive even removed the front derailleur and large chainring cause never use it

 

[RIPPERTON]

just thought of something. the geometry of the ball bearings going around the cone is completely screwed up if the axle bends or even flexes, which must cause friction and or pinching of the balls. I only rode the roady to work today for the first time and Im not sure if its my imagination or not but the back of the bike feels a lot more solid.

 

[gclark8]

....Get a 22mm OD, 10mmID sealed ball bearing and install it on the axle so it lines up with the outer edge of the cluster. The bearing will fit snugly (light push fit) into the special socket castlation used to remove the gear cluster (this is a Shimano Freewheel Hub) Juggle the spacers and lock nuts around so the bearing sits in the right position. (see photo)....

What is the Bearing Number you used?
What is the width of the bearing you used?
Would you consider upgrading your 6 to a 7 or 8 speed 11-24 and re-dishing the wheel?
Or, if it is a steel frame, increasing the rear drop out width to take the wider 7 or 8 speed freewheel?

 

[RIPPERTON]

What is the Bearing Number you used?
What is the width of the bearing you used?
Would you consider upgrading your 6 to a 7 or 8 speed 11-24 and re-dishing the wheel?
Or, if it is a steel frame, increasing the rear drop out width to take the wider 7 or 8 speed freewheel?

Dont know anything about the bearing except ID and OD width is about 6mm. Not going to spend any money on the bike. 6 speed is enough.

 

[celin721]

Get a pair of good wheels. If the axle breaks send it back to the company because of faulty products. An axle shouldn't break, thats just poor manufacturing or poor products.