4evrplan

I've got a cheap big-box store Schwinn mountain bike, a Ridge AL (circa '08 - ish) that I use as my main transportation on my short commute to and from work (and occasionally off-road). Today, I was mashing my way off the line at a stop sign on my way back to work from lunch and I hear a crunching noise after which the rear wheel is all loose and wobbly. The spokes are all still good, but there's something wrong with the interface between the axle and hub; that's where there's play. I haven't had time to take it apart and look at it, 'cause I had to get back to work, but I figure someone here would be able to tell me what happened from the description. Does anyone know what would cause this, and what needs to be replaced?

4evrplan

I got home at took it apart. The axle sheared in half:


So, my follow up question is "what should I replace it with?". I know little about axles/hubs/bearings, etc., but I know I want to replace it with something better than what came of[f] of it. What dimensions, brand, material, etc. should I look for, and are there any gotchas?

mrrabbit 

Before you replace, get the rear dropout alignment checked on the frame - especially if the dropouts are quality 5-7mm thick dropouts.

Should take an LBS only 5 minutes to do it for you. Then replace the axle and get back on the road.

=8-)

4evrplan

If they're not aligned, is it okay to bend them into alignment? It's an aluminum frame.

mrrabbit 

If it hasn't been done before and it's not too bad, no problem. Let the LBS be the judge.

=8-)

Spoonrobot 

Order a new axle from Harris or Loosescrews. You'll need to know some measurements.

https://sheldonbrown.com/harris/axles.html

https://www.loosescrews.com/index.cgi...d=862754121719

You'll also need some cone wrenches to disassemble and reassemble the hub properly.

The Ridge AL looks like it has a freewheel. Be prepared to replace the axle again. 7-speed freewheel set-ups are hard on axles.

dabac

As spoonrobot says, 7-speed freewheels are prone to this failure, that's why the majority of the industry stepped away from the freewheel design.
All axles are not designed equal, but I can't really advise on what to use. Don't use them/break them/work on them often enough to have developed a preference.
Here's a link: https://www.cyclingforums.com/t/442815/broken-rear-axle to someone who has another approach to the issue.

xenologer

If you want an upgrade, replace the entire hub and freewheel(the cogs) with a freehub style hub and cassete type gears.
Freewheel hubs (yours) are inherently weaker and prone to breaking axles compared to freehub style hubs, due to the design placement of the bearings.
Good article here shows the differences: https://sheldonbrown.com/k7.html
Note that this kind of upgrade requires relacing of the spokes, which is probably not cost effective compared to simply buying an entire freehub/cassete new wheel.

The inexpensive approach is to just replace the broken axel with a new one; no upgrade. and in the future be aware of the weakness of the design and ride accordingly; Never ride off a curb or other drop, get off the saddle and 'go light' on the pedals when crossing potholes/speedbumps/etc

4evrplan

The axle is 8mm diameter. If I replace all the nuts and cones, could I use a larger diameter axle, or are hubs specific to a matching axle size? And, if I can size up the axle, do I have to replace the cups as well? The spacers and washers have a bit of play, so hopefully, they wouldn't have to be replaced, and I suppose I could always drill them out a bit if they don't fit over a larger axle.

EDIT: I think I mis-measured. When I double-checked it looks closer to 9 - 9.5 mm, but it's hard to tell with the threads.

mrrabbit 

One last time...

1. Go to LBS and have the dropouts checked.
2. While there, get a replacement axle set - install.

=8-)

cny-bikeman

You cannot increase axle diameter. Get a chro-moly axle and adjust your riding habits, as it still takes a bit of abuse to break a solid axle even on a 7 speed freewheel.

bobotech

Are you a big rider? If so, go the freehub route. You can find 26" rear wheel freehub wheels all day long if you look around. I bought a trek bike recently just to part it out and it was from around 93 and had a 7 speed freehub wheel. Cost 20 dollars for the entire bike off of craigslist.

I replace all my freewheels with freehubs. I have converted three 27 1/4 inch freewheel rear wheels to freehub style just so I never have the problem of breaking or bending axles. I have done the same with a couple of older 700c freewheel wheels as well.

4evrplan

I know it's a good idea to support local business and all, but my LBS is truly horrendous, and I make it a point not to go there unless I have to. The only exception is if I'm in a big hurry and need a part that's not too expensive (like ball bearings) or if it's something I'm just not comfortable doing myself, like truing wheels (they actually seem pretty good at that, and it's only $20 per wheel).

I'll look for a good CrMo replacement and inexpensive cone wrenches.

dabac, I love the idea of adding that sealed bearing to spread the loads better, so I may do that as well. It might make little difference with loads from bumps, but for the low price, it can't hurt.

4evrplan

Ha! No. I'm really thin and about average to shortish height. Heaviest I've been is about 130 (out of shape with a desk job). Even so, converting to freehub's probably still a good idea. But, technically it's my wife's bike, even though I'm the only one that rides it, so I'm thinking about just getting it fixed back to stock quickly and looking for a CL bike for myself, even though there's pretty limited choices in my area.

dabac

I think you should measure again, I've never seen an 8 mm rear axle.

Well, the center cavity of the hub could probably take a thicker axle, but you'd have to real good/lucky to find another cone/ball combo that'll play nice with the existing cups.

For the cups, you're limited to the cutout in the hub, unless you fancy disassembling everything, sticking the hub in a lathe and rework it for a bigger cup.
They may well be hardened, and not take well to being drilled out.

4evrplan

You're right dabac, it's hard to tell with the shape of the threads, but I think it's in the 9/9.5mm neighborhood. I'll take it to a hardware store after work and see what size nut threads on.

dabac

Axles tend to use various versions of fine thread, far from certain that a regular hardware would carry things like that.

Shimano standard, I believe, is 10x1 mm thread.

cny-bikeman

To measure a threaded rod you need either a micrometer or calipers. With calipers you need to measure with the jaws at an angle to the threads so that they to not rest in the valleys at all. If you have neither best to borrow one.

Jeff Wills

Ditto. The vast majority of rear axles on current bikes are 10 x 1mm. Walk into any bike shop and they'll have a replacement.

OP: While you're at it, take the rest of the bike. The rear dropouts must be checked. This is a 1-minute job with common bike shop tools, nearly impossible without.

DannoXYZ 

If you measured around 9.5mm, then this is a 3/8" x 26tpi axle. Pretty common for lower-end hubs with solid axles. What you can do is upgrade to a 10mm chromoly axle. The extra 0.5mm of diameter actually makes a difference as stiffness goes up by the 4th power of diameter for 22% more strength.

Wheels Manufacturing makes a very good 10mm chromoly solid axle: AXLE-06. You'll need to measure the diameter of your existing hub-cones where it goes through the dust cap/seal and get new cones, washers and locknuts.

4evrplan

I got a replacement from the LBS. It turned out to be cheaper than ordering online, once you take shipping into account. I'm just waiting for cone wrenches to arrive in the mail. I'm pretty sure it's the same size as the old one, 'cause I think they checked it by screwing one of my old nuts on the new axle.

Jeff, I guess I'll take the bike in to have them check it (I hate taking the whole bike in 'cause they're kinda snobby). I just hope they don't try to charge me for that service, since I just bought the axle set from them. I do have an acquaintance who worked in a shop, has all his own tools and maintains a small private fleet of bikes. Maybe he'd check it for me.

Kimmo

Yep, good idea to trade up from the BSO.