Broken Rear Axle - How?

McBain_v1

On my winter bike and I noticed that when climbing steep hills, getting out of the saddle to try and "power" up them, the rear wheel would pull over to one side and jam against the frame, thereby arresting all forward motion. This was damned irksome and I put it down to the QR not being tight enough.

I've since discovered that the rear axle in the wheel was broken into an impressive number of shards.

How does this happen :?: Is there anything that can be done to prevent a re-occurence or is it just metal fatigue :?:

nicklouse

some axles are more pron to breakage than others.

what hub? and spin on block or a cassette?

will3

Yes probably fatigue. All the ones I've broken have been. Shimano freehubs help here as the bearings are more evenly spaced - but remember Shimano have a patent on this so other co's freehubs will likely have the drive side bearing inboard of the freehub.

McBain_v1

Metal fatigue seems to be the most obvious - just glad it wasn't something I've done. Anyway, new axle fitted by experienced grease-monkey at LBS so hopefully this weekend will not be as entertaining 8)

Rob Sallnow

will3 wrote:

Yes probably fatigue. All the ones I've broken have been. Shimano freehubs help here as the bearings are more evenly spaced - but remember Shimano have a patent on this so other co's freehubs will likely have the drive side bearing inboard of the freehub.

I seem to recall Shimano changed the arrangement of the bearings for their current Dura Ace hubs to be positioned just like Campag's. So it can't be that inferior a design.

geoff_ss

It happens. On long tours where spares might be difficult to find it's worth carrying a spare rear axle. Fortunately with a quick release wheel the bike's still ridable and you often don't find out until you remove the wheel.

We broke the Maxicar braked hub on the back of the tandem and the bike was totally useless. George Longstaff came by a few minutes later and told us he had spare axles in stock (what a fine gent he was). Absolute swine to repair as I recall.

Geoff

McBain_v1

Looking at it, the axle seems to have sheared into two bits, and then been ground up some more into more bits. It's just not a bit I ever expected to "go wrong".

will3

Rob Sallnow wrote:

will3 wrote:

Yes probably fatigue. All the ones I've broken have been. Shimano freehubs help here as the bearings are more evenly spaced - but remember Shimano have a patent on this so other co's freehubs will likely have the drive side bearing inboard of the freehub.

I seem to recall Shimano changed the arrangement of the bearings for their current Dura Ace hubs to be positioned just like Campag's. So it can't be that inferior a design.

Properly designed there's nowt wrong with either design but my engineer's spider senses tell me that the Shimano design is the more logical one.
Is Dura Ace designed with performance or durability as the most important factor?
It's also fair to say that Dura Ace was never designed for touring ie with the wheel load an issue.

nicklouse

The current Dura Ace still has the bearings at the ends of the axle as before, But the diameter of the main axle has increased to 14mm.

will3

Well there you go. The reason that the shimano system is better is that it does not impart as much bending load on the axle. In the days of freewheels bent axles were not uncommon, esp for heavy riders like me.

Rob Sallnow

nicklouse wrote:

The current Dura Ace still has the bearings at the ends of the axle as before, But the diameter of the main axle has increased to 14mm.

Looking at the technical PDFs on the Shimano site the 7800 and 7801 rear hub has the same drive side hub bearing arrangement as Campag has had for years.....ie just over a 1/3 of the way in to the length of an oversized axle with a bearing surface as part of that axle. The 7700 hub, however old that is, runs an axle that looks just like an old freewheel hub of yesteryear, thin, threaded both sides for most of it's length which I presume allows the driveside bearings to be placed outside of the hubshell and nearer the dropout. If Campag had run that thin an axle and have the bearings in the hubshell I could understand people claiming Shimano hubs are 'stronger' but Campag have been running oversized axles since 1999 and before that were slightly thicker than a 7700 axle.

nicklouse

Rob Sallnow wrote:

nicklouse wrote:

The current Dura Ace still has the bearings at the ends of the axle as before, But the diameter of the main axle has increased to 14mm.

Looking at the technical PDFs on the Shimano site the 7800 and 7801 rear hub has the same drive side hub bearing arrangement as Campag has had for years....

agreed.

have a look at the Current 7850

Rob Sallnow

nicklouse wrote:

Rob Sallnow wrote:

nicklouse wrote:

The current Dura Ace still has the bearings at the ends of the axle as before, But the diameter of the main axle has increased to 14mm.

Looking at the technical PDFs on the Shimano site the 7800 and 7801 rear hub has the same drive side hub bearing arrangement as Campag has had for years....

agreed.

have a look at the Current 7850

Ok, didn't spot that as it wasn't labeled like the others and I've no idea what model is the current one....maybe the 7800 hub was a breach of someone's patent!! Looks to me like the 7850 axle is thinner than the 7800 judging by the threads of the bolts used (15v14) 13 bearings it has rather than the 14 of the older design.

Nigel Bennett

I lost count of the number of Campag axles I broke, in the "good old days" of the Large Flange hubs and screw-on 5-speed blocks. I've only bust one Shimano axle (and that was a front) in the last 20 years since changing to the Freehub system.

I dare say I'd have had the same improved experiences if I'd stayed with Campag, but it just happened that I standardised on Shimano.

Rob Sallnow

Nigel Bennett wrote:

I lost count of the number of Campag axles I broke, in the "good old days" of the Large Flange hubs and screw-on 5-speed blocks.

Same here...not just Campag, Maillard and others plus whatever axles I bought as spares and replacements.

Never broken a freehub style axle though

geoff_ss

Rob Sallnow wrote:

Nigel Bennett wrote:

I lost count of the number of Campag axles I broke, in the "good old days" of the Large Flange hubs and screw-on 5-speed blocks.

Same here...not just Campag, Maillard and others plus whatever axles I bought as spares and replacements.

Never broken a freehub style axle though

Well that's certainly my experience too but the vast majority of my 'serious' cycling was done before I moved to freehubs. The bearings were always a long way from the axle support at the drop out - a recipe for trouble but it mostly worked OK and it was nice to be able to build a frewheel with your own sprocket choice.

Geoff

Rob Sallnow

Geoff_SS wrote:

Rob Sallnow wrote:

Nigel Bennett wrote:

I lost count of the number of Campag axles I broke, in the "good old days" of the Large Flange hubs and screw-on 5-speed blocks.

Same here...not just Campag, Maillard and others plus whatever axles I bought as spares and replacements.

Never broken a freehub style axle though

Well that's certainly my experience too but the vast majority of my 'serious' cycling was done before I moved to freehubs. The bearings were always a long way from the axle support at the drop out - a recipe for trouble but it mostly worked OK and it was nice to be able to build a frewheel with your own sprocket choice.

Geoff

You couldn't beat the days of the early Campag freehub and the Mk 1EXA Drive sprockets...everything from 12 to 32 teeth except 27,29 and 31 allowing you to put together whatever ratios took your fancy though they did have a chart telling you how to line the things up...but such was the subtle effect of the cog's scalloping it didn't really make any difference to shifting, not like the next generation with proper ramping.