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Post by dracco on Oct 21, 2021 19:10:41 GMT
Here's a report of an incident that happened to me today. Being a sunny (but cold) day I took my Pro out for a ride in the lanes south of Harrogate. There's a really nice circuit that I often take that goes through the villages on the south side of Wharfedale, incorporates some punchy climbs and some exhilarating descents.
As I was descending fast, on the big chainring, down to Wetherby on the Linton Road, I went up over a bridge that to overflies a disused railway line (easing back 2 sprockets to maintain my cadence) and on cresting it, shifted my rear derailleur back into the smallest sprocket whereupon there was a sudden clatter and I saw my chain falling off the outside of my FRONT chainring (alarming!). The next thing I knew was that my rear wheel had locked solid and was skidding out to the left, whereupon I ended up sliding along the road on my back.
The good news is that I incurred no serious injury (actually, not even a minor injury). I was well wrapped up against the cold wind, and my jacket acted like motorbike leathers. My helmet did suffer a resounding impact, but it did its job and protected my noddle. (A new one is now first on my shopping list - the same model if I can find one, since I know now that it works!). I dread to think what would have happened if I hadn't been wearing one. Two cyclists who were on on the other side of the road saw this happen and immediately stopped to offer assistance. I was OK, and both asked me what had happened, because (as one said) one moment I was riding in complete control ("looking pretty good"), and the next I was sliding along the road. My first thought was that some catastrophe had resulted in my rear derailleur jamming into the spokes, but in fact my chain had completely come off the RD, which looked to be undamaged. (I've seen what happens when a Suntour Cyclone long-cage RD makes inappropriate contact with spokes, and it's not pretty).
But, the upshot of this that my rear wheel is completely trashed. It was irretrievably buckled and jammed in between the rear triangle stays. The good news is that the frame remains undamaged: that Aerospace tubing is really resilient. After my wife recovered me from the roadside (I wasn't going to be riding any further) and took me home I checked over the bike more carefully, and reckoned that at least the hub (Miche) and freewheel (IRD Classica) were OK, so that I should be able to transfer them to a new rim. (If anyone out there has a Mavic MA2 36-hole rim, I'll be happy to take it off their hands....)
This is when I discovered that - while the hub and freewheel appeared to be OK, the hub's through axle had sheared cleanly right at the point where it met the driveside cone set (essentially, when I pulled out the QR skewer, a length of axle came away with it).
So, the questions I'd like our resident mechanics to answer are thess: Do you think that it was a failure of the axle that directly caused my crash? With the break occurring right at the point of the driveside cone I can envisage that the power being transmitted through the chain would then distort the angle of the freewheel (although the QR skewer isn't bent) sufficient to bring the rim and tyre into sudden contact with the seat- and chain-stays and the consequent buckling of the wheel as a result of the unexpected intimacy between light alloy and Phoenix 1027 steel (only one likely winner, there). Does this sound like a reasonable scenario?? There was otherwise certainly nothing untoward in my gear change, and this was on a stretch of road that I've ridden over at similar speeds time and again (it's a great short 2-hour training circuit).
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Post by brianbutler on Oct 21, 2021 20:43:27 GMT
I have had one experience with a sheared rear axle and it was nothing like yours. I didn't even know it was broken until I went to repack the wheel bearings and, as in your case, part of the axle came away with the QR skewer. When I posted this, I think Wheelson mentioned that he has seen this many times in his bike shop but I will let him speak for himself. Based on that, it may be that the broken axle was an effect and not a cause of the malfunction and crash, which could have been a broken spoke and wheel collapse.
I'm sorry to hear about the crash and glad it was the rear wheel instead of the front.
Brian
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Post by wheelson on Oct 21, 2021 21:21:01 GMT
I have had one experience with a sheared rear axle and it was nothing like yours. I didn't even know it was broken until I went to repack the wheel bearings and, as in your case, part of the axle came away with the QR skewer. When I posted this, I think Wheelson mentioned that he has seen this many times in his bike shop but I will let him speak for himself. Based on that, it may be that the broken axle was an effect and not a cause of the malfunction and crash, which could have been a broken spoke and wheel collapse. I'm sorry to hear about the crash and glad it was the rear wheel instead of the front. Brian Brian, you’re right in that I’ve seen more than a few broken axles, totally undetected and held together by the quick release skewer. Not so with bolt-on axles. I would tend to agree that the wheel taco was caused by something else. Unless the culprit is visible, such as broken spokes or a broken hub flange, I would expect low spoke tension, with an unloading causing the disaster. Best, John “wheelson” |
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Post by brianbutler on Oct 21, 2021 22:19:56 GMT
I have had one experience with a sheared rear axle and it was nothing like yours. I didn't even know it was broken until I went to repack the wheel bearings and, as in your case, part of the axle came away with the QR skewer. When I posted this, I think Wheelson mentioned that he has seen this many times in his bike shop but I will let him speak for himself. Based on that, it may be that the broken axle was an effect and not a cause of the malfunction and crash, which could have been a broken spoke and wheel collapse. I'm sorry to hear about the crash and glad it was the rear wheel instead of the front. Brian Brian, you’re right in that I’ve seen more than a few broken axles, totally undetected and held together by the quick release skewer. Not so with bolt-on axles. I would tend to agree that the wheel taco was caused by something else. Unless the culprit is visible, such as broken spokes or a broken hub flange, I would expect low spoke tension, with an unloading causing the disaster. Best, John “wheelson” Wheel taco! I love it. Brian
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Post by wheelson on Oct 21, 2021 22:52:12 GMT
Brian, you’re right in that I’ve seen more than a few broken axles, totally undetected and held together by the quick release skewer. Not so with bolt-on axles. I would tend to agree that the wheel taco was caused by something else. Unless the culprit is visible, such as broken spokes or a broken hub flange, I would expect low spoke tension, with an unloading causing the disaster. Best, John “wheelson” Wheel taco! I love it. Brian
I can’t claim credit for that one but a good description, I guess. I’ll relate an experience I had with a somewhat similar problem as dracco’s, only no rider displacement involved. A few years ago I was riding my Schwinn Voyageur SP, 27 inch wheels, good quality Wolber / Super Champion rims, wheels built by yours truly and used for several years. Due to a derailleur maladjustment, I over shifted into the spokes, breaking several and jamming things up. With a bit of tweaking including prying out the chain and maladjusting some spokes, I was able to ride home. Some days later, I decided to replace all the drive side spokes. As I was de-tensioning the spokes, the rim suddenly went ballistic and went into a permanent “taco” state. No amount of work would correct this, and I assume that somehow the tweaking I did and then riding home introduced some major league stress that took off like a rocket at de-tensioning. Perhaps this is what happened to dracco’s wheel, only in a near instantaneous manner. Best, John “wheelson” |
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Post by oldroadietehachapi on Oct 22, 2021 3:54:55 GMT
I have had one experience with a sheared rear axle and it was nothing like yours. I didn't even know it was broken until I went to repack the wheel bearings and, as in your case, part of the axle came away with the QR skewer. When I posted this, I think Wheelson mentioned that he has seen this many times in his bike shop but I will let him speak for himself. Based on that, it may be that the broken axle was an effect and not a cause of the malfunction and crash, which could have been a broken spoke and wheel collapse. I'm sorry to hear about the crash and glad it was the rear wheel instead of the front. Brian Scary crash! Like Brian, I have only had one broken axle. Again, like Brian, I did not know it was broken and rode it like that for a good long while. I only discovered the problem when I tried to adjust the bearing free play. I once had a brand new wheel do the taco thing. It was on my first ride on the brand new, very inexpensive, Vilano (made in China) bike, which I had bought to loan out on group rides. I rode it about 100 feet and made an easy U turn. The wheel simply started rubbing on both chain stays. Had I been going faster I might have had a spectacular crash. I was able to adjust the spoke tension and true both wheels. As for the broken axle causing your crash; I have no idea! I am very glad to hear that you were not injured. If you buy a replacement wheelset, please be certain that it has a reputable pedigree.
Ride Safe Jim
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Post by brianbutler on Oct 22, 2021 12:39:22 GMT
Jim, good point about the quality of the wheel set. I think the components (rims, spokes, hubs, axles, bearings) are pretty good even on cheap wheels but robotic tensioning and lack of followup by a human being can lead to a very weird wheel. I bought an inexpensive wheel set and decided to adjust the spokes since it was slightly out of true. I was astounded at how much difference there was between adjacent spokes. There are a nearly infinite number of spoke/tension combinations that will true a wheel but if I build one (or true up a new or old one) I try to get the spokes as evenly tensioned as possible and close to the specified tension. I use a spoke tension gauge early in the process and until the wheel is close to correct. It might be possible to develop the skill to judge tension without it but I don't do it frequently enough to trust myself.
Brian
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Post by wheelson on Oct 22, 2021 15:58:30 GMT
Jim, good point about the quality of the wheel set. I think the components (rims, spokes, hubs, axles, bearings) are pretty good even on cheap wheels but robotic tensioning and lack of followup by a human being can lead to a very weird wheel. I bought an inexpensive wheel set and decided to adjust the spokes since it was slightly out of true. I was astounded at how much difference there was between adjacent spokes. There are a nearly infinite number of spoke/tension combinations that will true a wheel but if I build one (or true up a new or old one) I try to get the spokes as evenly tensioned as possible and close to the specified tension. I use a spoke tension gauge early in the process and until the wheel is close to correct. It might be possible to develop the skill to judge tension without it but I don't do it frequently enough to trust myself. Brian Excellent observations. I agree wholeheartedly about machine built wheels not always being true or properly tensioned. I’ve seen false tension on some spokes based on an improperly thread start of the nipple. At the shop, I never use or sell a new wheel (or a new bike for that matter) without at least a quick tension and true. I seriously doubt a spoke thread lube/lock is ever used on cheaper wheels, which would contribute greatly to tension variability. Remember, vintage rims run at a much lower spike tension and may need spoke nipple washers depending on rim specs. Again, a good spoke thread lube/lock is always a good idea. Old-timers used linseed oil (caution: linseed oil soaked rags can auto-ignite!). I personally use a mild thread locker (Loctite purple) or sometimes “after lock” (Loctite green). The latter is especially good for e-bike wheels, notorious for spoke loosening. Best, John “wheelson” |
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Post by brianbutler on Oct 22, 2021 18:51:29 GMT
So, John, are you saying Loctite purple works first as a lube while truing and then sets to hold the threads? If so, that sounds like something I will start doing. How long is the working time before it sets? I'm a slow wheel builder. I currently only do the lubrication step, and not with anything special - just a dab of grease or drop of oil. I have not had any spokes loosen up but maybe I'm tempting fate.
Brian
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Post by wheelson on Oct 22, 2021 21:02:51 GMT
So, John, are you saying Loctite purple works first as a lube while truing and then sets to hold the threads? If so, that sounds like something I will start doing. How long is the working time before it sets? I'm a slow wheel builder. I currently only do the lubrication step, and not with anything special - just a dab of grease or drop of oil. I have not had any spokes loosen up but maybe I'm tempting fate. Brian It seems as my building technique is evolving. For many years I used nothing at all. For the last 8 to 10 years, as I’ve been dealing with modern rims and higher tensions, a lube of some sort is almost a necessity. That said, my building method hasn’t changed much over the years, a modified Schwinn school method: load all the spokes in the hub, hub and rim flat on a table (hole in center of table is great as in old deck table with umbrella hole!), loosely build one side of the wheel, flip it over and build the other side. Now I generally put the wheel in the truing stand. Since the wheel is loosely built and spoke threads are showing, I put a tiny drop of purple Loctite on each spike as I go around the wheel. If I’ve calculated the spoke length correctly, I should be able to go to inside end of nipple to just hide the spoke thread, then go from there. The purple stuff is pretty slow and mild, just sort of making the nipple turning “sluggish”. If the wheel is already built with too loose tension but the nipples freely turn, I usually just tension and true and then put a small drop of green “after lock” Loctite down each spoke nipple head hole when I’m finished t&t. It’s very fluid an easily penetrates. Since it quickly disappears down the threads it’s also very easy to use way too much and make a mess. Probably way more than you wanted to know but this is what works for me, no guarantees for anyone else! Best, John “wheelson” |
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Post by brianbutler on Oct 23, 2021 17:34:04 GMT
So, John, are you saying Loctite purple works first as a lube while truing and then sets to hold the threads? If so, that sounds like something I will start doing. How long is the working time before it sets? I'm a slow wheel builder. I currently only do the lubrication step, and not with anything special - just a dab of grease or drop of oil. I have not had any spokes loosen up but maybe I'm tempting fate. Brian It seems as my building technique is evolving. For many years I used nothing at all. For the last 8 to 10 years, as I’ve been dealing with modern rims and higher tensions, a lube of some sort is almost a necessity. That said, my building method hasn’t changed much over the years, a modified Schwinn school method: load all the spokes in the hub, hub and rim flat on a table (hole in center of table is great as in old deck table with umbrella hole!), loosely build one side of the wheel, flip it over and build the other side. Now I generally put the wheel in the truing stand. Since the wheel is loosely built and spoke threads are showing, I put a tiny drop of purple Loctite on each spike as I go around the wheel. If I’ve calculated the spoke length correctly, I should be able to go to inside end of nipple to just hide the spoke thread, then go from there. The purple stuff is pretty slow and mild, just sort of making the nipple turning “sluggish”. If the wheel is already built with too loose tension but the nipples freely turn, I usually just tension and true and then put a small drop of green “after lock” Loctite down each spoke nipple head hole when I’m finished t&t. It’s very fluid an easily penetrates. Since it quickly disappears down the threads it’s also very easy to use way too much and make a mess. Probably way more than you wanted to know but this is what works for me, no guarantees for anyone else! Best, John “wheelson” Thanks for the write-up. I'm not too far from that technique, except I do both sets of "inside" spokes first, then the outsides. Otherwise I can't get the second set of insides through the finished side. I'll try some purple Loctite next time.
Brian
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Post by dracco on Oct 23, 2021 20:00:19 GMT
Looks like I've started an interesting debate. I'm pretty certain that I didn't direct the RD into the spokes: I was shifting away from the spokes (outward). Additionally, although clearly being "of a certain age", the wheel and spokes (Mavic MA2 and DT-Swiss) were good quality, true and with good spoke tension. Even after the crash, none of the spokes are broken - but quite a few are now badly bent. "Taco" certainly describes the current state of the wheel!
(I've had prevous experience of shifting an RD into the spokes on another bike, some several years ago - an event that trashed the RD, but left the spokes pretty much intact. I was able to get home in that instance by taking off the RD and shortening the chain so that I could ride it as a single-speed (actually, since I could still use the FD, it was a 2-speed)).
I'm now trying to get the freewheel off the hub. So far it's resisted all my efforts using a spanner (US "wrench"), and a spanner and a chainwhip. I think that the most effective way will be to hold the removal tool in a vice (US "vise"), but unfortunately the only vice I have is rather small and only fixes to a workbench by a clamp, rather than being bolted in situ, and so isn't immovable - so far I haven't been able to exert the necessary force on the rim without turning the vice along with everything else. It looks like I'll have to see if my LBS can liberate it.
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bendo
Viscount
Posts: 538 
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Post by bendo on Oct 24, 2021 11:13:11 GMT
Glad you're OK Dracco and glad you were wearing a helmet. You certainly wouldn't be typing up this interesting report on the same day! When you said "Death..." I assumed you meant Viscount, lol! It took me a while to realise it wasn't a Viscount hub. Small relief there as we know that Viscount's parts metallurgy was sometimes a bit variable. I don't have anything learned to add other than the observation that wheel failures of all kinds nearly always happen on the rear because it carries the weight of the rider. Not casting nasturtiums at your weight Dracco! It's a general observation. Perhaps there is some information on the net for that generation of Miche hubs?
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Post by dracco on Oct 24, 2021 14:29:54 GMT
Hi Bendo. Only 60kg mate!
I first started wearing a helmet when I was working in Australia for 6 months, and helmet wearing was compulsory. A good habit to continue with.
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bendo
Viscount
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Post by bendo on Oct 25, 2021 0:25:05 GMT
Wow, you're even lighter than me!
I was going to add to your comment about helmets, but thought better of it, lest it derail the thread! Suffice to say that I too have had the pleasure of binning a crashed helmet that did its job.
b
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Post by franco on Oct 25, 2021 22:53:39 GMT
Glad you are okay Dracco.
The worst I have experienced in recent years is a rear derailleur going into the spokes from a failing retaining bolt, it took three spokes out and the rear wheel was a mess.
It crosses my mind many times what could happen, new or old bike, there are failing parts no matter how good we are at bicycle maintenance as individuals.
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bendo
Viscount
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Post by bendo on Oct 26, 2021 10:59:44 GMT
Glad you are okay Dracco. The worst I have experienced in recent years is a rear derailleur going into the spokes from a failing retaining bolt, it took three spokes out and the rear wheel was a mess. It crosses my mind many times what could happen, new or old bike, there are failing parts no matter how good we are at bicycle maintenance as individuals. That's a good point. I often think about this when I adjust my centrepull brakes: if the 7mm dome nut that holds the brake cable in the straddle cable yoke fails or is not quite tight enough... no brakes. There are lots of individual parts like that when you think about it. And I'm sure everyone here does, it's just something that hits home sometimes: how much trust we put in our machines. b |
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Post by wheelson on Oct 26, 2021 14:31:58 GMT
Glad you are okay Dracco. The worst I have experienced in recent years is a rear derailleur going into the spokes from a failing retaining bolt, it took three spokes out and the rear wheel was a mess. It crosses my mind many times what could happen, new or old bike, there are failing parts no matter how good we are at bicycle maintenance as individuals. That's a good point. I often think about this when I adjust my centrepull brakes: if the 7mm dome nut that holds the brake cable in the straddle cable yoke fails or is not quite tight enough... no brakes. There are lots of individual parts like that when you think about it. And I'm sure everyone here does, it's just something that hits home sometimes: how much trust we put in our machines. b All of this is so very true. There are so many points of failure on bikes, some critical some not. The key is to be proactive with bike maintenance with a “what if” attitude. Its incredible to see 40 - 50 year old bikes come into the shop that haven’t seen a wrench since day one. In addition, the road and weather conditions can also bite, that totally out of place bit of gravel on the road or broken bottle or pothole or missing bridge planking. I’ve been a victim of all the above. I’ve been a helmet believer since that first Bell Biker and owe my life to helmets at least twice - enough to make a believer out of Mrs.W and to thankfully translate to my daughter, son, and grandson. Just like bike maintenance and that last minute pre-ride inspection, it’s never wrong to control the things you can, to others we just have to hope and pray for the best. Best, John “wheelson” |
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