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#1
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How to stop cranks loosening?
OK, this isn't quite as stupid a question as it seems...
When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens itself as a result of this. I retighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? Cheers Nick |
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#2
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How to stop cranks loosening?
NickD wrote: OK, this isn't quite as stupid a question as it seems... No stupid questiopns, just sometimes stupid answers. When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens itself as a result of this. I retighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? First time it loosened it was deformed and you may not ever keep it tight. Octalink and square taper to a lesser extent is prone to what you see when the crank is forced in the opposite direction of pedealing...you are a right foot forward guy, problem will be with the left/aft crank. New left crank arm, install correctly...at least the left is cheaper of the two. Cheers Nick |
#3
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How to stop cranks loosening?
Nick Drew writes:
OK, this isn't quite as stupid a question as it seems... When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens as a result of this. I re-tighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? http://www.sheldonbrown.com/brandt/l...ng-cranks.html There is no solution for "goofy footed" riding other than to relearn and lead with the left foot... or get different cranks. As you see, both Shimano and Campagnolo have addressed crank/spindle attachment with new designs that appear to get rid of that problem. Jobst Brandt |
#5
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How to stop cranks loosening?
Bill Sorenson writes:
OK, this isn't quite as stupid a question as it seems... When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens as a result of this. I re-tighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? http://www.sheldonbrown.com/brandt/l...ng-cranks.html There is no solution for "goofy footed" riding other than to relearn and lead with the left foot... or get different cranks. As you see, both Shimano and Campagnolo have addressed crank/spindle attachment with new designs that appear to get rid of that problem. Being strongly right-footed (and left-handed, BTW), I've led with my right foot since Day 1 on a bike, and have never once had a problem with the left crank coming loose. (All "older-style" BBs with various taper designs; no new "external bearings" types yet.) I think you missed the design feature that prevents this motion and retaining bolt loosening. If there is no press fit, there is backlash and it is this backlash that allows rotations large enough to unscrew the bolt. Square taper attachments do not suffer from this problem unless run with too little pressure in the taper fit. Granted, I tend to keep my butt planted on the saddle more than most, but I do unweight it over rough terrain and obstacles, of course. (Every once in a while I'll put the left foot forward just to try it, but it always feels awkward and I'm soon back to my natural position.) That has nothing to do with reverse torque on the spindle. Maybe I've just been lucky? Not from my perspective. Jobst Brandt |
#6
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How to stop cranks loosening?
On 16 Jun 2006 02:10:06 -0700, "NickD" wrote:
OK, this isn't quite as stupid a question as it seems... When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens itself as a result of this. I retighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? What you're doing is called being goofy-footed (no joke; the habit has a name), and it results in a reversal of the torque on the BB shaft, which is the easiest way to work a crank loose. On a square taper, it's been my experience that this isn't anywhere near as much of a problem as it is with Octalink...but in both cases, the crank gets damaged in the process, and each succeeding attempt at retightening has a shorter lead time to failure. Eventually, the hole will wallow out or (if it's a square taper) the crank may split from one of the corners. In any event, if the left crank has already been run loose, you're probably too late to save it, but you might as well keep running until it wallows past the point at which you can ignore the problem. If it was me, I would apply Loctite to the splines and bolt (if it's Octalink), or grease to the taper and Loctite to the bolt (if it's square taper), and shop for a replacement left crank. The most important thing, however, is to work on changing your standing habits. Until you stop putting the right foot forward, the problem will not go away without a different kind of crank set. If the standing habit isn't subject to change, you'll want to swap to a crank design that uses a pinch bolt for the left crank. There are several to choose from, but none are inexpensive yet. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts. |
#7
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How to stop cranks loosening?
wrote:
Bill Sorenson {who?} writes: {JB wrote:} There is no solution for "goofy footed" riding other than to relearn and lead with the left foot... or get different cranks. As you see, both Shimano and Campagnolo have addressed crank/spindle attachment with new designs that appear to get rid of that problem. Being strongly right-footed (and left-handed, BTW), I've led with my right foot since Day 1 on a bike, and have never once had a problem with the left crank coming loose. (All "older-style" BBs with various taper designs; no new "external bearings" types yet.) I think you missed the design feature that prevents this motion and retaining bolt loosening. If there is no press fit, there is backlash and it is this backlash that allows rotations large enough to unscrew the bolt. Square taper attachments do not suffer from this problem unless run with too little pressure in the taper fit. JFTR, most of my riding has been on Octalink or ISIS attachments. Only my first hardtail had (still has) square taper. Bill "and you misspelled my last name, " S. |
#8
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How to stop cranks loosening?
Thanks guys. Not much to add except: - I too have tried biking left foot forward, and it doesn't feel right, even on roads. On gnarly singletrack it's going to take a loooong time to relearn that... - I intend to go with square taper for my new hardtail - suggestion seems to be that this problem will be less of an issue with square taper - I'm aware I need to buy a new crank for my existing bike, and have found a place that does them. Just need to bite the bullet, really. Out of interest, if you ride LF forward, doesn't that mean the RH crank bolt backs off? Cheers Nick |
#9
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How to stop cranks loosening?
wrote in message
... Bill Sorenson writes: OK, this isn't quite as stupid a question as it seems... When I'm standing on the pedals (for a gnarly section, hopping over a kerb etc), I always have my right pedal forward, and the left at the back. Dunno why, but that's just the way it is. Problem is that my LH crank loosens as a result of this. I re-tighten it from time to time, but I'm aware that this isn't the best plan. So what's the best option? Loctite? Torque wrench (not sure about this, as the bolt can still back itself off)? Something else? http://www.sheldonbrown.com/brandt/l...ng-cranks.html There is no solution for "goofy footed" riding other than to relearn and lead with the left foot... or get different cranks. As you see, both Shimano and Campagnolo have addressed crank/spindle attachment with new designs that appear to get rid of that problem. Being strongly right-footed (and left-handed, BTW), I've led with my right foot since Day 1 on a bike, and have never once had a problem with the left crank coming loose. (All "older-style" BBs with various taper designs; no new "external bearings" types yet.) I think you missed the design feature that prevents this motion and retaining bolt loosening. If there is no press fit, there is backlash and it is this backlash that allows rotations large enough to unscrew the bolt. Square taper attachments do not suffer from this problem unless run with too little pressure in the taper fit. Granted, I tend to keep my butt planted on the saddle more than most, but I do unweight it over rough terrain and obstacles, of course. (Every once in a while I'll put the left foot forward just to try it, but it always feels awkward and I'm soon back to my natural position.) That has nothing to do with reverse torque on the spindle. Maybe I've just been lucky? Not from my perspective. Jobst Brandt Cool, thanks for the info. I have this same problem on my airport commuter bike. Since I cleaned and regreased the BB, which was dry at the time, I noticed this same problem myself. I think I'll try some locktite on the left crank bolt, as I have to use it for my business trip Monday. Anyway it has what appears to be a some kind of a early Shimano Octalink kind of a crank setup. But the BB has pressed in cups and simple caged bearings and isn't a more modern sealed bearing BB. So at the time I figured I couldn't just replace it with something else like the nice 46 tooth square tapered 3pc crankset I found at my local flea market bike shop. I guess I should have tried the crankset to see if it would have fit or not. But anyway, the left crank arm has that same getting loose problem too. But it looks like I might have to upgrade to a new Airport commuter bike later though. I think having it loosen up on me a few times might have gouged out the crank arm some so it maybe won't stay tight anymore. Sometimes I wonder if JB weld would work? My airport commuter bike is a junky old JC Penney 70's era touring bike that I converted over to a single speed and extended the rear rack to support a garment bag. I use this bike for when I need to go on a business trip and have to fly out and in from the Dallas Forth Worth International Airport here in Texas. I pedal on over to the airport and chain the bike inside the North Remote Parking lot. I figured if it looks like a crappy bike no one will mess with it. So far so good. Here are some pics of it http://s27.photobucket.com/albums/c1...ed%20RoadBike/ |
#10
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How to stop cranks loosening?
Earl Bollinger wrote:
My airport commuter bike is a junky old JC Penney 70's era touring bike that I converted over to a single speed and extended the rear rack to support a garment bag. I use this bike for when I need to go on a business trip and have to fly out and in from the Dallas Forth Worth International Airport here in Texas. I pedal on over to the airport and chain the bike inside the North Remote Parking lot. I figured if it looks like a crappy bike no one will mess with it. So far so good. Here are some pics of it http://s27.photobucket.com/albums/c1...ed%20RoadBike/ Nice rack! -- Dave dvt at psu dot edu One of the most time-consuming things is to have an enemy. -E.B. White, writer (1899-1985) |
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