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Dura-Ace crank problems?
My bike had developed a strange ticking noise which I finally traced to my
right crank/pedal interface. At 3 O'clock the pedal would get "set" and at around 11 it would click to "unset" itself--these were imperceptible movements of the pedal axle in the crank. So I removed the pedal, greased, and re-installed it. I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? The cranks on there are 7700 Dura-Ace, and the chainrings also seem to have a lot of blistering on the surface. Did Shimano change anything for 7701? Are Ultegra cranks any different, other than about $80 cheaper for 30 grams heavier? Cheers, Shawn PS: I have found one reference to speculation that Ultegra cranks may use a softer alloy with perhaps less precise teeth cut in the octalink, any experience with this? |
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#2
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Shawn Amir wrote in message ... My bike had developed a strange ticking noise which I finally traced to my right crank/pedal interface. At 3 O'clock the pedal would get "set" and at around 11 it would click to "unset" itself--these were imperceptible movements of the pedal axle in the crank. So I removed the pedal, greased, and re-installed it. I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? Install pedal with a pedal spanner. Oil is sufficient for assembly, grease will slowly migrate from area of high pressure leaving attachment not quite as tight as envisaged. Trevor |
#3
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Shawn Amir wrote in message ... My bike had developed a strange ticking noise which I finally traced to my right crank/pedal interface. At 3 O'clock the pedal would get "set" and at around 11 it would click to "unset" itself--these were imperceptible movements of the pedal axle in the crank. So I removed the pedal, greased, and re-installed it. I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? Install pedal with a pedal spanner. Oil is sufficient for assembly, grease will slowly migrate from area of high pressure leaving attachment not quite as tight as envisaged. Trevor |
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Shawn Amir wrote:
I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? They all get chewed up like that (TA recommend the use of a washer between the pedal and their cranks). The only broken cranks that I've seen both went at the pedal end. |
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Shawn Amir wrote:
I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? They all get chewed up like that (TA recommend the use of a washer between the pedal and their cranks). The only broken cranks that I've seen both went at the pedal end. |
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Zog The Undeniable wrote in message 4132d56d.0@entanet... Shawn Amir wrote: I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? They all get chewed up like that (TA recommend the use of a washer between the pedal and their cranks). The only broken cranks that I've seen both went at the pedal end. Quality pedals have the thread taper out,leaving a gap between pedal axle boss and thread so removing the stress raiser which would otherwise exist at the face of the crank at the pedal eye. A taper on the pedal eye will reduce the stress raiser. I wonder when and why TA recommended this practice of fitting washers, it should have no significance with normal materials. I think it would have a detrimental effect, because it would be taking the axle thread to the face of the crank so negating the advantageous thread form of the axle. Trevor |
#7
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Zog The Undeniable wrote in message 4132d56d.0@entanet... Shawn Amir wrote: I also noticed a lot of fretting at the face of the crank arm where it attaches to the pedal. The last 1/3 of the pedal threads had a lot of fine metallic powder on them. I suspect that I must have neglected to grease the pedal when I first installed it.... but all this fretting in only 5000 miles seems a wee bit scary. I weight less than 195 these days and no one would call me a strong rider... so what gives? They all get chewed up like that (TA recommend the use of a washer between the pedal and their cranks). The only broken cranks that I've seen both went at the pedal end. Quality pedals have the thread taper out,leaving a gap between pedal axle boss and thread so removing the stress raiser which would otherwise exist at the face of the crank at the pedal eye. A taper on the pedal eye will reduce the stress raiser. I wonder when and why TA recommended this practice of fitting washers, it should have no significance with normal materials. I think it would have a detrimental effect, because it would be taking the axle thread to the face of the crank so negating the advantageous thread form of the axle. Trevor |
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