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#21
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Advice regarding Octalink BB/Crank
On Jun 9, 5:53*am, somebody wrote:
On Mon, 8 Jun 2009 14:17:26 -0700 (PDT), Jay Beattie wrote: If I were looking for something used, I would go with square drive. Isis and Octalink BBs have the whole bearing failure issue (ISIS more than Octalink), so even if you mount the cranks right, the BB has got a severely limited life expectancy. I never had a problem with square drive, notwithstanding the claims about spindle breakage, etc. Bearings would wear out, but only after a good long time. -- Jay Beattie. What bearing failure issues do ISIS have, and why does the BB have a limited life? *I have a couple ISIS and want to know what to look for. I believe that because the axle spindle is a larger diameter the space between the BB shell and the axle is less, meaning only smaller ball bearings can be used- |
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#22
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Advice regarding Octalink BB/Crank
On Jun 8, 8:43*pm, wrote:
Jay Beattie wrote: I have owned one Octalink setup. *I consistently had problems with the crank bolts loosening, and the cranks loosening on the splines. *Very frustrating. I'm now looking for a compact crank, and the majority of the offerings on the Bay are Octalink. *Can I learn to install an Octalink set-up satisfactorily? *What's the trick? Problem with Octalink and Isis is that if you didn't install them properly the first time and you damaged the teeth or groves you are screwed. *You need to make sure that you install them and the fit is exact. *Either square taper or the new external BB's are a lot more tolerant of mistakes. *If you have a choice go for either one. *You'll find a lot of Octalink and ISIS on sale because they are getting phased out. *I have had ISIS and it has worked fine. *But I am always very careful making sure to get proper fit. *However I'd rather use square taper. I have a brand new campy chorus triple square taper that I bought for $30 on ebay. *If the Isis fails, I'll toss it and install the campy. *You should be able to find some compact square taper cheap if you look around. Not so. *All Octalink transmitting high torque loosen their retaining bolt, new or used, and installed by experts and amateurs alike. *What do you perceive is the opposite from "install them properly the first time"? *How does one "damaged the teeth or groves" on installation? How are you "always very careful making sure to get proper fit". *How does one not get a "proper fit?" Because with the Octalink BB (at least the original design) you could get the feeling of proper engagement and actually be slightly off. *You had to look carefully to make sure the splines were properly engaged. *This is not myth or lore -- lots of people made this mistake, including me (working in a hurry). *It results in early crank death. This is a digital system. *How can one be "slightly off". *Either the spline is engaged or not. *You are still hedging on what goes wrong. You didn't exactly say so, but it sounds like some installations are made without engaging the spline and trying to tighten it into place, tooth on tooth. *Why don't you come right out and say so. *That way people who have these cranks would be able to use the information. *The word "properly" is suitably mysterious for someone not skilled in mechanical assembly. Properly means that by feel, it seems to fit like a puzzle piece, but in fact, there is a misfit. I have not had any problem with loosening with an Octalink absent a problem with the initial installation. This is an amazing dodge and weave diversion from what is happening. Are you saying users put cranks on randomly and hoped that with enough tightening the spline would find its way? *This sounds absurd! One more time with emphasis: you can misinstall Octalink cranks and permanently ruin the interface. I have a day job (which isn't being an engineer) and do not have time to pull my cranks apart or get the old ruined one out of a box and do CSI basement bike shop, so I will leave that to others with more time and talent. I could make a guess at what happens, but that would just be more dodging, weaving, diversion, myth, lore, absurdity, baloney, hedging, etc., etc. -- Jay Beattie. |
#24
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Advice regarding Octalink BB/Crank
On Jun 8, 9:43*pm, wrote:
Jay Beattie wrote: This is an amazing dodge and weave diversion from what is happening. Are you saying users put cranks on randomly and hoped that with enough tightening the spline would find its way? *This sounds absurd! Count me as another data point in the "ocatalink crank can be installed incorrectly" camp. My experience is limited, but is actual rather than hypothetical. DR |
#25
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Advice regarding Octalink BB/Crank
On Jun 9, 9:42 am, DirtRoadie wrote:
On Jun 8, 9:43 pm, wrote: Jay Beattie wrote: This is an amazing dodge and weave diversion from what is happening. Are you saying users put cranks on randomly and hoped that with enough tightening the spline would find its way? This sounds absurd! Count me as another data point in the "ocatalink crank can be installed incorrectly" camp. My experience is limited, but is actual rather than hypothetical. DR And "actual" experience is what counts, not the hypothetical bloviations of an internet gasbag. |
#26
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Advice regarding Octalink BB/Crank
Chalo wrote:
The gold standard of reliability and ease of service is the one-piece crank. if all you've got is a hammer Square taper BBs are several steps more finicky, demanding, and unreliable. ISIS BBs are even worse, and Octalink is, as far as I know, the worst system that ever got significant market penetration-- both in reliability and in ease of service. Octalink BB's are much better than the usual ISIS crap with tiny industrial bearings. Splined 2-piece cranks conforming to Roger Durham's patent are worlds better than anything road bikes and MTBs have used in threaded shells in living memory. if you call bearing replacement together with the new chain an improvement. They can also be pretty hard on the threads in the BB shell I'm sure Shimano has figured out some way to fawk them up, but they are a fundamentally sound design (unlike Octalink). Apart from the basic error that the pressfits are the wrong way round you mean? -- /Marten info(apestaartje)m-gineering(punt)nl |
#27
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Advice regarding Octalink BB/Crank
On Jun 9, 10:18 am, wrote:
ozark bicycles wrote: I'm now looking for a compact crank, and the majority of the offerings on the Bay are Octalink. Can I learn to install an Octalink set-up satisfactorily? What's the trick? Use a torque wrench. A strain guage should be fairly inexpensive make certain everything is very clean, I put some lithium grease on the splines to eliminate creaking; I install the adjusting crank onto the axle to the max torque spec and feel to make sure there is no play. I think Loctite is recommended, but I don't like to use that because if there is any play it makes adjustment difficult and leaves a residue on the threads. Then the crank fixing screws get one turn each in alternating pattern untill I reach more than half-way of the torque spec.range. And then there is the way that people _actually_ service their bikes. Although I don't think you were talking about what is usually called a "strain gauge", a strain gauge is a great example of what should never, ever be required for the safe and reliable operation or maintenance of a bicycle: http://tinyurl.com/kustmy The gold standard of reliability and ease of service is the one-piece crank. Square taper BBs are several steps more finicky, demanding, and unreliable. ISIS BBs are even worse, and Octalink is, as far as I know, the worst system that ever got significant market penetration-- both in reliability and in ease of service. Splined 2-piece cranks conforming to Roger Durham's patent are worlds better than anything road bikes and MTBs have used in threaded shells in living memory. I'm sure Shimano has figured out some way to fawk them up, but they are a fundamentally sound design (unlike Octalink). I have encountered some lossening after a number of rides in varying environmental conditions (very slight, minimal play), but I reinstall cranks as described so I have not observed any damage to the cranks or bb spindle; doubtless, if I leave things they would get damaged. So after your laboratory-grade installation procedure, Octalink cranks still loosen in normal use. That's a perfect illustration of the problem with them, and why they should never have been foisted on an unsuspecting consumer market. I'm not a big fan of Octalink, but the problems I have seen have been around somewhat short bearing life and fussy initial installation. What is different between "Initial installation" and subsequent installation? Shall I assume that your newsreader only allows you to reply to certain posts? Why else would you reply to this post, made in reply to Chalo Colina, whilst seemingly ignoring my earlier post directed to you? the fault must lie in the newsreader, surely you wouldn't be avoiding a question now, would you Jobst? So, once again: have you ever installed an Octalink crank on an Octalink BB spindle? A simple "Yes" or "No" will suffice. And, once again, have you personally ever experienced the loosening and subsequent spindle damage you so often describe when using an Octalink crank/BB? |
#28
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Advice regarding Octalink BB/Crank
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#29
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Advice regarding Octalink BB/Crank
On Jun 9, 10:30*am, Peter Cole wrote:
wrote: On Jun 9, 4:38 am, Chalo wrote: the tool I am refering too is http://www.parktool.com/products/det...13&item=TW%2D1 I have heard it called a strain guage, *I have seen this type of tool at at a local automotive store for a lot less than other types of torque wrenches. I am trying to help the OP. It's a "beam" type torque wrench, a strain gauge is something quite different. uhhh, you say normal use- *I indicated under varying environmental conditions to suggest more exceptional use- don't try to put words in my mouth to try to make a point, K-o ? "varying environmental conditions" sounds like rain to me. Bit vague, no? beam type; thanks I'll try to remember that; more than rain, -10c winter riding from warm indoor environment and back again, numerous thermal expansion/contraction cycles, up-hill sprint/hill repeats- all things considered, a consequent loosening or play developing after several months was understandable |
#30
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Advice regarding Octalink BB/Crank
On Jun 9, 12:09*pm, RonSonic wrote:
On 09 Jun 2009 15:05:13 GMT, wrote: Chalo Colina wrote: Again, the only torque the BB spindle carries is that from the left crank, right crank torque going directly into the chain. You are aware of the following, because I have seen you say so: Cranks can be torqued one against the other in either direction. This torque necessarily transmits through the spindle. But backing up a bit, for pedaling forces the spindle transmits torque from the left crank only. *Standing on both pedals with the right foot forward is the only time reverse torque is transmitted through the spindle. Landing from a jump or drop in a standing position exerts higher momentary torque than any amount of pedaling. I don't think that is correct, because only half the rider's weight is on each pedal. *The legs not being rigid, absorb acceleration forces putting less force on the pedals than they do on steep climbing while pulling up on the opposite pedal. *That causes greater force on pedals than a jump. That one rates a "huh?" I can jump from a 5 foot high wall. I cannot jump up a 5 foot high wall. Landing from a jump involves far more force than the legs can generate. Legs may absorb landing force relative to the person's head, but not from the pov of the surface (or pedals) being landed upon.- Hide quoted text - - Show quoted text - people use their arms to absorb a lot of the shock from a jump- I notice a lot less jarring jumping with a bike than jumping down a few stairs |
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