tag:blogger.com,1999:blog-13887692.post6327840509153151405..comments2021-06-08T12:13:28.399-04:00Comments on Cozy Beehive: 52x12 vs 52x11 Gearing : A Look At Chordal ActionRon Georgehttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comBlogger11125tag:blogger.com,1999:blog-13887692.post-47498839509710756702010-01-31T22:10:24.724-05:002010-01-31T22:10:24.724-05:00Rooster : Not sure what a discussion on chains hav...Rooster : Not sure what a discussion on chains have to do with chickens, but oh well, I did check it out. :) Not a great way to solicit interest though :)Unknownhttps://www.blogger.com/profile/12256394060474969622noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-47211579853045708632010-01-31T21:59:48.598-05:002010-01-31T21:59:48.598-05:00http://roostershamblin.wordpress.com/ would you...http://roostershamblin.wordpress.com/ would you please spend a few minutes of your time and check out my new blog. I am a farmer who has been raising more than 50 breeds of chickens for forty years.Rooster Shamblinhttp://roostershamblin.wordpress.com/noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-29569520989291247112010-01-29T15:05:36.592-05:002010-01-29T15:05:36.592-05:00To understand how power losses occur in chains, yo...To understand how power losses occur in chains, you have to look at what the chain goes through on its way to transfer power from the chainring to the sprocket. The article here explores one of the mechanisms of wear and perhaps efficiency loss. Others are there, although minimal, like friction in the links of the chain and if we assume friction does work, then there is a power loss factor from that if you calculate the work done per chain rotations etc. All in all, its a pain in the ass to crunch these numbers out! :)Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-10067829551184129012010-01-29T10:22:24.128-05:002010-01-29T10:22:24.128-05:00Hi - I've been having a long time argument wit...Hi - I've been having a long time argument with friends on gear inches and efficiency. Is 60 gear inches on the inside chainring any different than a 60 inch with large chainring combination, assuming no strange chain alignments?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-64791294878658730532010-01-28T15:54:45.505-05:002010-01-28T15:54:45.505-05:00Math is hard.
52t chain rings are for pansies.
G...Math is hard.<br /><br />52t chain rings are for pansies.<br /><br />Go for a bike ride.<br /><br />Xo,<br /><br />Cousin BrucieAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-91927455234689177822010-01-28T15:34:51.192-05:002010-01-28T15:34:51.192-05:00chordal action causes chain whip and most of your ...chordal action causes chain whip and most of your sprocket wear happens then.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13887692.post-70517730759167274822010-01-28T14:55:44.051-05:002010-01-28T14:55:44.051-05:00@ DJ : No I don't have a functional relationsh...@ DJ : No I don't have a functional relationship between chordal action and tooth wear, although it'd be interesting to have one and put it up on the blog.<br /><br />It doesn't seem too wrong to assume that repeated chordal rise and fall of the chain in such small sprockets over many months of riding can accelerate tooth wear if those gears are used frequently. Afterall, its the roller impacting on the tooth.<br /><br />I personally know a chap who rides in such high gears (52-15, 52-12 etc) more than 70% of the time, even to go 15 mph. It puzzles me, did he forget that there were 9 other gears before that? :)Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-74183316543565566092010-01-28T14:41:51.999-05:002010-01-28T14:41:51.999-05:00Gentlemen : I made an idiotic error, in 52/12 gear...Gentlemen : I made an idiotic error, in 52/12 gear ratio, its actually 473 RPM as opposed to 482 (I may have done 53/12) so I just edited that part and consequently the graph for 11-T changes but yeah delta V doesn't change at all.<br /><br />Yes it is a constant cadence analysis, pretty simple actually. What I wanted to highlight though is that with smaller cogs like the 12T and 11T, the delta in chain velocity each cycle doesn't change and it has been well established that with sprocket sizes this small, chordal action is 3.5% to 4% and it progressively becomes smaller as the number of teeth on the cogs increase and is negligible for sprockets with 20-25 teeth and more. So if you drew out a graph with number of teeth on x axis and % change in chain velocity on your y axis, you get an exponentially decreasing graph.<br /><br /><br /><br />@Hightower : I see where you're getting at. <br /><br />Let's assume the chain is 95% efficient (not a bad assumption). Now let's say I want to sprint in a 52-12 or a 52-11 to achieve a top speed of 35 mph. I will have to pedal at 110 RPM in 52-12 as opposed to 100-101 RPM in 52-11. Multiplying those RPM adjustments to yield the chain linear speeds with articulation angle variation changes my Vmax and Vmin in both cases, however the delta V doesn't change. Its a law of physics for gearing :) What is better between a 12 and an 11? You get higher speed for lesser RPM in 11T, which may probably mean that you you won't raise your heart rate as much to achieve the same speed but I can't describe all that physiological stuff very well.Ron Georgehttps://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-79123918470948976462010-01-28T13:59:20.036-05:002010-01-28T13:59:20.036-05:00Whoops! Correction: shifting to a smaller chainri...Whoops! Correction: shifting to a smaller chainring and increasing cadence keeps the same chain speed and same tension. There's nothing to cancel. The chain speed-tension tradeoff comes when the road grade changes at the same gear, changing cadence at the same power. Sorry for the clutter.djconnelhttps://www.blogger.com/profile/01484858820878605035noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-83070242797010776912010-01-28T13:39:55.020-05:002010-01-28T13:39:55.020-05:00A few points.... one of which Hightower just made....A few points.... one of which Hightower just made.<br /><br />One is the assumption of constant cadence. I think this makes the most sense if you assume the same gear ratio (for example, 44/11 versus 48/12) With a fixed chainring, I'd scale the cadence in inverse proportion to the cog (ie constant wheel rotation rate).<br />With this assumption, the chain is engaging teeth more slowly at the rear cog. On the other hand, there's fewer teeth, so each tooth is engaged at the same rate. So if you're calculating cog wear, your analysis actually applies more to the case of constant wheel speed than constant cadence.<br />That said, how does the speed fluctuation relate to wear? Do you have a functional relationship?<br /><br />In my simple-mindedness I'd have been tempted to adopt a model where wear is proportional to chain tension times the amount the chain bends upon contacting the the tooth times the rate at which the tooth engages chain links.<br /><br />Chain tension = P / (C × Nf × L), where P is power, C is the cadence, Nf is number of chainring teeth, and L is the chain pitch = 1/2 inches.<br />bending angle = twice articulation angle = 2 π / Nr, where Nr is the number of cog teeth.<br />Rate at which teeth get engaged = C × Nf / Nr²<br /><br />Multiplying these yields:<br /><br />2 π P / (L × Nr³)<br /><br />which is curious in that it depends neither on the chainring teeth nor the cadence. Shifting to a smaller chainring and increasing cadence increases chain speed and decreases tension, and the effects cancel, assuming wear is proportional to the product.<br /><br />But I think you have better training in this area than I do. My model is surely too simple.djconnelhttps://www.blogger.com/profile/01484858820878605035noreply@blogger.comtag:blogger.com,1999:blog-13887692.post-86620060618683028422010-01-28T13:31:05.124-05:002010-01-28T13:31:05.124-05:00There is a larger change in velocities, but you wi...There is a larger change in velocities, but you will be going faster. If you look at the ratio of gear inches between the (52x12)/(52x11) you get ~.91. Then if you look at the ratio of the delta V's you get ~.83. So what would the ratio be if you adjusted the RPM to yield the same speed. I imagine in delta V the difference would be much less between the gears.Hightowerhttps://www.blogger.com/profile/02857505318918326021noreply@blogger.com