Greetings Posted August 26, 2006 Report Share Posted August 26, 2006 Ok, so here's the problem. I'm looking for a gear ratio which in combination with 372mm CS will give me a tight chain without the need of using a chain tensioner. I have calculated that a 18:16T gear ratio should give me an ideal tension but as we all know, even a 0,5mm error in these calculations will result in either a loose chain or not being able to get it on. Any gear ratio between 1.5:1 and 1.22:1 is acceptable. Ideas? Quote Link to comment Share on other sites More sharing options...
dave33 Posted August 26, 2006 Report Share Posted August 26, 2006 measure the length from bb to axle x2 add the rad of both cogs= what your after Quote Link to comment Share on other sites More sharing options...
Greetings Posted August 26, 2006 Author Report Share Posted August 26, 2006 (edited) Unfortunately not, because the chain is at an angle. It just gets too complicated. Obviously calculating the length of the blue line is dead easy but it's the precision of the measurements that's an issue.Edit: maybe somebody knows of some working gear ratios? How is a 18:16 on an Adamant? Edited August 26, 2006 by Inur Quote Link to comment Share on other sites More sharing options...
Rich Pearson Posted August 26, 2006 Report Share Posted August 26, 2006 Talk to fatmike, he's pretty clued up on gear ratios. I'm running singlespeed on my Leeson with no tensioner and its really just a case of playing around with different chains and sproket combinations.Rich Quote Link to comment Share on other sites More sharing options...
mat hudson Posted August 26, 2006 Report Share Posted August 26, 2006 a bit of string? Quote Link to comment Share on other sites More sharing options...
Trials Punk Posted August 27, 2006 Report Share Posted August 27, 2006 Talk to fatmike, he's pretty clued up on gear ratios. I'm running singlespeed on my Leeson with no tensioner and its really just a case of playing around with different chains and sproket combinations.RichIs yours 24"If so what chain, and chainrings are you running. I'm quite tempted at trying this, ther'd be less in the way. Quote Link to comment Share on other sites More sharing options...
joker Posted August 27, 2006 Report Share Posted August 27, 2006 If you have a standard cassette hub, you could use spacers to move the rear sprocket side to side to fine tune your chain tension if its roughly the right length. I know it won't give you an ideal chainline, but unless your very lucky or have an eccentric bb your gonna struggle whatever you do. Quote Link to comment Share on other sites More sharing options...
Deonn h Posted August 27, 2006 Report Share Posted August 27, 2006 Surely the chain will stretch after a while and make it slack again? Quote Link to comment Share on other sites More sharing options...
Danny Kearns Posted August 27, 2006 Report Share Posted August 27, 2006 Surely the chain will stretch after a while and make it slack again?Depends if it is a brand new chain to start with.Dan. Quote Link to comment Share on other sites More sharing options...
ManxTrialSpaz Posted August 28, 2006 Report Share Posted August 28, 2006 (edited) As mentioned,,,string?Edit: Or one of those clothing tape measures--the fabriccy bendy ones? Edited August 28, 2006 by ManxTrialSpaz Quote Link to comment Share on other sites More sharing options...
ben_travis Posted August 28, 2006 Report Share Posted August 28, 2006 Depends if it is a brand new chain to start with.Dan.but if a chain is pre-stretched or has been previously used then it is bound to snap sometime soon. its pretty much guaranteed. and if you use a brand new chain, it will stretch meaning that gear will become slack.also while running it tight you are putting more stresses on the freehub which in turn will probably f**k your hub internals.all for the sake of loosing a tensioner?sillllllly Quote Link to comment Share on other sites More sharing options...
ManxTrialSpaz Posted August 28, 2006 Report Share Posted August 28, 2006 Couldn't you just buy a chain, wrap it around your cogs, mark where you think it should end then fit it? Quote Link to comment Share on other sites More sharing options...
Greetings Posted August 28, 2006 Author Report Share Posted August 28, 2006 Ben: That's not quite so because mod bikes seem to be running this kind of setup and they're fine. But yeah chains can stretch a lot, even by 1-2%. It looks like Deng's idea with the horizontal dropouts isn't that bad after all. I've made myself a tiny tensioner but I don't think it will hold if I miss a sidehop, that's why I'm looking for a ratio which will work without one. Couldn't you just buy a chain, wrap it around your cogs, mark where you think it should end then fit it? Nope, because it would mean getting loads of different chainrings to get the perfect fit Looks like I'll just have to keep using a tensioner Quote Link to comment Share on other sites More sharing options...
ManxTrialSpaz Posted August 28, 2006 Report Share Posted August 28, 2006 I ment (without putting it together) just putting it around your cogs then mark the point where it would start getting slack and chain tool that section off? Quote Link to comment Share on other sites More sharing options...
ben_travis Posted August 28, 2006 Report Share Posted August 28, 2006 Ben: That's not quite so because mod bikes seem to be running this kind of setup and they're fine. But yeah chains can stretch a lot, even by 1-2%. It looks like Deng's idea with the horizontal dropouts isn't that bad after all. I've made myself a tiny tensioner but I don't think it will hold if I miss a sidehop, that's why I'm looking for a ratio which will work without one. Nope, because it would mean getting loads of different chainrings to get the perfect fit Looks like I'll just have to keep using a tensioner if you check out my adamant - http://www.trials-forum.co.uk/forum/index....showtopic=79712 , there is my custom tensioner on there (made by tom rigg) and it works amazingly. also its sprung so means that you can land on it no problem and all is gravy .take a look, and pm tom for one if you so wish. Quote Link to comment Share on other sites More sharing options...
Rich Pearson Posted August 28, 2006 Report Share Posted August 28, 2006 Is yours 24"If so what chain, and chainrings are you running. I'm quite tempted at trying this, ther'd be less in the way.Sorry mate, 26".Rich Quote Link to comment Share on other sites More sharing options...
Greetings Posted August 28, 2006 Author Report Share Posted August 28, 2006 if you check out my adamant - http://www.trials-forum.co.uk/forum/index....showtopic=79712 , there is my custom tensioner on there (made by tom rigg) and it works amazingly. also its sprung so means that you can land on it no problem and all is gravy .Looks good and well worked out I've come up with something like this, it shouldn't snap because it's thick steel but one never knows... I guess if it was twice as thick (6mm) it would withstand anything. Quote Link to comment Share on other sites More sharing options...
Trials Punk Posted August 28, 2006 Report Share Posted August 28, 2006 Looks good and well worked out I've come up with something like this, it shouldn't snap because it's thick steel but one never knows... I guess if it was twice as thick (6mm) it would withstand anything.Fair doos, thats really good. Nicely made, liking the use of the star fangled nut. I had a though whilst out riding the other day, some frame company should try and weld a tensioner boos in the middle of the chainstay on the wheel side. Make a custom tensioner to do the job. Keeps it out of the way as you hardly hit that area (much). Quote Link to comment Share on other sites More sharing options...
durkie Posted August 29, 2006 Report Share Posted August 29, 2006 why don't you try this: http://www.peak.org/~fixin/personal/fmu/php/fixmeup.php Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted August 29, 2006 Report Share Posted August 29, 2006 http://www.peak.org/~fixin/personal/fmu/php/formfmu.php Edit, oops. Quote Link to comment Share on other sites More sharing options...
BikeDotStuffAtOnzaDotCom Posted August 30, 2006 Report Share Posted August 30, 2006 (edited) It only goes down to 20T...I tried it and didn't suggest "Fix Me Up" for that reason.Does anyone else know of any others...? Edited August 30, 2006 by BikeDotStuffAtOnzaDotCom Quote Link to comment Share on other sites More sharing options...
durkie Posted August 31, 2006 Report Share Posted August 31, 2006 It only goes down to 20T...I tried it and didn't suggest "Fix Me Up" for that reason.Does anyone else know of any others...?it should go lower? i wrote to him once because it wouldn't go below 24T, and i thought he lowered it to 16t. write him an email...he'll change it. Quote Link to comment Share on other sites More sharing options...
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