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I'm really scared y'all are going to yell at me...
Ok, so I "finished" the old Peugeot to fixie convert today. Truth be
told, I need a shorter bottom bracket spindle, but that'll come later (after my next paycheck). So, to adjust the chainline to pretty darn good, I used spacers with the chainwheel on the inside of the spider. All in all, the chainline was off by about 2 mm (I know...I know). I used old stack bolts from my BMX bike, and they seemed to work fairly well. I had to turn them around since the female end didn't fit through the spacers (shoddier...it just gets shoddier). Then, I'm taking it out on a test run to the center of campus and I'm spinning pretty fast down a decent hill. PING! Two of the stack bolts fly off. scary scary scary. I slam on my front brake (my buddy, from now on) and sure enough...they're gone. My theory is this: I didn't tighten them enough and with the spacers, they really couldn't thread enough. Will normal new short stack bolts be long enough to deal with the spacers that I need for now??? Should I get double chainring stack bolts and put more spacers on until I get the new BB spindle??? thanks already...I'm still recovering from seeing my life before my eyes. \\paul -- Paul M. Hobson Georgia Institute of Technology ..:change the words numbers if you want to reply to me:. |
#2
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I'm really scared y'all are going to yell at me...
In article , Paul Hobson
wrote: Ok, so I "finished" the old Peugeot to fixie convert today. Truth be told, I need a shorter bottom bracket spindle, but that'll come later (after my next paycheck). So, to adjust the chainline to pretty darn good, I used spacers with the chainwheel on the inside of the spider. All in all, the chainline was off by about 2 mm (I know...I know). I used old stack bolts from my BMX bike, and they seemed to work fairly well. I had to turn them around since the female end didn't fit through the spacers (shoddier...it just gets shoddier). Then, I'm taking it out on a test run to the center of campus and I'm spinning pretty fast down a decent hill. PING! Two of the stack bolts fly off. scary scary scary. I slam on my front brake (my buddy, from now on) and sure enough...they're gone. My theory is this: I didn't tighten them enough and with the spacers, they really couldn't thread enough. Will normal new short stack bolts be long enough to deal with the spacers that I need for now??? Should I get double chainring stack bolts and put more spacers on until I get the new BB spindle??? Here are few thoughts and observations. On all of my cranks the chainring bolts engage enough of the nut so that the bolt ends (threaded portion) are just shy of being flush with the nut (as viewed from the inner side of the chainring). If your chainring bolt/nut relation is similar, I'd hazard that enough of the nut has been engaged by the bolt. That said, I'm skeptical that your BMX (i.e., single chainring) stack bolts, when used with chainring spacers, could properly engage enough of the bolts' threads. Relating to the subject, how much have you spaced your chainring to the insider of the spider? The less distance the better as greater spacing will tend to promote a shearing action (correct term?) on the chainring bolts. Perhaps this, in conjunction with your reversal of the stack bolts), and their used condition, may be behind the liberation of your fasteners: Are the bolts actually loosening or is the lip of the nut shearing off and the bolt pulling through the spider? This has happened to me on occasion with aged, overtightened - and correctly orientated - stack bolts. I suggest you start from scratch. Get spacers that allow for the proper orientation of the stack bolts http://sheldonbrown.com/harris/singlespeed.html#cranks and dual chainring stackbolts, then give it another try. Though this time, consider avoiding racing down hills on the maiden test run!! Luke |
#3
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I'm really scared y'all are going to yell at me...
"Luke" a écrit dans le message de news:
... In article , Paul Hobson wrote: Ok, so I "finished" the old Peugeot to fixie convert today. Truth be told, I need a shorter bottom bracket spindle, but that'll come later (after my next paycheck). So, to adjust the chainline to pretty darn good, I used spacers with the chainwheel on the inside of the spider. All in all, the chainline was off by about 2 mm (I know...I know). I used old stack bolts from my BMX bike, and they seemed to work fairly well. I had to turn them around since the female end didn't fit through the spacers (shoddier...it just gets shoddier). Then, I'm taking it out on a test run to the center of campus and I'm spinning pretty fast down a decent hill. PING! Two of the stack bolts fly off. scary scary scary. I slam on my front brake (my buddy, from now on) and sure enough...they're gone. My theory is this: I didn't tighten them enough and with the spacers, they really couldn't thread enough. Will normal new short stack bolts be long enough to deal with the spacers that I need for now??? Should I get double chainring stack bolts and put more spacers on until I get the new BB spindle??? Here are few thoughts and observations. On all of my cranks the chainring bolts engage enough of the nut so that the bolt ends (threaded portion) are just shy of being flush with the nut (as viewed from the inner side of the chainring). If your chainring bolt/nut relation is similar, I'd hazard that enough of the nut has been engaged by the bolt. That said, I'm skeptical that your BMX (i.e., single chainring) stack bolts, when used with chainring spacers, could properly engage enough of the bolts' threads. Relating to the subject, how much have you spaced your chainring to the insider of the spider? The less distance the better as greater spacing will tend to promote a shearing action (correct term?) on the chainring bolts. Perhaps this, in conjunction with your reversal of the stack bolts), and their used condition, may be behind the liberation of your fasteners: Are the bolts actually loosening or is the lip of the nut shearing off and the bolt pulling through the spider? This has happened to me on occasion with aged, overtightened - and correctly orientated - stack bolts. I suggest you start from scratch. Get spacers that allow for the proper orientation of the stack bolts http://sheldonbrown.com/harris/singlespeed.html#cranks and dual chainring stackbolts, then give it another try. Though this time, consider avoiding racing down hills on the maiden test run!! Luke I assume you tightened each one a bit before proceeding to the next bolt to tighten (not an adjacent one), until all were done? Make sure you retighten the bolts after riding a bit. |
#4
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I'm really scared y'all are going to yell at me...
Paul Hobson wrote: Ok, so I "finished" the old Peugeot to fixie convert today. Truth be told, I need a shorter bottom bracket spindle, but that'll come later (after my next paycheck). So, to adjust the chainline to pretty darn good, I used spacers with the chainwheel on the inside of the spider. All in all, the chainline was off by about 2 mm (I know...I know). I used old stack bolts from my BMX bike, and they seemed to work fairly well. I had to turn them around since the female end didn't fit through the spacers (shoddier...it just gets shoddier). Then, I'm taking it out on a test run to the center of campus and I'm spinning pretty fast down a decent hill. PING! Two of the stack bolts fly off. scary scary scary. I slam on my front brake (my buddy, from now on) and sure enough...they're gone. My theory is this: I didn't tighten them enough and with the spacers, they really couldn't thread enough. Will normal new short stack bolts be long enough to deal with the spacers that I need for now??? Should I get double chainring stack bolts and put more spacers on until I get the new BB spindle??? thanks already...I'm still recovering from seeing my life before my eyes. Get track chainring bolts, mount the single ring onto the inside of the crank. |
#5
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I'm really scared y'all are going to yell at me...
Qui si parla Campagnolo wrote:
Paul Hobson wrote: I'm a bad fixie mechanic thanks already...I'm still recovering from seeing my life before my eyes. Get track chainring bolts, mount the single ring onto the inside of the crank. The chainring is on the inside already, and had spacers pushing it more towards the inside. I'm really considering calling up Harris right now and getting a new BB spindle. \\paul -- Paul M. Hobson Georgia Institute of Technology ..:change the words numbers if you want to reply to me:. |
#6
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I'm really scared y'all are going to yell at me...
In article , Paul Hobson
wrote: The chainring is on the inside already, and had spacers pushing it more towards the inside. I'm really considering calling up Harris right now and getting a new BB spindle. \\paul Paul, I caution against haste. The spindle length you require to ensure a proper chainline (sans spacers) with your current setup may be less than that which your crankset will accept: your square taper crank may but up against the BB's mounting ring, precluding a proper press fit. Of course, this is contingent on the specs of the crankset, so exercise due diligence beforehand and determine if this constraint applies in your case -- doing so will spare you future headaches. My favourite - and cheap! - cranks for fixie conversions? Old Shimano RSX Dual chainring cranksets. I've installed them on spindle's as short as 103mm. Luke |
#7
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I'm really scared y'all are going to yell at me...
Luke wrote:
In article , Paul Hobson wrote: The chainring is on the inside already, and had spacers pushing it more towards the inside. I'm really considering calling up Harris right now and getting a new BB spindle. \\paul Paul, I caution against haste. The spindle length you require to ensure a proper chainline (sans spacers) with your current setup may be less than that which your crankset will accept: your square taper crank may but up against the BB's mounting ring, precluding a proper press fit. Of course, this is contingent on the specs of the crankset, so exercise due diligence beforehand and determine if this constraint applies in your case -- doing so will spare you future headaches. My favourite - and cheap! - cranks for fixie conversions? Old Shimano RSX Dual chainring cranksets. I've installed them on spindle's as short as 103mm. Luke Luke...thanks for the cautions. I'm really excited about this and I get quite easily carried away. Currently I've a Stronglight 120 mm spindle in the BB. I turned it around and put 3 mm spacers in there today (had 1.5 mm yesterday. I'd say the chainline is much better (1 mm off?). The shop had much more spacers, so I feel that 4 would get a very nice chainline. The problem I'm now having is getting a proper and uniform chain tension around the entire 6.2832 radian path. I'm thinking I need to drive over to the rich old uncle's house and use his stand so that I can spine the cranks/wheel and keep the bike upright. \\paul -- Paul M. Hobson Georgia Institute of Technology ..:change the words numbers if you want to reply to me:. |
#8
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I'm really scared y'all are going to yell at me...
In article , Paul Hobson
wrote: Luke...thanks for the cautions. I'm really excited about this and I get quite easily carried away. Currently I've a Stronglight 120 mm spindle in the BB. I turned it around and put 3 mm spacers in there today (had 1.5 mm yesterday. I'd say the chainline is much better (1 mm off?). The shop had much more spacers, so I feel that 4 would get a very nice chainline. The problem I'm now having is getting a proper and uniform chain tension around the entire 6.2832 radian path. I'm thinking I need to drive over to the rich old uncle's house and use his stand so that I can spine the cranks/wheel and keep the bike upright. \\paul If I read you correctly, the chain tension varies with respect to the crankset position. Even with fixie specific hardware this is the rule; there isn't a chainring (regardless of price) that's perfectly symmetrical; expect slight discrepancies in chain tension as the cranks rotate. Set the chain tension while the cranks are positioned in their 'high spot' to avoid chain binding, and don't unduly trouble yourself. This, of course, is assuming that the chainring or the crank's spider is not deformed through impact or mechanical misadventure; placing them on glass should determine whether there are significant shortcomings in this regard. Hope ya enjoy the fixie; they are fun! And once you master trackstands, the girls on campus will be impressed!!! ;-) Luke |
#9
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I'm really scared y'all are going to yell at me...
Luke wrote:
In article , Paul Hobson wrote: The chainring is on the inside already, and had spacers pushing it more towards the inside. I'm really considering calling up Harris right now and getting a new BB spindle. \\paul Paul, I caution against haste. The spindle length you require to ensure a proper chainline (sans spacers) with your current setup may be less than that which your crankset will accept: your square taper crank may but up against the BB's mounting ring, precluding a proper press fit. Of course, this is contingent on the specs of the crankset, so exercise due diligence beforehand and determine if this constraint applies in your case -- doing so will spare you future headaches. My favourite - and cheap! - cranks for fixie conversions? Old Shimano RSX Dual chainring cranksets. I've installed them on spindle's as short as 103mm. Luke Oh...and look at this: http://sheldonbrown.com/harris/bottombrackets.html scroll down to "Old-style Cup-and-Cone Bottom Bracket Parts" and this: http://sheldonbrown.com/harris/frenc...ks.html#bottom scroll down to "T.A. Bottom Bracket Spindles/Axle" What is different about these spindles (aside from $35)? Looking at my spindle, it's shaped exactly like the first link, and its dimensions match that exactly. But, the website and shop make me think that I should be replacing a Stronglight 120 mm spindle with the TA Spindles? SHELDON HELP!!! \\paul -- Paul M. Hobson Georgia Institute of Technology ..:change the words numbers if you want to reply to me:. |
#10
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I'm really scared y'all are going to yell at me...
Paul Hobson wrote: Qui si parla Campagnolo wrote: Paul Hobson wrote: I'm a bad fixie mechanic thanks already...I'm still recovering from seeing my life before my eyes. Get track chainring bolts, mount the single ring onto the inside of the crank. The chainring is on the inside already, and had spacers pushing it more towards the inside. I'm really considering calling up Harris right now and getting a new BB spindle. \\paul No shops local that have BBs?? Not really very exotic. -- Paul M. Hobson Georgia Institute of Technology .:change the words numbers if you want to reply to me:. |
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