hiya, ive been trying to fit a set of retro middleburn rs2 cranks to my 1995 orange p7 and does any one know what size of bottom bracket should be fitted so that these will not rub and the front mech will work ive heard a 68 x122 is the way to go but before i start ebaying thougt best to double check.Thanks all.Stu
1995 P7 trying to fit middlebirn rs2 cranks help with BB
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You'll need to go longer than that - Mine needed a 130mm for a 50mm chainline. 122.5 wasn't enough;
viewtopic.php?f=1&t=183318&hilit=hope+bottom+bracket
HTH
viewtopic.php?f=1&t=183318&hilit=hope+bottom+bracket
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Unlikely... but was it a compact only mech?
I assume you do know how to adjust the travel stops on the mech?
I assume you do know how to adjust the travel stops on the mech?
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They're meant to use a 124mm, but I've used a 122.5mm on a few different bikes , and it's been fine. The 122.5mm is the limit though! Just thinking, the Hope BB I use on them has an slightly adjustable chainline, which is probably why a 122.5mm works.
They're meant to use a 124mm, but I've used a 122.5mm on a few different bikes , and it's been fine. The 122.5mm is the limit though! Just thinking, the Hope BB I use on them has an slightly adjustable chainline, which is probably why a 122.5mm works.
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yea i used a hope on it and faffed around ,got it to fit but couldnt for the life of me to get the original black 95 circa lx mech to play ball at all which does work with the compact cheapo one down from stx circa 2008 crankset i put on ok am only saving what 2-300 grammes but you loose the whole retro thing....
so basically whats needed is a 68 124 b/b and i guess a DX era front mech ? or are there new front mech that shift non compact mechs ?
yea i used a hope on it and faffed around ,got it to fit but couldnt for the life of me to get the original black 95 circa lx mech to play ball at all which does work with the compact cheapo one down from stx circa 2008 crankset i put on ok am only saving what 2-300 grammes but you loose the whole retro thing....
so basically whats needed is a 68 124 b/b and i guess a DX era front mech ? or are there new front mech that shift non compact mechs ?
http://www.ebay.co.uk/itm/POWERPRO-BB-7 ... 540f63f599
found a B/B darn wish it was a TI one now for a front mech.any suggestions ..thanks
found a B/B darn wish it was a TI one now for a front mech.any suggestions ..thanks
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I don't see why the front mech should be unhappy. The only thing that would upset a front mech is that the chainrings weren't evenly spaced across the shift range. I have experienced this problem when mixing chainrings from different sources as they differ in thickness which then upsets the mechs accuracy because the shifter won't stop exactly where you want it to. Titanium rings give a similar problem because they are thinner, thus placing the chainline closer to the BB, which again upsets the accuracy of the shifter ( when mixed with alloy rings of course). I've also had chainring spacers that weren't the right width, and yes, 1mm makes a big difference down there!
So, use whatever mech you want (I happily run M900 XTR on mine) but ensure the rings are evenly spaced.
I don't see why the front mech should be unhappy. The only thing that would upset a front mech is that the chainrings weren't evenly spaced across the shift range. I have experienced this problem when mixing chainrings from different sources as they differ in thickness which then upsets the mechs accuracy because the shifter won't stop exactly where you want it to. Titanium rings give a similar problem because they are thinner, thus placing the chainline closer to the BB, which again upsets the accuracy of the shifter ( when mixed with alloy rings of course). I've also had chainring spacers that weren't the right width, and yes, 1mm makes a big difference down there!
So, use whatever mech you want (I happily run M900 XTR on mine) but ensure the rings are evenly spaced.
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well wiped the old bottom bracket out today from the p7 which currently has a shimano cheapo compact chainset from about 5 years ago and its running the original circa 95 black lx front mech with a 122.5 un 52 bb and that set up works fine but looks wrong ..so thought id just put the rs2 on and after faffing about for an hour i even put a new xtr m961 mech on and sure enough only way this set up is going to work is to use a much longer bb as i now see the issue is the rs sits closer to the frame /chainline ....one thing that has surprised me is the weight difference in new and high end retro stuff is not that noticable however i found the old 95 lx mech feels lighter than the xtr thats 10 years newer ....anyhoo ebay search for a long bb now without spending a fortune...anyhoo chuffin bikes pita
well wiped the old bottom bracket out today from the p7 which currently has a shimano cheapo compact chainset from about 5 years ago and its running the original circa 95 black lx front mech with a 122.5 un 52 bb and that set up works fine but looks wrong ..so thought id just put the rs2 on and after faffing about for an hour i even put a new xtr m961 mech on and sure enough only way this set up is going to work is to use a much longer bb as i now see the issue is the rs sits closer to the frame /chainline ....one thing that has surprised me is the weight difference in new and high end retro stuff is not that noticable however i found the old 95 lx mech feels lighter than the xtr thats 10 years newer ....anyhoo ebay search for a long bb now without spending a fortune...anyhoo chuffin bikes pita
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