Ash1984 Posted March 13, 2008 Report Share Posted March 13, 2008 I have spent over an hour searching the forum for an explanation of what BB rise and drop is and how to measure it - no joy.Back in the day you had BB height - measured from the ground to the centre of the BB cup when the bike was fully built up, I have no idea where the idea of 'rise' and 'drop' comes from.I could make a guess in that its the difference between the rear axle height and the centre of the BB when the bike is built up, however when looking at pictures of bikes with apparently 50mm rise it doesn’t seem to be the case.It all started out looking up what stems and bars are about nowadays and seeing people talking about thing like, 'oh your BB rise is 10, the top tube is 1010 so the Q factors will make your porridge go cold, therefore you need a 110mm stem with 10deg rise'. I take it its not a case of massive DH bar with massive rise and a stubby short no rise stem any more? (Maybe it never was but that’s what I've always rode! )How does frame geometry work in basic terms. i.e does a high BB mean longer stems are needed?By the way I'm riding a Pashley 26mHz, I need a new bar and stem (lighter stem and wider bar). The current set up is one of them massive CNC world force stems - about 80mm with 10-20deg rise and a 24/7 bar, seems too narrow and heavy as you like - about 1 inch rise.... suggestions anyone? I have been guessing about a 100mm with 10 rise stem should do it along with a cheapy wide bar like the Onzas and that?Many thanks, sorry if I have missed some old post somewhere explaining all this Quote Link to comment Share on other sites More sharing options...
El Cristoff Posted March 13, 2008 Report Share Posted March 13, 2008 (edited) BB rise is measure from hub to hub, then from the imagnary line to the center of the BB shell.if that makes sence. Edited March 13, 2008 by El Cristoff Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted March 13, 2008 Report Share Posted March 13, 2008 Paint is goood...As for new bar and stem... it kinda depends how you want the bike to ride - more like a 'trials bike' or more like a spinny BMXy type. Longer/lower front ends lend themselves (generally) to more trialsy moves and shorter/higher to BMXy stuff Quote Link to comment Share on other sites More sharing options...
Ash1984 Posted March 13, 2008 Author Report Share Posted March 13, 2008 Thanks for that chaps, makes sense now!Big thanks to Adam for the very detailed paint diagram that puts CAD images to shame, i like the KISS approach Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted March 13, 2008 Report Share Posted March 13, 2008 BB Rise On WikiAfter searching for hours the other day,i found this in wiki!Ben Quote Link to comment Share on other sites More sharing options...
Ash1984 Posted March 13, 2008 Author Report Share Posted March 13, 2008 Barsteward Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted March 13, 2008 Report Share Posted March 13, 2008 I am no such thing Quote Link to comment Share on other sites More sharing options...
JonMack Posted March 13, 2008 Report Share Posted March 13, 2008 I usually measure from floor to centre of rear axle, then floor to centre of BB, then take the first measurement away from the second. Quote Link to comment Share on other sites More sharing options...
Alex Dark Posted March 13, 2008 Report Share Posted March 13, 2008 i do the same thing....for your pash id buy a fairly cheap 100mm long stem with a bit of rise..then pick up some nice risers like some try-alls Quote Link to comment Share on other sites More sharing options...
Muel Posted March 13, 2008 Report Share Posted March 13, 2008 Slacken the hubs bolts off on one side of the bike, just enough to get a piece of string in, then tie it tight from one bolt to the other with the wheels in line.Then measure from the string to the bb. Quote Link to comment Share on other sites More sharing options...
Ash1984 Posted March 14, 2008 Author Report Share Posted March 14, 2008 Eye I'm looking at a cheap 100mm stem - like £5 just to get a feel for it, might buy a few cheap stems of differnt sizes just to get a feel for them. Quote Link to comment Share on other sites More sharing options...
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