The Street > The Bike Shop
Keychain woes?
Oddity:
We have nearly the same setup save for the sprocket, I have a 28t Tree and mine is the does the same thing as your video shows. Even with the shitty drive line alignment I have(wide tire accommodating frame that barely fits a 28t with loads of spacers) it feels absolutely great riding it, it's probably the smoothest setup I've ever had, no noise, no harsh spots, no random tight spots, or uneven wear on the sprocket. I say you're over thinking this and just ride it, it's a bmx bike afterall.
weedbix:
A quick blurt for anyone interested who can't work out to do it:
Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)
110 / 2 = 55mm
55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5
Middle of driver teeth is 43.5mm from centre of drops/BB
----
Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)
75 / 2 = 37.5
Say you have a 5mm sprocket with the teeth in the centre of the sprocket
5 / 2 = 2.5mm
43.5 - 37.5 = 6
6 - 2.5mm = 3.5
3.5mm of spacing between BB bearing and that sprocket to align it with driver
montymitch:
--- Quote from: Professor Horatio Hufnagel on May 03, 2015, 05:25:15 AM ---A quick blurt for anyone interested who can't work out to do it:
Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)
110 / 2 = 55mm
55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5
Middle of driver teeth is 43.5mm from centre of drops/BB
----
Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)
75 / 2 = 37.5
Say you have a 5mm sprocket with the teeth in the centre of the sprocket
5 / 2 = 2.5mm
43.5 - 37.5 = 6
6 - 2.5mm = 3.5
3.5mm of spacing between BB bearing and that sprocket to align it with driver
--- End quote ---
Thanks for that. It seems to me that there are always issues that prevent a perfect chain alignment. Chainstay clearance, BB width vs spindle length issues, and the less than perfect alignment of the whole rear triangle often (not always) make chain line a secondary issue.
As for the bike, I've been riding it and it isn't smoothing out as well as I'd like. The chain is popping every once in a while, which messes with my head since the last time (different bike) my chain made popping noises it broke three hard cranks later and sent me over the bars.
stevefromtexas:
Elite 9 tooth tree 28 mine works fine
G:
--- Quote from: Professor Horatio Hufnagel on May 03, 2015, 05:25:15 AM ---A quick blurt for anyone interested who can't work out to do it:
Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)
110 / 2 = 55mm
55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5
Middle of driver teeth is 43.5mm from centre of drops/BB
----
Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)
75 / 2 = 37.5
Say you have a 5mm sprocket with the teeth in the centre of the sprocket
5 / 2 = 2.5mm
43.5 - 37.5 = 6
6 - 2.5mm = 3.5
3.5mm of spacing between BB bearing and that sprocket to align it with driver
--- End quote ---
This is great, but it assumes that the frame is straight and very often they aren't! I would always suggest checking with a straight edge too if at all possible.
:)
G.
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