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#21
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff
wrote: On Mar 13, 10:16*am, wrote: On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff wrote: On Mar 12, 5:46*pm, jim beam wrote: Jeff wrote: On Mar 12, 2:47 pm, wrote: On Mar 12, 5:38 pm, Jeff wrote: I just bought a new carbon road bike frame, and when I measured the rear triangle, I found it offset 6mm to the left. [snip] the wheel is centered because of spacers on the axle ? how did you measure to determine the offset ? care to name the manufacturer of the frame ? I used the rear wheel from my current road bike. *The rear spacing on the carbon frame is correct (130mm) so the wheel goes right in and is centered left/right in the triangle. *Looks to me like the whole rear tirangle was laid up wrong (jigging error) at the factory... I measured the offset using a Park frame jig that grabs the frame at the BB and has an adjustable "slider" arm (similar to the one on the Park rear derailleur hanger tool) that you can adjust to pick up the desired part of the frame. *The you reverse the frame (without changing the slider arm setting) and pick up the same point on the other side of the frame. *This is a nice heavy-duty stand that makes coldsetting steel frames as easy as that operation can get. *(I'm not sure Park makes that stand any longer -- couldn't find it on their website.) if it's the tool i think it is, are you measuring to the outside or the inside of the drops? *if you're measuring to the outside, you can easily measure a difference, yet the frame is perfectly straight. *different thickness drops, etc. *what matters is that the two wheels are centered wrt each other, and that's measured on the *inside* of the drops. I guess I could take my current steel frame and introduce a similar 6mm misalignment to see if I can feel the offset when I ride it, but I was hoping that someone would say "Nah, you won't feel it" or "Yeah, it will be unrideable" to save me the work and mental anguish of coldsetting an error into a perfectly good frame... fwiw, i've seen frames with different thickness rear drops set "centered" for their outside, not their inside, and thus they were off-center. *apparently it's a simple mistake to make. and yes, it does make a difference to ride. Thank you for pointing that out -- I'll measure the dropout thickness this evening. *The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. *I still think that is a lot... Dear Jeff, What's the alignment on your current bike on the same Park jig? Cheers, Carl Fogel Hello Carl! When I built my current steel bike, I cold set it on the same jig for equal measurments on each dropout. I built it with Campy dropouts which are the same thickness on the left and right... That was some years ago, but I haven't crashed the bike (or backed into it with a car!) so I assume it is still square. Dear Jeff, Sounds reasonable to me. I see some vague concerns in this thread, but I can't help wondering if anyone can detect a 3.7 mm axle offset by just riding the bicycle. Apart from the natural wish to have the damn thing dead center, since it's brand-new, what would a 3.7 mm offset actually do, assuming that the wheel spins and the pedals turn without hitting the frame? Make the bike pull to one side? If so, which side? Increase rolling resistance? Make it more prone to shimmy? I'm not arguing, just wondering what the specific expectations are. Cheers, Carl Fogel |
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#22
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Mar 13, 1:29*pm, " wrote:
Thank you for pointing that out -- I'll measure the dropout thickness this evening. *The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. *I still think that is a lot... Note that it would very easy to be measuring _twice_ the alignment error. If you set the probe to touch and the flip it to the other side the gap will be twice the error. -Brian Mea Culpa! You are certainly right, Brian. The difference at the probe is 3.7mm, this is what I have been incorrrectly calling the "offset", when in reality the offset is half of this or 1.85mm. I'm now wondering: much ado about nothing? |
#23
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
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#24
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Mar 13, 1:49*pm, wrote:
On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff wrote: On Mar 13, 10:16*am, wrote: On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff wrote: On Mar 12, 5:46*pm, jim beam wrote: Jeff wrote: On Mar 12, 2:47 pm, wrote: On Mar 12, 5:38 pm, Jeff wrote: I just bought a new carbon road bike frame, and when I measured the rear triangle, I found it offset 6mm to the left. [snip] the wheel is centered because of spacers on the axle ? how did you measure to determine the offset ? care to name the manufacturer of the frame ? I used the rear wheel from my current road bike. *The rear spacing on the carbon frame is correct (130mm) so the wheel goes right in and is centered left/right in the triangle. *Looks to me like the whole rear tirangle was laid up wrong (jigging error) at the factory... I measured the offset using a Park frame jig that grabs the frame at the BB and has an adjustable "slider" arm (similar to the one on the Park rear derailleur hanger tool) that you can adjust to pick up the desired part of the frame. *The you reverse the frame (without changing the slider arm setting) and pick up the same point on the other side of the frame. *This is a nice heavy-duty stand that makes coldsetting steel frames as easy as that operation can get. *(I'm not sure Park makes that stand any longer -- couldn't find it on their website.) if it's the tool i think it is, are you measuring to the outside or the inside of the drops? *if you're measuring to the outside, you can easily measure a difference, yet the frame is perfectly straight. *different thickness drops, etc. *what matters is that the two wheels are centered wrt each other, and that's measured on the *inside* of the drops. I guess I could take my current steel frame and introduce a similar 6mm misalignment to see if I can feel the offset when I ride it, but I was hoping that someone would say "Nah, you won't feel it" or "Yeah, it will be unrideable" to save me the work and mental anguish of coldsetting an error into a perfectly good frame... fwiw, i've seen frames with different thickness rear drops set "centered" for their outside, not their inside, and thus they were off-center. *apparently it's a simple mistake to make. and yes, it does make a difference to ride. Thank you for pointing that out -- I'll measure the dropout thickness this evening. *The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. *I still think that is a lot... Dear Jeff, What's the alignment on your current bike on the same Park jig? Cheers, Carl Fogel Hello Carl! When I built my current steel bike, I cold set it on the same jig for equal measurments on each dropout. *I built it with Campy dropouts which are the same thickness on the left and right... *That was some years ago, but I haven't crashed the bike (or backed into it with a car!) so I assume it is still square. Dear Jeff, Sounds reasonable to me. I see some vague concerns in this thread, but I can't help wondering if anyone can detect a 3.7 mm axle offset by just riding the bicycle. Apart from the natural wish to have the damn thing dead center, since it's brand-new, what would a 3.7 mm offset actually do, assuming that the wheel spins and the pedals turn without hitting the frame? Make the bike pull to one side? If so, which side? Increase rolling resistance? Make it more prone to shimmy? I'm not arguing, just wondering what the specific expectations are. Cheers, Carl Fogel- Hide quoted text - - Show quoted text - I think you've summarized the crux of the matter, Carl. Will I feel the difference or not? I'm not a club racer, but I do like to hammer on the downhills (usually to catch the group that dropped me on the climb!), and I *did* notice a marked difference in the fast downhill handling of my steel (Columbus SL) bike when I switched out the Columbus fork for an Easton aluminum. My point here is that I'm not totally numb, and I'm guessing that any handling quirks caused by the offset would be most apparent at high speed, where I like to ride. If it is a "No harm, no foul" situation, then it wouldn't bother me that the triangle was offset. In fact, you can't really see the offset with the "naked eye" because the rear wheel is centered correctly in the triangle, and if the handling/tire wear/whatever is not adversely effected by the offset, over time I'd probably forget that it was there. The 60's will do that to ya'... |
#25
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Mar 13, 5:49*pm, wrote:
On Fri, 13 Mar 2009 11:25:01 -0700 (PDT), Jeff wrote: On Mar 13, 10:16*am, wrote: On Fri, 13 Mar 2009 10:10:11 -0700 (PDT), Jeff wrote: On Mar 12, 5:46*pm, jim beam wrote: Jeff wrote: On Mar 12, 2:47 pm, wrote: On Mar 12, 5:38 pm, Jeff wrote: I just bought a new carbon road bike frame, and when I measured the rear triangle, I found it offset 6mm to the left. [snip] the wheel is centered because of spacers on the axle ? how did you measure to determine the offset ? care to name the manufacturer of the frame ? I used the rear wheel from my current road bike. *The rear spacing on the carbon frame is correct (130mm) so the wheel goes right in and is centered left/right in the triangle. *Looks to me like the whole rear tirangle was laid up wrong (jigging error) at the factory... I measured the offset using a Park frame jig that grabs the frame at the BB and has an adjustable "slider" arm (similar to the one on the Park rear derailleur hanger tool) that you can adjust to pick up the desired part of the frame. *The you reverse the frame (without changing the slider arm setting) and pick up the same point on the other side of the frame. *This is a nice heavy-duty stand that makes coldsetting steel frames as easy as that operation can get. *(I'm not sure Park makes that stand any longer -- couldn't find it on their website.) if it's the tool i think it is, are you measuring to the outside or the inside of the drops? *if you're measuring to the outside, you can easily measure a difference, yet the frame is perfectly straight. *different thickness drops, etc. *what matters is that the two wheels are centered wrt each other, and that's measured on the *inside* of the drops. I guess I could take my current steel frame and introduce a similar 6mm misalignment to see if I can feel the offset when I ride it, but I was hoping that someone would say "Nah, you won't feel it" or "Yeah, it will be unrideable" to save me the work and mental anguish of coldsetting an error into a perfectly good frame... fwiw, i've seen frames with different thickness rear drops set "centered" for their outside, not their inside, and thus they were off-center. *apparently it's a simple mistake to make. and yes, it does make a difference to ride. Thank you for pointing that out -- I'll measure the dropout thickness this evening. *The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. *I still think that is a lot... Dear Jeff, What's the alignment on your current bike on the same Park jig? Cheers, Carl Fogel Hello Carl! When I built my current steel bike, I cold set it on the same jig for equal measurments on each dropout. *I built it with Campy dropouts which are the same thickness on the left and right... *That was some years ago, but I haven't crashed the bike (or backed into it with a car!) so I assume it is still square. Dear Jeff, Sounds reasonable to me. I see some vague concerns in this thread, but I can't help wondering if anyone can detect a 3.7 mm axle offset by just riding the bicycle. Apart from the natural wish to have the damn thing dead center, since it's brand-new, what would a 3.7 mm offset actually do, assuming that the wheel spins and the pedals turn without hitting the frame? Make the bike pull to one side? If so, which side? Increase rolling resistance? Make it more prone to shimmy? I'm not arguing, just wondering what the specific expectations are. Cheers, Carl Fogel- Hide quoted text - - Show quoted text - I think you might find your rear wheel more prone to sliding out when leaning into a hard corner- I'm not sure, it was a long time ago and my early wheel builds using a manure truing stand ( centred in the stand but visbly off in the frame), so it could be something else. |
#26
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Mar 13, 6:08*pm, Jeff wrote:
On Mar 13, 1:29*pm, " wrote: Thank you for pointing that out -- I'll measure the dropout thickness this evening. *The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. *I still think that is a lot... Note that it would very easy to be measuring _twice_ the alignment error. If you set the probe to touch and the flip it to the other side the gap will be twice the error. -Brian Mea Culpa! You are certainly right, Brian. *The difference at the probe is 3.7mm, this is what I have been incorrrectly calling the "offset", when in reality the offset is half of this or 1.85mm. *I'm now wondering: much ado about nothing? 2 mm is nothing unless you are going for the hour perhaps. |
#27
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
On Mar 13, 4:34*pm, Jeff wrote:
Will I feel the difference or not? I should think so, but I am amazed at what people have not noticed about their bikes in the past. Chainline, and crank clearance are obvious concerns, but how the bike will track when you sit up to ride hands free is another. You will likely have to cock your body off to the side to get it to track straight, which gets old. If it is new, I would get it replaced. No reason to have a new product which was build wrong be your problem. Demand better from the maker. Chris |
#28
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
Jeff wrote:
On Mar 13, 1:29�pm, " wrote: Thank you for pointing that out -- I'll measure the dropout thickness this evening. �The "6mm" figure I stated was an eyeball; last evening I actually measured the offset and it is 3.7mm. �I still think that is a lot... Note that it would very easy to be measuring _twice_ the alignment error. If you set the probe to touch and the flip it to the other side the gap will be twice the error. -Brian Mea Culpa! You are certainly right, Brian. The difference at the probe is 3.7mm, this is what I have been incorrrectly calling the "offset", when in reality the offset is half of this or 1.85mm. I'm now wondering: much ado about nothing? sounds increasingly likely. what make is the frame? |
#29
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Rear Triangle Alignment -- Will 6mm make a difference I can feel?
Just bought a used 1978 Trek 531 frame that had been spread to fit a
10 speed by just settng the drive side. Of course it was out of alignment and it was interesting how it felt as I worked on it. Original setup rode fine as long as my hands were on the bars. No handed it pulled to the left dramatically. Using the sting around head tube method, I set both sides of the triangle roughly and tried it again. There was a great improvement, but it still pulled to the left.. Another run at it with more care and now it rides pretty straight. Not perfect but the string method is not as accurate as your setup. Wayne |
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