Bent frame
11-30-17 | 01:30 PM
#26
Senior Member
Joined: Nov 2010
Posts: 22,994
Likes: 10,496
From: Sacramento, CA
Bikes: old ones
The mechanic is coming to work tomorrow to take a look at the bike. I am curious/excited to hear what he has to say about it. I just want to get this damn thing to shift properly. I agree that the symptoms seem like a hanger, but I've had two people look at the hanger and they both agreed it was fine. The thing is, if the rear triangle is bent somewhat, wouldn't that cause similar symptoms to a bent hanger, since the rear end of the bike wouldn't be aligned with the middle.
And on that note, today I tried to ride my bike without my hands --- and i couldn't. It kept pulling to the drive train side. So maybe that reinforces a bent frame?
I'll take some photos of my bike and frame tomorrow and post them.
And on that note, today I tried to ride my bike without my hands --- and i couldn't. It kept pulling to the drive train side. So maybe that reinforces a bent frame?
I'll take some photos of my bike and frame tomorrow and post them.
The shifting depends on the positional relationship of the rear derailleur cage to the rear wheel cogs, so that's less likely to be solved by realigning the frame. But from your description it can't hurt to try it. Make sure the final step is to check and adjust the parallel alignment of the rear dropouts.
12-01-17 | 11:41 PM
#27
Thread Starter
Senior Member
Joined: Sep 2009
Posts: 396
Likes: 4
From: Vancouver, BC
Bikes: Jamis Aurora Elite, Jamis Citizen 3.0, Giant TCR Advanced 2
The mechanic came by on Thursday and tried to fix the frame for me, but it didn't work. He said something about how the drive side stay was out of position by 5 mm and he was able to get it back close to where it was supposed to be left to right, but that it was also off positionally in another dimension - up and down? forward or back? I'm not sure. That doesn't make a lot of sense to me, but I trust him because he has been super thorough the entire time. I didn't have time to chat with him about it cause i was in the middle of a meeting. He measured the frame for me before he started working on it and then again after, and it was clearly much better than it was before.
BUUUUT: the shifting is still not right. It's better, but not good yet.
When I try to ride without my hands on the handle bars, it's 'easier', but it still doesn't quite work. Before it was impossible to do it even for a fraction of a second - it would start pulling very quickly- now it doesn't seem to do it quite as fast - but it still does it. I confirmed that I can actually ride w/o hands by taking my road bike out for 15 minutes just to prove to myself that it's not a problem with me (and it's not).
So I don't know what to do. He suggested I take it to either a frame builder and ask them to take a look at it (chris dekerf lives pretty close) or take it to a bike shop that he knows has more experience bending bikes back into shape. I called the bike shop and they said they have done it on rare occasions before for old steel bikes that held a lot of sentimental value to someone, but they weren't really comfortable doing it in this case. They suggested I call a different bike shop and see what they say - but they did tell me that if I'm having these sorts of issues and it is frame related, it's probably a frame-builder problem to solve rather than a bike mechanic problem to solve.
I contacted Jamis and it turns out they have one frame left in the year my bike was made. They are going to figure out how much it's worth and email me a price on Monday,
BUUUUT: the shifting is still not right. It's better, but not good yet.
When I try to ride without my hands on the handle bars, it's 'easier', but it still doesn't quite work. Before it was impossible to do it even for a fraction of a second - it would start pulling very quickly- now it doesn't seem to do it quite as fast - but it still does it. I confirmed that I can actually ride w/o hands by taking my road bike out for 15 minutes just to prove to myself that it's not a problem with me (and it's not).
So I don't know what to do. He suggested I take it to either a frame builder and ask them to take a look at it (chris dekerf lives pretty close) or take it to a bike shop that he knows has more experience bending bikes back into shape. I called the bike shop and they said they have done it on rare occasions before for old steel bikes that held a lot of sentimental value to someone, but they weren't really comfortable doing it in this case. They suggested I call a different bike shop and see what they say - but they did tell me that if I'm having these sorts of issues and it is frame related, it's probably a frame-builder problem to solve rather than a bike mechanic problem to solve.
I contacted Jamis and it turns out they have one frame left in the year my bike was made. They are going to figure out how much it's worth and email me a price on Monday,
12-02-17 | 01:07 AM
#28
Grumpy Old Bugga
Joined: Oct 2006
Posts: 4,229
Likes: 9
From: Adelaide, AUSTRALIA
Bikes: Hillbrick, Malvern Star Oppy S2, Europa (R.I.P.)
My old Europa went the same way. In my case, a wrinkle had formed in the seat tube - it'd been there for years, so long I just considered it part of the bike. Over the years though, it had started to bend backwards, in the process bending the seat stays. It too was spotted when I took it in for shifting problems though in in my case, it was a bent hanger causing the problems.
If you've got a frame builder nearby, it's certainly worth getting them to have a look at it but get a feel for what it's worth to you first, repairs could get expensive.
It's not hard to straighten a frame, I've done it myself on the kitchen floor using care and Sheldon Brown's article. In the Europa's case, the bent seat tube was a deal breaker unfortunately - I bought that bike new in the 80s and she's been with me ever since.
If you've got a frame builder nearby, it's certainly worth getting them to have a look at it but get a feel for what it's worth to you first, repairs could get expensive.
It's not hard to straighten a frame, I've done it myself on the kitchen floor using care and Sheldon Brown's article. In the Europa's case, the bent seat tube was a deal breaker unfortunately - I bought that bike new in the 80s and she's been with me ever since.
12-03-17 | 12:52 AM
#29
Senior Member
Joined: Feb 2012
Posts: 19,349
Likes: 5,466
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Before I would bend a frame I would want to eliminate other issues like wheels out of dish or a fork that's out of line.
To help understand alignment try this- The wheels should be coplanar with each other and with the main frame. The steerer and seat tube should be parallel in the frame's plane. The string test only tells if the axle's mid point is centered WRT the main frame. The wheel can be cocked one way or another but still have the axle centered to the main frame. Think of it as having one chain or seat stay longer then it's mate. The drop outs will be the right width apart and centered to the main frame but the rim/tire will be off plane. So too with the fork. The drop outs should be centered WRT the steerer's axis. Both blades should be the same length. But the axle and crown don't need to be parallel, it just looks better that way
.
This alignment is what some will call the handling one. The way the bike steers/tracks consistently evenly side to side. But there's another aspect of alignment, the biomechanical one.
This second category of alignment is how the body is positioned on the bike, how one's movements are centered WRT the bike. So a BB that's crooked will result in one's legs pedaling in circles that are off plane to the bike. A saddle that's been whacked to one side will set the hips off center. Bars not centered or that are bent will cock shoulders.
A motivated builder can measure/assess all these factors and come back with much more info then most shop wrenches. What this info ends up meaning to any one rider... Andy
When many shop wrenches look at a frame's alignment they often don't have a handle on all the aspects affecting the handling or the
To help understand alignment try this- The wheels should be coplanar with each other and with the main frame. The steerer and seat tube should be parallel in the frame's plane. The string test only tells if the axle's mid point is centered WRT the main frame. The wheel can be cocked one way or another but still have the axle centered to the main frame. Think of it as having one chain or seat stay longer then it's mate. The drop outs will be the right width apart and centered to the main frame but the rim/tire will be off plane. So too with the fork. The drop outs should be centered WRT the steerer's axis. Both blades should be the same length. But the axle and crown don't need to be parallel, it just looks better that way
. This alignment is what some will call the handling one. The way the bike steers/tracks consistently evenly side to side. But there's another aspect of alignment, the biomechanical one.
This second category of alignment is how the body is positioned on the bike, how one's movements are centered WRT the bike. So a BB that's crooked will result in one's legs pedaling in circles that are off plane to the bike. A saddle that's been whacked to one side will set the hips off center. Bars not centered or that are bent will cock shoulders.
A motivated builder can measure/assess all these factors and come back with much more info then most shop wrenches. What this info ends up meaning to any one rider... Andy
When many shop wrenches look at a frame's alignment they often don't have a handle on all the aspects affecting the handling or the
12-03-17 | 08:25 PM
#30
Thread Starter
Senior Member
Joined: Sep 2009
Posts: 396
Likes: 4
From: Vancouver, BC
Bikes: Jamis Aurora Elite, Jamis Citizen 3.0, Giant TCR Advanced 2
Hi Andrew,
Thank you very much for taking the time to give me such a thoughtful and considered reply. I really appreciate your help, and the time everyone in this thread has taken to give me their help. I try appreciate it all.
I have a few follow up questions. First of all, what would I do to check of the wheel is out of dish. Is that something I would need to take the bike to a frame builder to check or should a good mechanic be able to help me out with that. I have a similar question about the fork being out of line. I'm not even sure what that means?
I can understand how the wheel being out of dish could affect shifting, but I don't understand how that can't be corrected by aligning the derailleur, or why it would affect the quality of shifting differentially depending on the relative position on the cog, that would strike me as a problem caused by being out of parallel with each other rather than being slightly out of plane. I hope this doesn't seem like I'm being difficult, I'm just trying to understand.
Second, how would the fork alignment affect shifting? How does the front end of the bike affect the shifting on the rear derailleur? Again, I'm not trying to be argumentative- I just want to understand. All of this seems like good news to me because it makes me think I can possibly keep this frame without too much difficulty.
The biomechanical stuff is interesting, but I am really confused about how that would affect shifting. Or were you speaking to the issue of being able to balance?
Do you have any suggestions for me for things I should do and/or say to a mechanic? Incidentally I am going to a bike store tomorrow in Vancouver to test ride a few bikes out (as a way of testing out their frames). It's a bike shop that does mostly custom frame build outs, so I could always ask that guy to take a look too.
Thanks so much,
Brad
Thank you very much for taking the time to give me such a thoughtful and considered reply. I really appreciate your help, and the time everyone in this thread has taken to give me their help. I try appreciate it all.
I have a few follow up questions. First of all, what would I do to check of the wheel is out of dish. Is that something I would need to take the bike to a frame builder to check or should a good mechanic be able to help me out with that. I have a similar question about the fork being out of line. I'm not even sure what that means?
I can understand how the wheel being out of dish could affect shifting, but I don't understand how that can't be corrected by aligning the derailleur, or why it would affect the quality of shifting differentially depending on the relative position on the cog, that would strike me as a problem caused by being out of parallel with each other rather than being slightly out of plane. I hope this doesn't seem like I'm being difficult, I'm just trying to understand.
Second, how would the fork alignment affect shifting? How does the front end of the bike affect the shifting on the rear derailleur? Again, I'm not trying to be argumentative- I just want to understand. All of this seems like good news to me because it makes me think I can possibly keep this frame without too much difficulty.
The biomechanical stuff is interesting, but I am really confused about how that would affect shifting. Or were you speaking to the issue of being able to balance?
Do you have any suggestions for me for things I should do and/or say to a mechanic? Incidentally I am going to a bike store tomorrow in Vancouver to test ride a few bikes out (as a way of testing out their frames). It's a bike shop that does mostly custom frame build outs, so I could always ask that guy to take a look too.
Thanks so much,
Brad
Before I would bend a frame I would want to eliminate other issues like wheels out of dish or a fork that's out of line.
To help understand alignment try this- The wheels should be coplanar with each other and with the main frame. The steerer and seat tube should be parallel in the frame's plane. The string test only tells if the axle's mid point is centered WRT the main frame. The wheel can be cocked one way or another but still have the axle centered to the main frame. Think of it as having one chain or seat stay longer then it's mate. The drop outs will be the right width apart and centered to the main frame but the rim/tire will be off plane. So too with the fork. The drop outs should be centered WRT the steerer's axis. Both blades should be the same length. But the axle and crown don't need to be parallel, it just looks better that way.
This alignment is what some will call the handling one. The way the bike steers/tracks consistently evenly side to side. But there's another aspect of alignment, the biomechanical one.
This second category of alignment is how the body is positioned on the bike, how one's movements are centered WRT the bike. So a BB that's crooked will result in one's legs pedaling in circles that are off plane to the bike. A saddle that's been whacked to one side will set the hips off center. Bars not centered or that are bent will cock shoulders.
A motivated builder can measure/assess all these factors and come back with much more info then most shop wrenches. What this info ends up meaning to any one rider... Andy
When many shop wrenches look at a frame's alignment they often don't have a handle on all the aspects affecting the handling or the
To help understand alignment try this- The wheels should be coplanar with each other and with the main frame. The steerer and seat tube should be parallel in the frame's plane. The string test only tells if the axle's mid point is centered WRT the main frame. The wheel can be cocked one way or another but still have the axle centered to the main frame. Think of it as having one chain or seat stay longer then it's mate. The drop outs will be the right width apart and centered to the main frame but the rim/tire will be off plane. So too with the fork. The drop outs should be centered WRT the steerer's axis. Both blades should be the same length. But the axle and crown don't need to be parallel, it just looks better that way
. This alignment is what some will call the handling one. The way the bike steers/tracks consistently evenly side to side. But there's another aspect of alignment, the biomechanical one.
This second category of alignment is how the body is positioned on the bike, how one's movements are centered WRT the bike. So a BB that's crooked will result in one's legs pedaling in circles that are off plane to the bike. A saddle that's been whacked to one side will set the hips off center. Bars not centered or that are bent will cock shoulders.
A motivated builder can measure/assess all these factors and come back with much more info then most shop wrenches. What this info ends up meaning to any one rider... Andy
When many shop wrenches look at a frame's alignment they often don't have a handle on all the aspects affecting the handling or the
12-03-17 | 09:05 PM
#31
Senior Member
Joined: Feb 2012
Posts: 19,349
Likes: 5,466
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Hi Andrew,
Thank you very much for taking the time to give me such a thoughtful and considered reply. I really appreciate your help, and the time everyone in this thread has taken to give me their help. I try appreciate it all.
I have a few follow up questions. First of all, what would I do to check of the wheel is out of dish. Is that something I would need to take the bike to a frame builder to check or should a good mechanic be able to help me out with that. I have a similar question about the fork being out of line. I'm not even sure what that means?
Dish is the term given to having the rim centered between the axle lock nut ends. For a disk or cogged wheel where the flanges are not equal distant from the axle's center point this means that one side's spokes will have a steeper angle between the rim and flange. This is very easy to check w/o any fancy tools. A flat bench top or counter with four stacks of the same coins is your tool. Three stacks of the same heights are positioned so when the wheel is laid on them, with the rim sitting on the stacks, the wheel/rim is basically parallel to the surface. The fourth stack will be less high and only tall enough to reach from the surface to the close axle end cap/lock nut. Flip the wheel over. If the rim is centered WRT the axle end caps/lock nuts then all four points will match up as before. Of course the wheel needs to be fairly true to start with. If the axle end caps don't sit on that fourth stack the same way with each flip of the wheel then the rim is off center, the wheel is out of dish. Professional dishing tools mimic this across the rim and reach in toward the axle end caps but with an adjustable axle end cap pointer. Repeat this a few times to insure no errors.
I can understand how the wheel being out of dish could affect shifting, but I don't understand how that can't be corrected by aligning the derailleur, or why it would affect the quality of shifting differentially depending on the relative position on the cog, that would strike me as a problem caused by being out of parallel with each other rather than being slightly out of plane. I hope this doesn't seem like I'm being difficult, I'm just trying to understand.
The miss alignment that a hanger bend (or twisted der/cage) is generally far greater an offness then a wheel's slight cockedness when in a frame. So a wheel that sits a bit off usually won't effect the shifting much. Besides the datum that any hanger alignment is done WRT is the rim (or the hub with the Shimano tools. Still the hub and rim are "solid" to each other). So an aligned hanger will negate/correct for a cocked in frame wheel.
Second, how would the fork alignment affect shifting? How does the front end of the bike affect the shifting on the rear derailleur? Again, I'm not trying to be argumentative- I just want to understand. All of this seems like good news to me because it makes me think I can possibly keep this frame without too much difficulty.
The fork alignment shouldn't effect shifting at all. But the mention of riding no hands being hard and the bike tending to steer off the straight and a fork that's off will contribute to handling issues. I am adding more then one issue's possible causes.
The biomechanical stuff is interesting, but I am really confused about how that would affect shifting. Or were you speaking to the issue of being able to balance?
Again this won't affect shifting. But more description of the full aspects of alignment that many don't bother to talk about but still are part of a straight bike.
Do you have any suggestions for me for things I should do and/or say to a mechanic? Incidentally I am going to a bike store tomorrow in Vancouver to test ride a few bikes out (as a way of testing out their frames). It's a bike shop that does mostly custom frame build outs, so I could always ask that guy to take a look too.
Thanks so much,
Brad
Thank you very much for taking the time to give me such a thoughtful and considered reply. I really appreciate your help, and the time everyone in this thread has taken to give me their help. I try appreciate it all.
I have a few follow up questions. First of all, what would I do to check of the wheel is out of dish. Is that something I would need to take the bike to a frame builder to check or should a good mechanic be able to help me out with that. I have a similar question about the fork being out of line. I'm not even sure what that means?
Dish is the term given to having the rim centered between the axle lock nut ends. For a disk or cogged wheel where the flanges are not equal distant from the axle's center point this means that one side's spokes will have a steeper angle between the rim and flange. This is very easy to check w/o any fancy tools. A flat bench top or counter with four stacks of the same coins is your tool. Three stacks of the same heights are positioned so when the wheel is laid on them, with the rim sitting on the stacks, the wheel/rim is basically parallel to the surface. The fourth stack will be less high and only tall enough to reach from the surface to the close axle end cap/lock nut. Flip the wheel over. If the rim is centered WRT the axle end caps/lock nuts then all four points will match up as before. Of course the wheel needs to be fairly true to start with. If the axle end caps don't sit on that fourth stack the same way with each flip of the wheel then the rim is off center, the wheel is out of dish. Professional dishing tools mimic this across the rim and reach in toward the axle end caps but with an adjustable axle end cap pointer. Repeat this a few times to insure no errors.
I can understand how the wheel being out of dish could affect shifting, but I don't understand how that can't be corrected by aligning the derailleur, or why it would affect the quality of shifting differentially depending on the relative position on the cog, that would strike me as a problem caused by being out of parallel with each other rather than being slightly out of plane. I hope this doesn't seem like I'm being difficult, I'm just trying to understand.
The miss alignment that a hanger bend (or twisted der/cage) is generally far greater an offness then a wheel's slight cockedness when in a frame. So a wheel that sits a bit off usually won't effect the shifting much. Besides the datum that any hanger alignment is done WRT is the rim (or the hub with the Shimano tools. Still the hub and rim are "solid" to each other). So an aligned hanger will negate/correct for a cocked in frame wheel.
Second, how would the fork alignment affect shifting? How does the front end of the bike affect the shifting on the rear derailleur? Again, I'm not trying to be argumentative- I just want to understand. All of this seems like good news to me because it makes me think I can possibly keep this frame without too much difficulty.
The fork alignment shouldn't effect shifting at all. But the mention of riding no hands being hard and the bike tending to steer off the straight and a fork that's off will contribute to handling issues. I am adding more then one issue's possible causes.
The biomechanical stuff is interesting, but I am really confused about how that would affect shifting. Or were you speaking to the issue of being able to balance?
Again this won't affect shifting. But more description of the full aspects of alignment that many don't bother to talk about but still are part of a straight bike.
Do you have any suggestions for me for things I should do and/or say to a mechanic? Incidentally I am going to a bike store tomorrow in Vancouver to test ride a few bikes out (as a way of testing out their frames). It's a bike shop that does mostly custom frame build outs, so I could always ask that guy to take a look too.
Thanks so much,
Brad
Here are a couple of links to previous threads I've posted to involving alignment, checking such and related stuff. I hope this gives you a greater understanding as to the issues affecting alignment and how we control or look for them. Andy
Front wheel turns hard right.
Frame Aligning Discussion
