|
|
|
|
#46
11-24-2016, 09:20 PM
|
|||
|
|||
|
In my opinion the most difficult part of building a frame is getting a rear wheel to center exactly. This is a fairly common and seldom checked precisely by owners. There are numerous things that can throw it off including that the dropouts are slightly shifted to one side. That may be fixable by bending them both back to being equidistant from the centerline. It is highly possible that one seat stay is slightly longer than the other. Very little difference at the dropout is magnified out by the rim by the ratio of axle width to rim radius. This means that 1mm of seat stay length difference can move a wheel over be almost 3mm.
What also gets me riled up is that really expensive jigs (costing in the neighborhood of $5000) doesn’t insure rear wheel accuracy either if the rear triangle is built in one. I’ve had a few in my shop I was not happy with. It is possible to get the length of both the chain stays and seat stays right with patience and a few simple tools. Almost every one of my frame building class students leave with a frame they made that will center a wheel. There are always a few students in which precision is just not part of there personality. If they can do it right on there 1st try than every professional frame builder should be able to too. Of course not every pro wants to make the effort or just trusts their jig. I’m kind of surprised this isn’t a more commonly identified problem. As I am also a frame painter that checks frames for alignment when they come in and I know many wheels are off by some small amount. Of course whether this makes a difference in the ride is a separate discussion. 
|
|
#47
11-24-2016, 09:32 PM
|
|||
|
|||
|
Quote:
|
|
#48
11-25-2016, 05:55 AM
|
||||
|
||||
|
Quote:
__________________
Chisholm's Custom Wheels Qui Si Parla Campagnolo
|
|
#49
11-25-2016, 08:10 AM
|
|||
|
|||
|
With international shipping and all the tarrifs the costs add up so quickly. If there are problems it makes it really costly to resolve. I remember a colnago I had in 1998 was 128mm spacing, and the chain would rub the frame in the 12-53 combo.
I really hope that I am able to have this frame straightened so that it is safe to ride. The paint looks nice and the size looks correct. Quote:
|
|
#50
11-25-2016, 08:29 AM
|
|||
|
|||
|
It has been said several times above. Just because the rear wheel is not centered in the seat stays.....does not mean it is not in alignment. Does not make it dangerous or a problem to ride. Most of us like to see things like this centered, me also....but it is probably just a sloppy build. The drive side seat stay has to curve out more to clear the cassette, and a good builder will allow for this and make the rear wheel centered in the stays. Have the alignment checked. You can probably center the rear wheel between the seat stays better using a file carefully.....but then you could mess up alignment....and make a loose fit in drop out.
Last edited by Ralph; 11-25-2016 at 08:34 AM.
|
|
#51
11-25-2016, 08:34 AM
|
|||
|
|||
|
Quote:
|
|
#52
11-25-2016, 10:29 AM
|
||||
|
||||
|
I've seen a few people wonder if the frame is actually out of alignment or if instead it is the result of a "sloppy build." As someone who has built a few frames I have trouble fully understanding how this would be done.
It certainly is possible to have a frame where the plane of the rear wheel is on the same plane as the frame centerline and at the same time have the c-stays or s-stays be off to one side. In other words the frame is functionally straight but looks to be off because the distance from the rim to the s-stays is different from side to side. I say this is possible but frankly it's very uncommon. If the frame "looks crooked but is really straight" it would typically come from the seat stays being mitered far off center and placed onto the seat tube off to one side. This can happen if the build is "sloppy" but it takes a stacking of mistakes....first the stays need to be improperly mitered off center - then the builder needs to mount the stays off center on the back of the seat tube - then the builder needs to disregard the reading from the jig telling him that area near the brake bridge is off center (most every jig I've ever used has an arm that holds the s-stays and provides a check to show they are equidistant from the center line) - then the builder needs to put the frame on the alignment plate and disregard the fact that the stays are off center and finally he needs to put the wheel into the frame and disregard the fact that the rear wheel is off center between the s-stays. At the same time it would be very difficult to attach the s-stays to the drops in some way that would result in the space between the rim and tube to be off by much. Due to the geometry involved the s-stay would need to be off to one side at the drop by 3-4 mm to end up with a 1 mm offset at the rim.....and the drops typically just aren't big enough to allow the stay to be placed on the drop that far off. Keep in mind that most road stays are 11-13 mm in diameter at the lower end so it's a lot of work to put the stay far off center on the drop....and it would be very obvious visually. Someone above noted that the drive-side s-stay is bent or offset in some way to allow room for the chain/cassette. I've personally never seen this but I suppose it's possible. Most any good dropout design eliminates any need to do this. So........is it possible that the frame is functionally straight but just looks crooked? Sure. Is it likely? No. For the builder it would be like winning the lotto to stumble into a frame that is straight but looks crooked. -------------- If I had this frame in my hands I would first check the BB shell facing and then put it on the plate. I would then check to see that the seat tube is parallel to the plate and on center. The next step (disregarding the front end of the frame) would be to check the inner drop faces to the plate to verify that they are equidistant from the frame centerline. Next I would check to see that the seat stays at the brake bridge are also right compared to the frame centerline. The frame would then be removed from the plate and the dropout alignment would be checked to be sure they are concentric and parallel. Finally the reference wheel would be placed in the frame and clamped in place to be sure that the rim is centered between the previously centered seat and chainstays. It would be presumptuous for me to say that the above is the one and only way to do a proper alignment but I doubt many experienced builders would argue with the basic procedure. One can only stray so far from the above and still hope to have a frame that rides straight and looks straight. To end up with the rim off center by some visual amount like the frame in question one would need to skip more than a few of the basic steps.........or they'd need to get more luckier than I've ever seen a builder get and have the frame come out functionally straight while looking crooked. If Zank gets his hands on the frame he'll be able to see what is amiss and determine if it can be put right at this point. Thanks for sticking with me through the long post - I just couldn't let the "sloppy build but straight" thing hang out there. Have a great day - I'm going to work just a bit an then take the fatbike out and ride some snow! dave
|
|
#54
11-25-2016, 12:04 PM
|
|||
|
|||
|
Dave, thanks for taking the time to post. I enjoy hearing about the process. OP, I hope you get things worked out. Judging from their email though it looks like they're telling you to pound sand. These guys just landed at the top of my do not buy list. I'm not sure what I'd do. I have a good friend who had a Taylor frame crack. Taylor said he'd fix it. Frame was sent back and never returned.
|
|
#55
11-25-2016, 12:12 PM
|
|||
|
|||
|
Quote:
also reaffirmed my belief that Zank rules (and also Kirk). just rode one of his bikes no handed on the rollers the other night, with no tracking issues whatsoever 
|
|
#56
11-25-2016, 12:20 PM
|
|||
|
|||
|
my money is on their fixture as the problem
The 1st thing to do is turn the wheel around and put it in the other way. Of course it should be offset from the stays the same amount. Besides seeing if the wheel is dished correctly (which has already been checked) this can also tell if for some reason the rear axle is a little bent (unlikely but it happens).
If I was to make a bet as to what is the most likely problem, I would put the most money on their fixture being slightly out. I believe this is more likely than them just being careless (which is also probable). Of course alignment can also be a culprit from either the build process or shipping. I am going to repeat myself that accurate fixturing is a fairly common problem even with expensive ones (especially with those that start with an initial at or near the front of the alphabet). I have had a number of different fixtures in my shop during the many years I have built frames and most of them (even the expensive ones) are off a little. One of the reasons I would guess the builders of this frame in our discussion were a bit put off by your questioning is that they wouldn’t know how to fix the problem if there is an error someplace in their equipment.
|
|
#57
11-25-2016, 03:47 PM
|
|||
|
|||
|
the fixture could be out, but it's quite possible to put misalignment in a frame while welding or brazing. Granted, they should be checking for that after the build
|
|
#58
11-25-2016, 05:24 PM
|
|||
|
|||
|
If you dont have a jig, what you do is to put the frame in the table several times while construction... before painting... and after painting aswell just before get the frame to its owner.
Honestly, if they cut corners in something as simple as check the frame in the table and check the dropouts after being painted then clearly it is a little bit of overconfidence from their part or that it is their modus operandi, if it is... well they just suck.
|
|
#60
11-25-2016, 07:25 PM
|
|||
|
|||
|
Depending on the model, the road bikes range from $2,400 to $3,700ish, also depending on exchange rates. This is really unfortunate—I've ridden Tim P's Jaegher and really liked the way it rode, and the finish is beautiful. I was tempted to get one, but after this and the earlier thread about the sloppy welds, not any more. Life's too short, and the list of quality builders stateside (of which Dave is at the top) is long.
|
 |
|
|
Linear Mode
