New steel Fork ,wheel sits off center ,what tolerance acceptable?

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Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 3 Jan 2021, 10:08am

531colin wrote:... the threaded end of the thru' axle is the end where the brake isn't.....why would you do that?...


it is a bit of a mystery. Why would you put the lever right next to the stinking hot brake disc anyway? Not much of it makes sense, does it...?

cheers
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531colin
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby 531colin » 3 Jan 2021, 10:13am

The whole concept eludes me, really. I just looked back at the Surly site and they don't even use a forward-facing slot for the "other" dropout, its a downward facing effort. Its not difficult at all to just turn the damned thing round?

Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 3 Jan 2021, 10:42am

possibly it is then more awkward to fettle it to make the alignment correct?

Other than that I can't think of a good reason. Two steps forward, at least one back again...? :shock:

cheers
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jimneycricket
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby jimneycricket » 3 Jan 2021, 3:33pm

Some interesting posts for the layman to read,

So maybe this design is flawed enough that it makes it too difficult to manufacture a very balanced out fork? Maybe all replacements would have similar variances in the tolerance or maybe my fork is the outlier? I will go back to the dealer and see what they think. Surly promote this design as making it easier to remove the wheel , which it is, but maybe at a cost.

Seeing that its a 2mm difference to the side of the fork from the rim on one side the wheel really is only off 1mm from center as it borrows 1mm from the other side if you follow. I don't like to be too pedantic about this stuff and I can kind of fix it in the center by moving the wheel around in the open dropout but I had hoped that a brand new frame with a good rep wouldn't need such compromises.

pwa
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby pwa » 3 Jan 2021, 3:38pm

jimneycricket wrote:Some interesting posts for the layman to read,

So maybe this design is flawed enough that it makes it too difficult to manufacture a very balanced out fork? Maybe all replacements would have similar variances in the tolerance or maybe my fork is the outlier? I will go back to the dealer and see what they think. Surly promote this design as making it easier to remove the wheel , which it is, but maybe at a cost.

Seeing that its a 2mm difference to the side of the fork from the rim on one side the wheel really is only off 1mm from center as it borrows 1mm from the other side if you follow. I don't like to be too pedantic about this stuff and I can kind of fix it in the center by moving the wheel around in the open dropout but I had hoped that a brand new frame with a good rep wouldn't need such compromises.

If you centred the rim by adjusting spoke tension, would the rim be moving toward the disc side or away from it? If away from it, there could be a tiny advantage to that, with slightly better spoke tension overall.

Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 3 Jan 2021, 3:51pm

as someone commented upthread, centring the rim between the fork blades will result in the contact patch of the tyre on the road being even more off centre than it was before, which would be counterproductive in terms of steering. Meanwhile getting the contact patch in the right place on the road will require the tyre to be even more off-centre in the forks than it is at present, which always looks obviously wrong, even if the bike steers OK.

cheers
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jimneycricket
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby jimneycricket » 3 Jan 2021, 6:00pm

Brucey wrote:as someone commented upthread, centring the rim between the fork blades will result in the contact patch of the tyre on the road being even more off centre than it was before, which would be counterproductive in terms of steering. Meanwhile getting the contact patch in the right place on the road will require the tyre to be even more off-centre in the forks than it is at present, which always looks obviously wrong, even if the bike steers OK.

cheers



So if I read this correctly then I shouldn't play with the wheel dish to center the wheel but moving the axle about in the dropout to center the wheel is still ok? or should I do neither and just let is sit where it sits in the dropouts even though off center

Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 3 Jan 2021, 6:49pm

if it were mine I'd send it back if possible.

If I couldn't do that I'd fix it by adding a blob of weld to dropout or by using a packing shim around the TA on the LH side.

cheers
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Cyril Haearn
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Cyril Haearn » 3 Jan 2021, 7:49pm

Looks wrong, minusplus? If it is visibly wrong, I think it must be wrong
Or could one just juggle washers on either side?
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reohn2
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby reohn2 » 3 Jan 2021, 11:10pm

There's a tolerance with anything mechanical, <2mm is IMHO within tolerance.
Were it mine I wouldn't bat an eye about it.
As I posted before,if it bothers the OP that much redish the wheel and after a week riding it he'll forget he ever had a problem.
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bgnukem
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby bgnukem » 4 Jan 2021, 8:04pm

Also wouldn't worry. I've been riding with incorrectly dished wheels offset by 5mm or more to one side and not noticed any dodgy handling issues.

2mm almost certainly within reasonable tolerances for a frameset. We're not dealing with a high precision product here......

Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 4 Jan 2021, 8:28pm

by contrast I'd expect better in a new frame. If a new frame doesn't come right it can be made right in most cases. However other designs allow the alignment to be adjusted and this one basically doesn't.

I'd expect a bike with this sort of alignment issue to ride OK-ish hands on, but need to be tipped one way to ride in a straight line no-hands. It may also shimmy more easily than it should do.

I've owned a lot of bikes and a few of them have been a bit like this when I got them, and in pretty much every case I have managed to resolve the issue and make the bike better to ride. However asides from the suggestions I have already made, a fault of this type with this fork design is pretty intractable.

If you want to simulate the fault on an extant bike (with similar trail) simply offset the front wheel in the dropouts, go for a ride, and see what it is like.

cheers
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reohn2
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby reohn2 » 4 Jan 2021, 10:53pm

Brucey wrote: .....If you want to simulate the fault on an extant bike (with similar trail) simply offset the front wheel in the dropouts, go for a ride, and see what it is like.

cheers

99.9%of cyclists wil feel no difference,the one's that do would feel a pea undeneath a 30cm thick mattress when they lie on it.
Just a reminder,we are discussing a sub 2mm out of track fork
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Brucey
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Brucey » 5 Jan 2021, 12:51am

reohn2 wrote:Just a reminder,we are discussing a sub 2mm out of track fork


that is the sort of size of error that needs correction, and that good framebuilders don't let out of their workshop.

I have taken frames that are bent like a dog's hind leg and they have not been right until they are right, and when they are right they are better aligned than that.

cheers
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Valbrona
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Re: New steel Fork ,wheel sits off center ,what tolerance acceptable?

Postby Valbrona » 5 Jan 2021, 5:40am

Brucey wrote:
reohn2 wrote:Just a reminder,we are discussing a sub 2mm out of track fork


that is the sort of size of error that needs correction, and that good framebuilders don't let out of their workshop.


Dropout alignment gauges can be used to align regular/QR dropouts, but they must also have a way of aligning TA fork/frame ends. Maybe they are faced as opposed to aligned?
I should coco.