Author Topic: front wheel offset in forks  (Read 5007 times)

Offline Jules

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front wheel offset in forks
« on: 27.05. 2011 09:20 »
Me again, I've assembled the front wheel into the forks so that I can check frame/rear wheel/front wheel alignment and note that the front wheel is closer to the RHS fork than the LHS fork ie not central. The bike is a 1956 A10 with full width hub and a spindle clamp on the LH fork ie spindle passes right through to a nut on the RH fork and is then clamped in position by the LH fork. The spacer seems to have the right protrusion that locates into the RH fork but it means that the brake hub is basically right up against the fork (whereas the rear has a spacer) - no spacer is shown anywhere in the books and the hole for the tommy bar is in about the right location relative to the left fork, so I can only assume its correct, but it looks wrong  *conf*.
Does anybody have any practical experience of this please? cheers
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Online muskrat

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Re: front wheel offset in forks
« Reply #1 on: 27.05. 2011 14:50 »
G'day Jules,
               first make sure the forks are straight and parallel. Easier to do this with the sliders off. Fit the wheel and tighten the nut. Now pump the suspension a few times then tighten the clamp. The rim should be central in the forks. If not spoke adjustment will be made to do so.
 I have checked mine to be true but the hole is partially covered. I can't remember how close the brake plate is to the slider, will look in the morning.
Cheers
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Online bsa-bill

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Re: front wheel offset in forks
« Reply #2 on: 27.05. 2011 16:29 »
Yes and if you have to move it across (the rim) it takes very little on each spoke, a half turn slack off  each spoke on the nearest side and a half turn tighter on the furthest side moves the rim probably as much as you need, now how do I know this *whistle*
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Re: front wheel offset in forks
« Reply #3 on: 28.05. 2011 23:49 »
G'day Jules,
                brake plate against slider. A few pics.
Cheers.
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Offline Jules

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Re: front wheel offset in forks
« Reply #4 on: 29.05. 2011 09:12 »
thanks Muskrat, I must say that it does look like mine, but then why would the wheel be laced up offset, seems very strange... I've attached some pictures too. It looks like I need to move the wheel across to the left about 10mm, I guess I could just add a spacer to the RHS? Would be interested in your (further) thoughts, if you have any, cheers
PS also started another thread because I've found that I have one leading and one trailing fork leg ie the two legs are angled forward at different angles   *sad2*.....
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Re: front wheel offset in forks
« Reply #5 on: 29.05. 2011 20:36 »
G'day Jules,
                looks like the PO didn't measure the hub to rim offset before they unlaced it and didn;t bother to correct it. I don't like the spacer idea and may create other problems. If the gap is 10mm larger on one side the rim needs to move 5mm. 1 1/2 to 2 turns on each nipple should get you close (give them a good dose of WD the night before), and might get away with not removing the ryre just let the wind out. BUT there is a chance a spoke could puncture the tube.
If I understand your other ? right it means either the triple clamps or fork legs are bent.
I like the short seal holders. Do you have internal springs?
Cheers
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Offline Jules

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Re: front wheel offset in forks
« Reply #6 on: 30.05. 2011 07:36 »
Hi Muskrat, thanks for the feedback and sorry to disappoint you but the short seal holders were the work of the butcher who had the bike years ago. He hacksawed off the shrouds (presumably because they were rubbing through due to the bent legs) left the springs exposed and chromed everything, then proceeded to bush bash the bike and totalled the forks (and I mean totalled them !). I have replaced the legs and fitted new bushes and hard chromed the legs, they slide very nicely now but have reassembled them using the old seals and yoke bearings just to see if I need to get other parts like shrouds and things sorted/painted before I do the final assembly to avoid damaging the new parts......any other thoughts welcome (like where's the best place to get some shrouds, I thought I had found some but they appear to be RR ilo Flash), cheers
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Offline Angus

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Re: front wheel offset in forks
« Reply #7 on: 19.01. 2014 21:21 »
Hope its Ok to reopen this thread, think I have a similar problem.
1960 A7 with full width hubs and groove in axle and bottom clamps to hold front wheel on.
Have run for 14 months with very old tyres (still soft and no cracks) but it was worrying me particularly as I still want to ride but it never really dries out.
Anyway it was fine. Bought new tyres same size, same manufacturer but different model (Avon AM20).
This tyre rubs on the mudguard right hand side when looking at the bike, the old tyre must have been close (unless I am missing something) but did not rub.
The wheels where rebuilt in the 1980’s with new rims and spokes but not used until rebuild Oct 1012, so I assume it can not be anything but the offset (about 15mm gap on right hand side).
I have check the A10 and that front wheel looks even in the forks.

Confirmation or other options would be good before I contact a wheel builder to look at it.
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Offline 1959superocket

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Re: front wheel offset in forks
« Reply #8 on: 19.01. 2014 21:57 »
I remember reading somewhere that the front wheel on a FWH 58-62 A10 does have an offset so should not be laced up central to hub.
I cannot remember what the offset is but BSA familiar wheelbuilders will know and I thought it was only about 5mm which might be to compensate for the nut that holds the brake plate?

Regards

Stuart


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Re: front wheel offset in forks
« Reply #9 on: 20.01. 2014 07:26 »
The rim should be central in the forks. That is assuming the triple clamps and stanchions are straight. The hub could be anywhere.
Cheers
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Online KiwiGF

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Re: front wheel offset in forks
« Reply #10 on: 20.01. 2014 09:20 »
 i have a 56 a10 with ariel hubs, just a little tip, make sure the left hand leg is not under any stress caused by being pulled over when the axle is pulled through. If the axle catches on the leg it can pull the leg to one side and cause the forks to jam or be very stiff. In one of your pics it looks like the leg might be actually too far to the left as the tommy bar hole is partially covered by the leg?

I agree with othe comments that the wheel seems to have been laced with incorrect offset, albeit I suspect there is little if any offset on the ariel hubs, the centre of the rim should sit in the middle of the 2 spoke flanges?
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Offline Angus

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Re: front wheel offset in forks
« Reply #11 on: 20.01. 2014 14:13 »
Thanks for the feedback.
The forks etc are all OK so must be the offset. I spoke to the friend who rebuilt them in the 1980’s and he remembers doing it and says he did not put any offset on either front or rear. He did offer to fix them but its not what he does anymore so I will take them to a wheel builder. I assume the rear needs an offset too difficult to see as the chainguard stops measuring against the swinging arm.
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Online terryg

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Re: front wheel offset in forks
« Reply #12 on: 20.01. 2014 15:03 »
Hello Angus - I'm in a similar situation to you but for different reasons.  My SR is in pieces and I have just laced the new rims and spokes but left them untensioned.  As the frame is apart for painting, my plan is to set the front wheel rim central in the forks (by adjusting any required offset) upon reassembly and then align the rear rim centreline with the front, by setting the necessary offset.  In my case, as both rims are WM2, checking alignment will be a little easier than with a wider rear.
Why didn't I measure offsets before removing the hubs?  Because the bike has an unknown history and going back to basics seemed a better option.
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Re: front wheel offset in forks
« Reply #13 on: 20.01. 2014 15:16 »
If the wheel is still true then it's an easy job to move it to centre of the forks.
Start at the valve and go right around the wheel slakening off the spokes on the side that too near the forks by only a quarter turn, starting at the valve again on the otherside tighten the spokes one quarter turn, (if you have to stop on either side mark the spoke you are upto (done) so you don't lose your place)
 check the wheel for centre, you might have to go around both sides again but it's amazing how much a quarter turn will move it  across.
Job satisfaction is good and if you manage to put it out of true "then" you can take it to a wheel biulder
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All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Jules

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Re: front wheel offset in forks
« Reply #14 on: 28.01. 2014 07:54 »
Hello all, I'm glad my earlier observation prompted some more discussion on this topic because since getting my headstock sorted this is one of my next jobs to do..... however, just a prompt for Terryg regarding aligning the wheels. I plan to do the same after setting up the front, then aligning the rear, but I noticed that my front and rear rims are actually slightly different overall widths due to a difference in how the rim has been rolled over (see my earlier post on this), hence I will need to take this into account with the alignment - worth a check Terryg?
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