Author Topic: 1955 b31 wheel offsets  (Read 191 times)

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mashermick

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1955 b31 wheel offsets
« on: 16 May, 2022, 21:04:33 »
I have a 54 s/arm b31 ,fitting new rims and tyres I found the front wouldn't lace up right,and the 3.25 wouldn't sit right on awm2 rim,the spokes had a slight bow at the nipple ,referred to the photos taken and sure laced as the original one(centre punched  hole 1 so I started in the right placed, weird.a y thoughts would be welcome.  Am going to fit a wm3 to ee if the tyre fits better ( new Avon )  thanks

spaceman

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Re: 1955 b31 wheel offsets
« Reply #1 on: 17 May, 2022, 06:11:18 »
If I understand you correctly, the nipples are not in line with the spokes causing a slight bow? At face value, this would mean that the holes cut in the rim for the nipples are not at the correct angles?

Obviously, you are reliant on the rim supplier to have cut the angles correctly for the front hub you have. You didn't say which type of hub this is but I assume that it is a single sided in which case the spokes on either side are of different lengths?

The classic mistake in rebuilding this type of hub is to get the rim the wrong way round since the nipple hole angles are slightly different for the left and right sets of spokes - that is for the long and short sets of spokes. If the rim has been fitted the correct way round, it is possible to lace up the wheel wrongly but this would take some doing and would be fairly obviously wrong.

If neither of these two possibilities are the case, this would only leave the nipple hole angles not being correct for your hub. If you think this is the case, the first thing I would check is that the rim has been machined for a single sided hub rather than a later full width hub. You have to look very carefully but, for the latter type of hub, the set of nipple angles will be the same on both sides.


DAVE BRADY

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Re: 1955 b31 wheel offsets
« Reply #2 on: 17 May, 2022, 07:46:49 »
Hi,

Just a comment on the tyre/rim size.  I believe the WM2 is correct for a 3.25 tyre and this would be standard for the front wheel ditto WM2 for the 3.50 rear.  WM3 tended to be used for 4.00 x 18 tyres. 
Which Avon are you fitting?

Dave.

Bess

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Re: 1955 b31 wheel offsets
« Reply #3 on: 17 May, 2022, 11:31:04 »
Hi,
    Originally it has rim part no. 67-5543 or 65-5870 wheel complete. If fitted, is the offset 2.230" C/L of rim to edge of brake drum.

Best wishes...

mashermick

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Re: 1955 b31 wheel offsets
« Reply #4 on: 27 May, 2022, 20:30:57 »
Ordered a wm3 and spokes for 7in single side hub ,laced up OK, I was told there is a right side and a  wrong side ,couldn't see any difference ,trued up OK  no angled spokes this time! New 3.25 avons seems OK supplier is going to give me a credit for the wm2 which I think is badly drilled

spaceman

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Re: 1955 b31 wheel offsets
« Reply #5 on: 28 May, 2022, 07:52:30 »
It's only the single sided front hub that is fitted with a rim that has a right and wrong way round - if the bike is fitted with a full width hub then it doesn't matter which way round the rim goes.

EDDIE SIMPSON

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Re: 1955 b31 wheel offsets
« Reply #6 on: 29 May, 2022, 00:23:19 »
i have yet to buy a rim for a bsa that laced together perfectly like an original dunlop. recently i bought spokes and rim for a super rocket full width hub and the drilling was perfect and laced up really well. however the dimples in the rim were not as central as the dunlop rims and i had to grind some of the spoke nipple as well as the protruding spokes to give a smooth rounded surface for the inner tube. another issue is being supplied with larger 4mm spokes rather than butted spokes that meant the spokes were never in contact when they cross. if you question anything with the manufacturers over the phone they can bounce you by telling you to take it to a  wheelbuilder with years of experience.
without dunlop and the original jigs i guess its all a compromise replacing rims.

spaceman

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Re: 1955 b31 wheel offsets
« Reply #7 on: 29 May, 2022, 07:05:13 »
My experience has been a little different. I have rebuilt several dozen wheels over the last 10 years or so and have always been amazed how accurately they have gone back together. In fact, it was very rare to have even needed to grind back the ends of the spokes because they were too long. All but one of the spoke and rim sets were bought from CWC with the exception being a set that I bought from the Devon Rim Company during lockdown because CWC were closed down.

EDDIE SIMPSON

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Re: 1955 b31 wheel offsets
« Reply #8 on: 29 May, 2022, 23:13:34 »
i had exactly the same issue as the original post with a bsa a7 7 " single sided  rim. spent ages on build. tried reversing the rim with little change and one set of spokes were too long and another slightly too short. i should have sent the whole thing back but i was desperate to get the bike on the road and settled for a bodge job. i was copying the same bsa spoke pattern and i found a post on another forum that had the same issue as me . it seems the rim producer i bought from does not necessarily use the standard rim spoke pattern but can have their own version. my fault for not consulting the manufacturer but a lot wiser to the pitfalls .
on the subject of wheel building , about 30 years ago i went to vic nunns in surbiton [ wheelbuilder ] to buy some replacement broken spokes on my trident and what the friendly old boy did was match the spoke size and length and then hand tap the curl on the end of the spoke  on his old blacksmiths vise. it took him seconds to bend each spoke perfectly.