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Fender bolts for 1973 Raleigh Gran Sport

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Fender bolts for 1973 Raleigh Gran Sport

Old 10-14-21, 05:25 AM
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furiouschads
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Fender bolts for 1973 Raleigh Gran Sport

M6s are just a little too big. M5s slide right through the holes both front and rear. The holes are threaded. What is the correct fender bolt for these bikes? Yes, I can put a nut on the M5s, but I would prefer to do it correctly.
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Old 10-14-21, 06:34 AM
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I'd guess some sort of Whitworth bolt, but I'm also surprised that M5 is too small. I've usually found on those old Raleigh road bikes that M5 is too large. I'd re-tap for M6.
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Old 10-14-21, 07:02 AM
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What does an American 1/4"-20 bolt do in the hole? Can you "start" an M6 but it quickly binds up? Or does it not even catch the thread? Being that a M5 slides right through, it'd have to be at least Whitworth 1/4" if it's Whitworth, and an American 1/4-20 bolt may screw right in.

Could be Whitworth or could be some other odd British size (British Standard Cycle and British Association are other ones I've seen on bikes).
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Old 10-14-21, 10:12 AM
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On my '73 GS 5mm fit the rear but was too small for front. I retapped those for M6. You do what you gotta do.
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Old 10-14-21, 07:55 PM
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Originally Posted by scarlson View Post
What does an American 1/4"-20 bolt do in the hole? Can you "start" an M6 but it quickly binds up? Or does it not even catch the thread? Being that a M5 slides right through, it'd have to be at least Whitworth 1/4" if it's Whitworth, and an American 1/4-20 bolt may screw right in.
.
Yes, an M6 starts but it immediately binds. I'll try a 1/4 20 before tapping them all to M6.
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Old 10-14-21, 09:24 PM
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Originally Posted by furiouschads View Post
Yes, an M6 starts but it immediately binds. I'll try a 1/4 20 before tapping them all to M6.
All right. Let us know what you find out! One other thing to note is that, if it's a similar size to M6 (which it is, because you can get an M6 bolt to start), retapping them for a 1mm pitch could basically destroy the threads inside, leaving your bolts precious little to hang onto. Because the existing thread is either coarser or finer than M6 standard pitch, which is 1mm per thread, the tap will cut threads out of the threads that are already there, and may not leave much metal. I hope that makes sense. I'd throw everything at these to see - #12 x 24 is another oddball close to M6, as are 1/4-28. If it's none of these, it's probably BSF or BSC, and tapping may be your best option. If the M6x1 tapped hole quickly strips, you an always increase it to M7.
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Old 10-15-21, 06:50 AM
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I'd go with M5 and a nut. I understand the desire to 'do it right' but I don't see how changing the threading in the frame is better than something that's completely non-destructive. But as @due ruote said... you do what you gotta do.
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Old 10-15-21, 06:42 PM
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Originally Posted by furiouschads View Post
Yes, an M6 starts but it immediately binds.
Try from the other side if it binds - you might have a bashed thread at the beginning.

My GS also has different sized holes front and rear, haven't bothered to find out what they are...
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