Pedal threads

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robert17
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Pedal threads

Postby robert17 » 17 Oct 2020, 8:06am

People, the next chapter of my restoration learning journey is that the lovely Stronglight chainset a kindly forum member sold me, requires 14 x 1.25 threded pedals, not the now standard 9/16. Doing some research, it appears that such pedals are rare and that tapping the crank threads out to 9/16 would be the way forward.

Well that's fine except tapping is something I've yet to try, Indeed I don't have the tools. Is this an easy task or would I be better off paying someone to do it for me?

Thank you.

Robert.

iandusud
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Joined: 26 Mar 2018, 1:35pm

Re: Pedal threads

Postby iandusud » 17 Oct 2020, 8:31am

You could buy a pair of taps from around £20 and you shouldn't have any difficulty using them. However as you are not likely to have much use for them again it might make more sense to get a local bike shop to run their taps through the cranks.

Jdsk
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Re: Pedal threads

Postby Jdsk » 17 Oct 2020, 8:34am

I've just done my first tapping on the notorious tandem trailer trike.

iandusud wrote:You could buy a pair of taps from around £20 and you shouldn't have any difficulty using them. However as you are not likely to have much use for them again it might make more sense to get a local bike shop to run their taps through the cranks.

Exactly, unless you think you'll be using them again.

Jonathan

robert17
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Location: Worcs

Re: Pedal threads

Postby robert17 » 17 Oct 2020, 8:41am

Do you have any ideas how much that would cost? Does not appear to be a big job.

David9694
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Re: Pedal threads

Postby David9694 » 17 Oct 2020, 8:47am

You’ve presumably read Sheldon Brown?

Older French bicycles used a 14 mm x 1.25 mm thread, but these are quite rare. French-threaded pedals are commonly labeled "D" and G" (French for "droite" and "gauche" (right and left). A French pedal will start to thread into a 9/16 x 20 crank (and vice versa), but will soon bind. Do not force it, or it will damage the crank. Aluminum French cranks are easily rethreaded to 9/16" x 20 TPI.

From my experience of trying to re-tap a damaged crank thread for a helicoil, you’ve got to get or keep the 90 degree angle spot on, or you will get that queasy feeling that something is “off”.

robert17
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Location: Worcs

Re: Pedal threads

Postby robert17 » 17 Oct 2020, 8:55am

They are marked 14 1.25 on the back.

Brucey
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Re: Pedal threads

Postby Brucey » 17 Oct 2020, 9:54am

it is possible that the cranks have already been retapped to BSC; have you tried a pedal in them?

BTW retapping is, in this case, a five minute job.

cheers
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Cyril Haearn
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Re: Pedal threads

Postby Cyril Haearn » 17 Oct 2020, 9:56am

I should be afraid of damaging the thread so the cranks could no longer be used
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robert17
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Location: Worcs

Re: Pedal threads

Postby robert17 » 17 Oct 2020, 12:42pm

I tried a new pedal, but they bound quite quickly, so stopped.

Brucey
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Re: Pedal threads

Postby Brucey » 17 Oct 2020, 5:07pm

you need the thread retapped, French pedals or different cranks then.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

robert17
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Location: Worcs

Re: Pedal threads

Postby robert17 » 17 Oct 2020, 5:27pm

I've found someone to retap the threads. A bike shop I won't name wanted to drill a larger hope and glue in an insert with a 9/16 thread! Thanks but no thanks I said. The guy told me that this what he does for cranks with damaged/stripped threads.

alexnharvey
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Re: Pedal threads

Postby alexnharvey » 22 Oct 2020, 9:08am

robert17 wrote:I've found someone to retap the threads. A bike shop I won't name wanted to drill a larger hope and glue in an insert with a 9/16 thread! Thanks but no thanks I said. The guy told me that this what he does for cranks with damaged/stripped threads.


It's not a shameful suggestion and such inserts are a common repair for damaged threads in cranks and all sorts of other parts and devices. Threadlocking agents are essentially specialist glues.

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Mick F
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Re: Pedal threads

Postby Mick F » 22 Oct 2020, 9:21am

Brucey wrote:you need the thread retapped, French pedals or different cranks then.
Yes, I agree.

Cheapest option is to buy French pedals perhaps.
They must have all the same pedals as the rest of us, just different spindles.
Mick F. Cornwall

Brucey
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Re: Pedal threads

Postby Brucey » 22 Oct 2020, 11:46am

alexnharvey wrote:
robert17 wrote:I've found someone to retap the threads. A bike shop I won't name wanted to drill a larger hope and glue in an insert with a 9/16 thread! Thanks but no thanks I said. The guy told me that this what he does for cranks with damaged/stripped threads.


It's not a shameful suggestion....


I agree, but it is a pointless one.

FWIW I think I have a set of French-threaded (vintage) pedals here.

cheers
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fastpedaller
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Re: Pedal threads

Postby fastpedaller » 22 Oct 2020, 12:43pm

Mick F wrote:
Brucey wrote:you need the thread retapped, French pedals or different cranks then.
Yes, I agree.

Cheapest option is to buy French pedals perhaps.
They must have all the same pedals as the rest of us, just different spindles.


No they have Frogs Feet - so quite different :lol:
Not intended to be offensive, I'll add