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clipless pedals for 1/2" threaded cranks?(10 posts)

clipless pedals for 1/2" threaded cranks?timfire
Apr 29, 2002 8:17 AM
I actually have an old & cheap mountain bike that has a 1-piece crank with the smaller 1/2" thread size. I was hoping I might be able to find a pair of clipless pedals that I could put on it. Anyone know of any pedals that would fit this size crank?

I know that some BMX cranks still use this size, but a quick internet search did not yield any clipless pedals for that size.

I thought maybe someone here might have had the same dilemna with wanting to put clipless pedals on an older-sized crank.


--Tim Kleinert
BB conversionStraightblock
Apr 29, 2002 8:53 AM
I've never seen 1/2" clipless pedals. BMX shops carry or can get a bottom bracket that converts a one-piece crank to 3-piece. I don't know how much you want to spend, though. By the time you buy the bottom bracket, a cheap crankset & pedals you probably could have just bought a good used mountain bike at a yard sale & put on some $20 Ritchey clone pedals from Nashbar, ended up with a better bike and been money ahead. How about going with toeclips & straps?
take it to a good old fashioned bike shop.....Spirito
Apr 29, 2002 9:23 AM
that has experiance in reaming and threading and such.

1/2" is smaller than 9/16" and it is not a big thing todrill and thread it for the larger more acceptable size.

if your parts are fine it may be easier to do this than change crank and bb parts and should hopefully be a lot cheaper.

that way you can use any 9/16" pedal combo you like.

I wouldn't do that if it were my bikeStraightblock
Apr 29, 2002 10:43 AM
That's a highly stressed point to be removing material from a cheap component. Tim didn't say how much he weighs or how he uses the bike, but if he rides with clipless pedals it's likely he'll ride it hard. To me, it sounds like a catastrophic failure waiting to happen. If he can't replace the bike with something better, I still think 1/2-20 platform pedals with toeclips or powergrips are a better idea.
1/2" (8/16") isnt much diff to 9/16" - "catastrophic"??? NmSpirito
Apr 29, 2002 10:51 AM
I used to work at the LBSStraightblock
Apr 29, 2002 11:05 AM
and that's where the one-piece cranks break--at the pedal thread. Potentially catastrophic? Yes.

You're right, 1/16" isn't much, but it's a significant percentage of the cross section of the crank at the pedal hole. Like I said, I wouldn't do it to my bike, and I doubt a reputable LBS would do it, either.
granted that i have no experience with one piece cranks..Spirito
Apr 29, 2002 11:27 AM
i cant say for sure but i have owned a few french threaded cranksets with smaller holes and have had them simply and successsfully enlarged and re-thread to the larger and standard 9/16" size. many that have had the same french threading have done the same and ive yet to hear of failure on these.

and to quote sheldon brown on this

"Older French bicycles used a different, smaller diameter where the pedal screws into the crank. The vast majority of French bicycles imported into the U.S. used standard 9/16" x 20 crank threading, but if you find an older bicycle that was bought in France, you may run into this problem. The French-thread cranks can be tapped out to 9/16". French pedals will often be marked "G" (Gauche=left) and "D" (Droite=right)."

if 1/16" will result in the failure of the cranks for the original poster i would advise him not to ride them at all. i still think it would be fine.

my lbs could do it easily and they have the tools and knowhow. an engneering shop could do the same as well.

re: clipless pedals for 1/2" threaded cranks?gtx
Apr 29, 2002 1:11 PM
Sheldon did it
Thanks everyone.timfire
Apr 30, 2002 6:04 AM
Thanks everyone. FYI, I am about 185 lbs and just wanted the bike for a beater/rain bike. Thought I would get some slick tires, a new seat, fenders, etc. and maybe throw on some cllipless pedals.

I realize that in some ways it would be easier just to try and find a different used bike, but I already have this one and it is relatively un-used, so I thought it would be better just to try and find parts for this one.

I might try and email Sheldon Brown and ask him what he did.

I have a few more questions concerning the cranks/ BB, but I think I might ask them on the components forum.

Thanks again,

--Timothy Kleinert
A little more from Sheldon Brown, plus a leadStraightblock
Apr 30, 2002 8:51 AM
From this link Sheldon Brown replies to someone who wants to use clipless pedals on an exercise bike with a one-piece crank:

"Another poster suggested tapping the cranks out to 9/16", but that won't
work either. The reason they use the smaller thread on one-piece cranks is
that the crank has to be thin enough to slip through the bearing cones so
that it can be installed into the bottom bracket. This precludes making
the end of the arm thick enough to acommodate a 9/16" pedal. I'm afraid you're S.O.L..."

But further down the page, another poster says 1/2-20 clipless pedals are available from a company called J & B Importers. I checked their website and it lists 1/2 clipless but shows them out of stock. You might give them a call or e-mail. Good luck.