UniGeezer

All the pedal tap sets I see online are described as for cleaning out old threads only. I've yet to find any taps online that are actually used for cutting new threads in bicycle cranks. Does anyone have a link to where I can find a set for this purpose?

squirtdad

what are you trying to do/fix?

if your current threads are hosed cleaning out is first step, but you cant just recut the threads as there is no material to cut into.

what shops used to do (sure some still do) is drill out the threaded hole and put in a helicoil of the right size a drill press is recommended as an off center hole on a pedal will be super irritating

TPL

Are you going to begin manufacturing cranks ?

The maker of your CNC machining center will supply tooling for you

Iride01 

The threading isn't really specific to bicycles. You just need to find some 9/16 x 20 taps in right and left hand threads.

If you are only doing one hole each, those are going to be some pretty expensive holes. Taps are not really anything the average DIY bike mechanic needs. And not really your average pro bike mechanic.

So out of curiosity, are you making your own crank arms?

I use to order a lot of stuff from these guys....

https://www.mcmaster.com/taps/thread-size~9-16-20/

Bill Kapaun

They are simply 1/2" or 9/16" X 20 tpi taps.
The LH thread is the more difficult to obtain.

UniGeezer

The black cranks came as single hole 165mm and I tapped the shorter holes myself using the park tool tap, although it says they're made only for cleaning out old threads. The silver cranks in the foreground were dual hole already and I tapped the third and shortest pedal threads at 110mm using the same taps. The reason I'm looking for specific cutting taps is because the park tool taps, although they work, may break if continue to use them to cut new holes. Btw, I used a 33/64 drill bit to drill the initial holes.

canopus 

Hozan makes some, plaza japan would probably be the best way to order them ( i haven't looked lately though). Get a good specific thread cutting oil and the parks should be fine, especially for aluminum cranks. Most will not list for cutting, only cleaning. That absolves them when they fail. HSS is best for cutting.

pdlamb

I suspect the same can be said for any other taps. They'll never break sitting on the shelf!

Crankycrank

I'm not a machinist or an engineer but I might be a little concerned about the reduction in strength of those cranks with the extra holes in them.

UniGeezer

I don't use them for anything extreme, like drops, but the 150/127mm dual hole cranks (polished 7050 aluminum) are rated for extreme use. But adding the 3rd hole so close to the 127mm hole would void that claim. They work just fine for hill climbing and long distance though. Since my 700c unicycle is fixed, I use the 150s for steep climbing, then switch to the 110s for the ride back down, flats and moderate hills.

squirtdad

Thanks for that...that clears that up..

in my limited experiences with tapping (or thread cutting) a tap is a tap, there is no real difference between cutting and cleaning. you just have to start with the correct size starter hole and then go slowly, get the tap started square, lot of oil, go forward, then back out, then forward a bit more, then back.....

SoSmellyAir

Yeah, especially the third crank (from the top); look how little material there is between the left and middle holes.

markwesti

At UniGezer , All Industrial Tool Supply (in your back yard , they ship) has the tap you need for about $20 . It is High Speed Steel precision ground .
https://allindustrial.com/products/threading-tools/
Mark .

squirtdad

taps....need righ and left as pedal thread direction is different between right and left cranks

UniGeezer

They look closer than they actually are due to the outward flair of the bevels at the top of the holes, plus the scratch marking from where the pedals tighten and seat against the cranks. Those are 7050 solid aluminum, so that spacing is not likely to pose an issue, at least not the first 800 miles so far. 🙂

SoSmellyAir

Are you trying to inspire me to make some "speed holes" in my Cannondale SI crank arms?

3alarmer 

.
...Hozan makes the best pedal taps for cutting threads into a virgin surface.
They are long taper taps, not plug or bottoming taps, so they are a better choice for what you're doing.

https://www.ebay.com/itm/23421749942...75.c101224.m-1

veganbikes

I would not want to find out. Especially not on a unicycle yeeesh.

If you want shorter cranks you might reach out to Lennard Ziin, he and his company does do custom cranks and I bet you could get them in ISIS either through him or Joseph Kuosac (who I think he might use for some of his stuff anyway). I also see that Kris Holm does short cranks as well even has a 110mm length and they look like really nice cranks and some neat Unis which I kinda want.

In terms of tapping if you need new threads typically that is done through Helicoil. I am pretty sure I saw this above but to reiterate you need material to create threads so the Helicoil insert provides that when you have trashed yours (which I did recently on a NDS arm which is being replaced under warranty)

UniGeezer

The polished alum cranks I posted are Kris Holm Spirit cranks that came dual hole 150/127. I also have the 165/137, 137/117, and 127/110. The Spirits are also disc rotor ready, and they are made for outboard disc brakes, which most of my unis have. I simply wanted to make "tri hole" cranks since the two sizes I use most are 150/110, but that combo isn't available so I made it myself.

dedhed

If you don't want to wait for china shipping

https://carsoncitybikeshop.com/tool-...saAqhUEALw_wcB

veganbikes

I don't see why you would need to move pedals around that much you need three holes. Granted I just went with some shorter cranks on a bike but I am set now all is good. However I am not a unicyclist so maybe there is some trickery behind that.

UniGeezer

Bikes, for the most part, have gears, often more than 20, so pedal hole changes aren't necessary. And the lowest gears make steep climbing much easier than 1:1. Unicycles, on the other hand, being 1:1, are not geared (with the exception of Schlumpf unicycle hubs but those step up to high only, and no low gear) so the longer crank holes offer better leverage for steep climbs, and the shorter holes are ideal for flats and some incline. I've climbed Fargo st over 10 times and without a low gear it's an absolute killer climb!

veganbikes

So would you stop and swap pedals mid-ride? or more of a I know I am going to be hilly I will swap around before I start? That guy who pedaled around the world on a Unicycle from England who's name is escaping me I think had just one pedal hole (Ed Pratt maybe).

Something like this might be just the ticket: https://highpath.co.uk/cycle-crank-shorteners/. They can also shorten certain crank arms which is kinda cool.

UniGeezer

Yes, it was Ed Pratt. I'll be doing my 11th 100 mile unicycle century sometime in February, and I do these all-day rides on a 36er unicycle with 110mm cranks. Not sure but I think Ed probably opted for 127s to give a bit more leverage on hills. Really the only time I use cranks with multiple holes is for road climbing with my 700c uni. 150s up, 110s down. For shorter climbs like Fargo, or the top 10 hills in SF, I just use 150s up & back down, without changing holes.

veganbikes

Ok cool my memory didn't fail me YAY!

It is kind of like my first time doing a longer distance fixed gear ride. My plan was to get to a big hill and flip the hub over to freewheel but I got to the top and said you know what let me try fixed down and I made it and lived and was quite chuffed at the end. However on a unicycle it is probably a little different.