I recently did a poorly landed 5+’ drop, and bent my right snafu pedal (or possibly my profile crank, however unlikely). I have also bent the spindles on a set of wellgos and I’m not sure, but also another snafu. I am tired of breaking stuff, as there’s no reason to do so. So my question is a rather simple one:
How feasable is it to fabricate one’s own pedals? What features would one want in them, and what materials would you use? Sealed cartridge bearings, or custom seals?
I’m thinking of a 4130 chromoly spindle, or titanium, depending on which is cheaper to heat treat. As for the material of the body, I am thinking aluminum and rubber. Possibly magnesium if it’s easy enough to obtain, but aluminum seems the best bet both for strength and durability and accessibility.
As for the bearings, I’m thinking custom o-ring seals on the outside would be more than easy, and on the in-side a rubber flap that srings on the axle to keep mud and grit out. A good packing of grease on the other side could provide a backup protection. I think cartridge bearings, such as on Wellgo b-37s, are inferior because of their lateral weakness.
As for the pedal body designs, I was considering a custom, non-symmetrical design. On the left (pedalgrab side) pedal, one side would be amply pinned, while the other side would have a small triangular reccess in it with rubber lining so as to facilitate stability on round rails. The edges would be pinned for grip in wood. I don’t grind, and have no need for good sliding. On the right side, a normal, symmetrical parralleogram design seems ideal. Plenty of pins of course.
Please, if you have any input on the topic, I’d like to hear it.
You might want to consider the Gack Juggernaught pedal. It’s expensive, but looks very strong. The axle is oversized and maintains that oversized diameter for the entire axle (except for the 9/16" threads). MSRP is something like $130.
Ryan Atkins was using a pair of Specialized platform pedals at the CA Muni Weekend. He was using last year’s model. This years model has some changes to improve durability. You could ask him how they’ve been holding up. They’re supposed to be strong. MSRP is $82.99.
You can only get so strong with pedals. The limiting factor is the 9/16" threaded pedal hole. You can make the rest of the axle oversized, but you still have to make the threads 9/16".
Making your own pedals would be expensive and time consuming. And you’d have unpredictable results and probably a few design duds at first.
I imagine there would be many duds. I have time, not money, sadly. I was thinking about that limit of the threads, and i guess there’s no real way around that. Still, it’d be nice to have a pedal that actually grips round rails when you pedalgrab them. It’s really frustrating to end up doing a crappy grind when you are trying to pedalgrab something.
One design feature to strengthen up the area around the 9/16" threads is to put a lip all the way around the area where the pedal spindle makes contact with the crank. Look at the spindle for the Specialized pedals. There is a lip all the way around next to the threads. That lip snugs up to the crank and gives more support around the threads. Lots of other pedals put the flats there for pedal wrench. That gives less support in that crucial area and makes it more likely for the pedal spindle to flex or bend there.
it dosen’t seem like pedals would be too hard to make. the only high tolerance areas are where the bearings seat on the pedal body and spindle. if you could get a solid block of aluminum and cromo rods then had the high tolerance areas CNCed for you (expensive) then everything else could be done with simple tools.
if you took a pair of exhisting pedals you could tap one side so that rubber from an old tire or something could be bolted on. that might be a cheap solution to your crappy grinds.
Why? Trying to figure out if he just doesn’t understand why we use splines where we do…
Yes, like skippi says, you can always think big and take in the whole picture. If the threads are the weakest point on a set of pedals, perhaps unicycling will move to a larger size someday. You can customize some existing cranks, or make your own. Or go the whole nine yards and make the whole hub and crankset. Tom Miller made some super-strong one-piece cranksets for abusive unicyclists many years ago. Not sure how they compared to todays’ splined stuff, but they were a sensible solution before we had access to splines.
I did some research into the technology used to fabricate crank splines a few months ago, and it’s well beyond most well-equipped machine shops’ capability to do so. The technology is the same as is used for making the bronze blocks that Bridgeport ACME leadscrews thread into. I would need access to a specially equipped tool called a broaching machine. All they do is cut stuff like splines. In order to build my own unified pedal/crankset, I’d have to furst build a broaching machine that could cut splines with an accuracy of +0.0000", -0.0005". That’s far more difficult than simply finding alternative methods of pedal designs.
A 1 piece pedal/crankset desgin has many drawbacks:
-If you break the spindle on one of your pedals, you are thoroughly screwed.
-It limits you in material choices, since you must use the same material for the pedal spindle as you use for the crank.
-You have to temper the pedal spindle and crank to the same hardness, which isn’t neccessarily ideal.
I’m sure there are other drawbacks, but those seem the most obvious. I think that tianium would be a nice material for a pedal spindle, but I imagine it would be awful for cranks (although it’d be the closest we ever came to built in shock absorbers due to flex). I have never heard of splined titanium cranks, and I bet there’s a reason for this. There is the chance that the technology doesn’t yet exist to broach profile splines (special because they are extremely small) into titanium. I have heard that titanium flexes so much that in order to make accurate bottom brackets for titanium bikes, you must start with a giant, oversized block of titanium to minimize flex. Then, once the BB is cut, you machine the rest of it down. That isn’t feasible for a crank.
I like John Childs’ point about the ring on the specialized pedals. I noticed how the wrench surfaces on my snafus DO weaken the spindle, but it doesn’t seem that the threads were where my pedal bent. It seemed to bend at the inner bearing race.
I am fine with Evan taking a shot at making the pedals, since he won’t succeed at his current rate.
The titanium pedal spindles I’ve seen have all been for the weight weenie cyclists who are more concerned about grams than strength. The titanium pedal spindles had max rider weight limits and were not designed for hardcore use. They are aftermarket titanium spindles designed to replace the stock steel spindles in specific pedals.
You’d have to make the titanium spindle larger in diameter than the steel spindle to get the same strength. CrMO steel is better when you’re going for strength.
Since I read this thread I’ve always been under the impression that per unit of material, titanium was 2x as strong as steel or chromoly. It will flex far more, but ultimately be just as strong if not stronger.
No, it is much stronger per gram/pound/stone/whatever, but the titanium pedals etc. are all made for lightweight cyclists because titanium is ideal for that sort of thing. In other words, there is much LESS material in stuff made of titanium because it’s designed for lightweight “weenies”.
By that logic there shouldn’t be any reason not to make a ful thickness ti pedal spindle. It would be far stronger and be of comparable weight. What made you think I’m designing my own pedals for weight savings?
> By that logic there shouldn’t be any reason not to make a ful thickness
> ti pedal spindle
Titanium, feh. Get your mitts on some Aermet alloy - the stuff they
use in F-18 landing gear. It’s crazy strong, somewhere around 3 times
as strong as CrMo if I read the specs right. Basically off the chart.
Excellent durability and good corrosion resistance. Perfect for your
pedal spindles. If you can obtain it, machine it, and heat treat it,