colombo357

Well maybe try harder then.

And yea, all products are the same. There are no differences in quality on any product, ever. Walmart bikes are as good as the best of them.

Skipjacks

Generically speaking....

I just got a pair of 20mm pedal extenders and they are a game changer for my knees.

I absolutely did not believe that 20mm could possibly make much of a difference.

I was so wrong

One of my knees was always killing me. Not just when I rode but pretty much all the time. I figured it was scar tissue building up from having ACL surgery 20 years ago. And I assumed biking was making it worse but I didn't think biking was the problem.

I had to wear a brace when I biked or it would always be 10 times worse afterwards.

On a whim I got pedal extenders. (Actually it was after reading an article on knee pain in Bicycle Magazine. Free subscription. Only reason I read it.) And INSTANTLY there was a difference.

My pain was on the side of my knee...the side facing the other leg. (So left knee...right side of left knee). The article I read said pain there means your legs aren't straight enough on the down stroke when biking.

The 20mm made all the difference in the world.

I got these 6 weeks ago and I stopped riding with my knee brace immediately. I haven't had the slightest bit of knee pain since. Not on the bike. Not walking. Not hiking up hills. Nothing.

Turns out the biking was 100% of my knee pain problem and the pedal extenders eliminated it in 1 day.

My knee hasn't felt this good in years

timtak

If that were true it would be a shame because I am proud of my bicyclular innovations. I would prefer a crankarm sized aluminum washer for weight
and aesthetics, adonized bright red.

My knees feel really good too. My pain was on the inside of my knee too. Looks like we have found the culprit.

I also found (as mentioned on the over 50 thread)
1) That my knee pain is associated with a longer crank arm. Only 172.5 as opposed to 170mm but it seems to make a difference since the pain comes at the top of the pedal cycle when using that longer crank. Now I wonder whether my riding bow legged was in order to increase q factor, or whether it was just to avoid bending my knee to the same angle at the top of the pedal stroke. I will experiment with lower washer heights.
2) I also had Biopace chainrings rotated, away from the Biopace recommended, knee-saving position, to one which puts the most stress on the knees at the downward push position. I will rotate my biopace chainring back to its intended knee-saving position.

Sweetheart14

Hi Claude,
Well after some time, we have the French thread done. Well the male end is 14x1.25mm and the female end are 9/16-20.We have made some in 20mm, 25mm, and 30mm. We have had a terrible time getting American certified stainless steel. The price and availability for the material has gone crazy. It has been difficult to keep up with all the orders and make something new. We finally found a vendor who keeps the material in good supply. So we placed a large order and have been machining for some time. We also have changed the washers to stainless steel. So if you are still interested. Let me know or you can go to our ebay site.

Thanks

timtak

I found that the most important thing is, not that there is a long extender, nor even increasing Q factor, but rather ensuring that ones toes are rotating away from the bike. Extenders encourage and facilitate this outward rotation. But so does a thin washer. I am currently using a 2mm washer on my right pedal axle and attempting to rotate my right heel inwards, towards my BB just a little. This has been enough (together with various types of exercise) to reduce or almost eliminate, my knee pain.

Sweetheart14

If the washer alone helps. That is great. I got started in this when my husband made me a set of 20mm long pedal extenders. It made riding my bike so much easier and more comfortable. Since he made me the 1st set. I tend to ride more often and longer.

Sweetheart14

It took a few tons of pressure to break the crank arm. It bent 1st.

Sweetheart14

One of the advantages of the hollow pedal extender. Many pedals are installed with an 8mm allen wrench. If the pedal extender is solid you can't install the pedal. Another is looks. It looks clean with no flats.

Novalite

Stainless steel (most common / cheapest grades 304 and 316) has a few things to take into account.
1) It's quite weaker than common grade steel (50%)
2) In the presence of an electrical conducting fluid (water) it can dissolve aluminium from bikes frame / whatever to white powder.
3) Stainless steel can still corrode if its surface is hindered to form the passivation layer it normally protects from rust. A typical example is people using stainless steel bolts but don't have the additional mounting stuff (such as washers etc), so they use a common steel washer instead. The stainless under the washer will rust alike it isn't stainless.

So what grade stainless steel do you talk about here?

Novalite

Was that crank arm from aluminium?

Sweetheart14

There is a difference.
Most of the box stores buy their stuff from China. They pay pennies for it. The $5.00 pedal extender. The old saying comes to mind. You get what you pay for. Ours are a bit more expensive. We make them We only use American certified materials.

Sweetheart14

Yes the crank arm we used was aluminum. It was a cast aluminum more than likely Grade A380.

Sweetheart14

We use grade AISI 303 for many reasons. While 304 and 316 is the most common grades they are not the cheapest. Well the 304 is lower cost than most. 316 is one of the more expensive grades. Until you start getting into the 400 series of stainless steels.

Psi = per square inch. Elongation at Break = How much it will bend before it breaks.

AISI 303 Stainless Hardness on the Brinell scale 228 AISI 1018 steel. Hardness on the Brinell scale126

AISI 303 Stainless Tensile Strength, Ultimate 100,000 psi AISI 1018 steel. Tensile Strength, Ultimate 63,800 psi

AISI 303 Stainless Elongation at Break 40% AISI 1018 steel. Elongation at Break 15%

These are just a few comparisons of what is commonly known as cold roll steel to stainless steel.

I think you have your comparisons backwards. Unless you are thinking of medium to high carbon steels. AISI 303 can go toe to tow with a few medium carbon steels.

As for the galvanic response (corrosion). You are correct. Well in a way. Stainless to aluminum will over time corrode to each other. It only becomes a problem under two conditions.
1. It stay wet and is not maintained over an extended period of time(outdoors for a few years).
2. You leave your bike in the ocean for a few months. With most, they will never see this problem.

I have had mine on my bike for almost 5 years. Not one problem.

We have been looking into electro-polishing our pedal extenders. One added benefit is, it will also passivate the pedal extenders. A light film of corrosion protection.

Kristian.

Novalite

I didn't have my comparison backwards.
https://www.machinedesign.com/materi...d-other-metals
Grade 303 is a tad 'worser' - the difference with 304 is sacrificial (strength / corrosion resistence) in order to allow easier machining.

Stainless and aluminium don't corrode "eachother", nothing happens to the stainless side of the galvanic corrosion - it's just the aluminium that dissolves to white powder, so it can ruin aluminium frame / crank mounting holes. A very common example: take out an inner tube - it has a stainless steel valve that goes through a hole in an aluminium rim. See the white dust on the valves thread. That's alu from the rim - the hole got bigger.
My current bike stand was mounted along 2 grade 304 (A2-70) bolts+nuts, through an aluminium block between the frame tube and the stand. My stand kept on losing, until the point I had to retension it several times in an hour when having parked alot. The holes in the alu block and the stainless bolts hung full of white powder. Just to say - it's something to take into account, in an aluminium bicycle frame/part and all weather case. Thread in the frame can get damaged meaning a loss of mount points.
Electro polishing is just irrelevant to galvanic corrosion.

Novalite

The thread of a pedal has a certain length. Shortwhile ago I decided to insert pedal washers (to avoid cracks development in the cranks around the pedal mounting holes). Thing is, you lose some thread engagement. You say here that you use 4.5 mm washer, your pedals must have had extraordinary thread length then?

timtak

They were standard Shimano pedals. The were only engaged by about half the pedal length! But I weigh about 64 K.g. and I guess that some people are nearly double that and ride bikes. The pedal did not break and now I am using a 2mm washer.

For those of us that use pedal extenders to help their knees, I think that the point is to ensure that you do not bend your knees in to avoid pushing at the top of the pedal stroke. The washer/spacer or a pedal cleat wedge dis-encourages that tendency. I have shortened my cranks, been climbing stairs three at a time, and attempting to put a bit of outwards torque on my legs and lately my knees have been okay.

No one is interested but, I think perhaps my knee pain was related to decreases in testosterone. I am 55 so my testosterone levels are, I presume, on the way down. As I attempt to pedal "with outwards torque," without damaging my knees I get the feeling that I am engaging in primate crotch display, or conversely, when I was damaging my knees, I was not.

Sweetheart14

"In stainless steel, passivation means removing the free iron from the surface of the metal using an acid solution to prevent rust."

"Your example of the stainless steel valve in a aluminum rim, should point out to you. While is does have a galvanic reactions. It will go for years before it become a problem. And in most cases, there is water on the inside of the rim which will excel the reaction.In your case if you are getting that much galvanic reaction. You have something else going on."

"So lets look at your high strength materials. They are all great.
440C Martensite Stainless. Great material. Very expensive. Then you have the cost of heat treating it. Without the heat treating. The numbers are not so good for this application. Tensile Strength Ultimate is 110,000 psi. 4130 is 97200 psi and 303 has 100,000 psi not much difference. Elongation at Break. 440C before heat treat 2% and after heat treat 14%. 4130 is 25.5% and 303 is at 40% If we look at Shear Modulus 440C 12200ksi. 4130 is 11600ksi and 303 is 11200ksi. Again for the added cost there is not much difference. "

"If we made pedal extenders out of 440C. We would not get a lot of benefit for the cost difference. There are some pedal adapters made from 4340(close to 4130. 4340 is just a bit better grade)."

"Next time you make a statement. Comparing 303 to aerospace metals that most will never experience in the bike world. Well a few might see bit of 440C if they have a nice stainless steel knife. None of the metals you copied and pasted are considered common metals. Common metals are 1018, 12L14, 1144, A36, 303 and 304 stainless steel. We have been making things in metal and plastic for over 30 years. For people like Lockheed Martin and Harley Davidson. For every 10 ton of common metals, we will use a pound of the medium to high carbon metals. When we buy 1018 for example we buy full length bars, even if we only need a few inches. One reason most place only sell it buy the full length. Industrial suppliers. When buying 4340 or 4130, 440C, A2, D2, and S7. We will only buy the exact amounts. If we need a few inches, they sell it buy the inch."

Mosyosalyangoz

You can find it on Ebay

jzsoup

Paralyzed guy riding a handcycle. I'm looking at 20mm sets on Amazon...any reason I can't/shouldn't link 3 of these together per pedal, to get the length I need?

Sweetheart14

You are looking for 60mm total length? As you put together a few extenders you have to make sure it is tight. Do you need your set to be hollow? I can make you a set that is 60mm long. For about the same price as buying 3 sets.

Miele Man

Have people using pedal extenders broken the pedal eye on their crank arm due to the extension and thus extra torque exerted on the pedal eye?

Cheers

Sweetheart14

Hello,
As far as we know. No one has ever had a problem like that. I guess that would depend on the quality of the crank you are using.


Thanks,

Kristian.

Juan Foote

In my own case, for more than VERY casual riding I use a leg whose setup have been adjusted specifically for use with the bike. It is a mess to actually walk on, but for me worked wonders, on bike.
I turned my toe in a good bit such that the heel would always clear the crank arm. I also lengthened the leg in relation to a "walking" leg to facilitate the lack of ankle flexion. It works SUPERBLY in the instance that I don't actually have to walk more than to the subway landing, car, seat in a restaurant.

I have interest in getting a pedal extender for my utility bike such that I can use with my everyday "walking" leg.

Sweetheart14

If you have a need for a length that is not standard, we can always make you one or a pair. Just let us know.

timtak

Above I thought that the pedal extenders worked for me -- reducing knee soreness -- because they encouraged me to ride rotating my toes outwards.

I have now come to the conclusion that the pedal extenders rotated my toes outwards, but it was fighting against this outward rotation, and rotating inwards, preventing myself from going bow legged, that prevented sore knees. In other words, pedal extenders encouraged internal rotation of the femur, to keep my legs and pedaling straight.

The extenders worked for a while but my femural rotational strength got worse.

I forgot about pedal extenders and tried all sorts of exercises squats, one leg Romanian squats (on a wobbly board and on a rotating platform), CARs, the McGill “big three” (hip abductions, flying dogs, side planks), hydrants, donkey and ninja kicks, and their combinations by the thousand.

Eventually, remembering the way that pedal extenders made me rotate my legs, feeling that scything, golf swings, and The Twist (Chubby Checker) helped, I concentrated on rotational strength, and with a banded leg twisting exercise, I have found that my legs are feeling a lot better - no sore knees, no hip problems, a real sense of leg youth and stability.