CliffordK

Your speed is related to the average power.

But your maximum force is essentially related to the instantaneous peak power, and someone standing and mashing can get much higher power peaks than someone sitting and spinning. Also as mentioned, higher force with slower cadence.

Other than the effect of the pedal falling away from a person's weight, one can put get pretty close to 100% of one's weight into the downward force when standing. Putting more force into the cranks than 100% of one's weight takes a lot of extra effort.

That is pretty light.

6'4" is pretty tall.

I'm not sure the height alone would increase the force on the cranks, unless you are using long cranks. 180mm or longer cranks. Even 175mm cranks are pretty standard and should handle typical forces. The difference between say a 175mm and a 180mm crank is only about 3%... not a huge force difference. There are longer cranks, but they are rare.

desconhecido 

It has been alleged that Jobst Brandt could be tracked by following the trail of broken Campagnolo cranks and Sturmey Archer hubs.

FBinNY 

We're going around in circles pointlessly.

The OP raised a question about STRENGTH, not power. I'm trying to respond by talking about the forces one exerts on the bicycle. You keep bringing up power which is something else entirely.

So, I'm happy to leave it here, and let anyone who cares, read what's been aid so far (see my post No.44) and draw their own conclusions.

friday1970

I have a friend that is quite heavy, pushing 350lbs plus. He has broken his bottom bracket twice by standing on the pedals to power up hills. Does that count for this thread?

keg61

PLUS ONE to the Nth power

AlmostTrick

These bike crushing stories make me glad I'm a lightweight and my gear lasts forever.

TreyWestgate

Also when I was 17 back then I could push that 24 speed mountain bike to 28 mph on a straight road for only being a mountain bike and not having smooth tires, so I must have been strong.

In the 42t ring which also didn't slip under lots of power, good thing!!.

Also I was able to outrun a 50cc kid,s honda dirt bike with it!!.

CliffordK

Only if the OP is carrying a 200 pound backpack while riding 20 MPH up a 20% slope.

My last chainring replacement. I determined it was the power stroke that was pulling the chain off the side of the ring. But, the actual cause of the problem was decades worth of wear, rather than a superman-like power profile.

alois

Things I have broken on my bike in the last 25 years:
-frames, multiple locations
-cranks
-rear axle
-pedal axle
-saddle frame
-countless spokes
-chains (I even broke the chain on a brand new bike I just had bought cycling down the street from the cycle shop)

I am 199 cm tall and most of the time had a weight between 120-150 kg. The answer is yes.

TreyWestgate

Really wonder what would happen if he opened full throttle. really he would be a good test for the different brands

TreyWestgate

So getting back to this thread here is what I do to REDUCE the torque loads.

1.ride on the BALL of my feet, not the midsole.

This greatly reduces torque.

2. wear softer soled shoes.

3. Run shorter crankarms.

4. Run lower gear setups.

5. increase tire psi, although does not make much difference in torque loads.

as of recently I have been able to ride geared bikes which is quite suprising since I wasn't able to do that before on many without the middle or small rings slipping out from the chain.

And especially since my once high torque would have only been made worse with the leg strengthening that riding single speed provides.

It simply was I think a matter of too much leverage torque that somehow exceeded the chain,s ability to keep up with the rings.

the natural looseness of the chain due to the need to shift from one chainring to the other was enough looseness that I was escaping it with my power.

Someday want to get my power measured.

Maybe the lucky part of all this is how unlike those who work years and years getting their legs strong and serious enough to ride fast, I have it already, and don't have to work too hard to keep it on.

but how and why should I have more torque at the end of my stroke with length alone than a sprinter or body builder does?.

Maybe the reasons the 21 and 24 speeds work for me is because I am coming away from my prime

badger1

I love Bike Forums. One couldn't write this stuff if one tried. Kudos!

FBinNY 

+1 quality fiction is so rare these days.

Seriously, anyone who cares about this needs to consider it in the light of Newton's 3rd law of motion.

Mechanical systems can be examined by looking at either the input or output side, which according to the 3rd law, are equal.

So, looking at the input side, it's a question of the rider's strength and the leverage advantage gained by gearing. Meanwhile, the output side has a limit, based on what would cause a wheelie (anybody who's seen a drag race knows this). In turn, the wheelie limit depends on weight and height of the center of gravity. (more precisely the angle of the line from the CoG to the rear wheel's point of contact, but let's not quibble)

So, a thoughtful analysis will show that strength isn't the key issue, since gearing can compensate for that, and the real limiting issue that determines the maximum stress on a bike turns out to be weight, which shouldn't surprise anyone.

Currmudge

Why did you replace the chain? Worn out? Guess what -- GEARS wear out at the same rate.

ALWAYS replace chain/cassette together when worn.

Strength/power/torque/freakish output....LOL.

Buncha suckas. Sound like you all shop at Walmart.

wphamilton

Usually, three chains per cassette, sometimes four.

TreyWestgate

If you looked at the start of the thread you will see that it says that I replaced the chain and cassette, but I still had a problem with slipping in the chainring.

Now maybe I should have pursued changing the chainrings as well, but the bike shop mechanic said that they looked fine.

On a geared bike it could be any number of things that caused problems.

Maybe the derailleur was not taking enough slack out of the chain. I don't know.

That's a plus with single speeds, if something is going wrong, it's easier to narrow it down.

it's was a good bike in every other way, but you can't ride a bike that won't let you. every stroke was a pop and slip.

and I also mentioned how this occurred with new bikes for a time as well.

So it very well might have been my leverage and torque due to my long legs.

TreyWestgate

and I agree with the output as well as input.

A 29er wheeled bike is always going to be geared higher than a smaller wheeled bike because of the wheels.

Bigger wheels need shorter gearing.

Smaller wheels need steeper.

32:21 is not wimpy when it comes to 29 wheels

wphamilton

Just setting the record straight on "gears wear out at the same rate".

I don't think that longer legs give any advantage in leverage and torque. I'd look elsewhere for the culprit.

Currmudge

My experience says otherwise; evidently, I put more stress on parts than you do.

FBinNY 

Once properly engaged on a sprocket a chain will snap before it slips. That requires a staggering amount of force.

Don't delude yourself about superhuman strength, and look for the problem someplace within the drive train.

You started this thread asking whether it's possible to be too strong, and a number of experienced people have told you no, and tried to show you why not. You keep coming back to this erroneous premise, and until you let it go, you won't find the actual cause of your problem.

In my case, having tried to set you on course, I find further effort pointless, and bid you adieu.

wphamilton

I doubt that's it, but there are other explanations for premature wear on the cassette so it's possible that you do need to change your cassette every time you change a chain. Most people with properly maintained bikes, with normal shifting habits, don't.

GamblerGORD53

Get a Rohloff14 bike. Problem solved.

CliffordK

Oh, I can do the accidental wheelies.

Actually, climbing about a 17% slope, the equation is complex.

Too much weight in the back, and the front wheel pops up (sitting on seat)
Too much weight forward, and I lose traction when wet (standing).

A long or short wheelbase & bar location can also throw off the wheelie/traction equation.

While my average power is likely below 500W, the peak power/torque on the power strokes is likely much higher.

Some things that can improve at least the torque profile is higher cadence, and more of a round pedal stroke.

I suppose the argument is that the accidental wheelies does limit torque, but only with steep hills, and one can adjust weight (on dry pavement) to limit the possibility.

digibud

Sprinters have their Di2 gear button right at their thumb because as they get ready to change gears they don't have to make any motion. The point being...they change gears ... and put on their pants one leg at a time. While I'm aware that top pro sprinters do crazy crazy watts...they don't put the bike in it's hardest gear while riding along, chatting with a friend and then say, "I'm going to sprint for a minute" and slip into the hardest gear possible, stand and torque the !@#$ out of the bike. THAT kind of thing is what a 6' 5", massive beast does when they don't have any cycling technique. Cav may be all sorts of strong but a 6' 5" beast CAN'T be a pro cyclist...so does it make sense that there are plenty of huge, strong cyclists that are clueless with regard to technique that can destroy a bike and rip apart chains? Makes sense to me. After learning some technique, the same "masher" that destroys bikes could easily learn to ride proficiently and keep his drivetrain happy...

Phil_gretz

Nonsense upon nonsense. OP's problem is that his mechanic isn't any good. Visual inspection isn't the method to disprove whether chainring wear is the contributor. Changing to a new chainring to match the chain and cassette is the correct course of action. OP - get a new mechanic...and a new chainring. Problem solved.


Too much torque or power? HAH!