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Spinning bike cranks


The Pink Mouse
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Is it possible to bend the cranks on a spinning bike if so how ?

not necessary to break the bike , just stop spinning!!  :w00t:

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I am asking as I was told that by standing on both peddles the cranks get bent, so want to know if anyone else has had experiences of cranks bending in a gym and why.

I have ridden bics more than half my life from spinning bikes, road and mountain bikes, never heard of cranks bending because of standing up or how one climbs onto it.

I feel they then have cheap cranks in or someone over 200kg on the bike. Don't see that a 65 kg person could bend cranks.

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Spinning bikes generally have weight limits. Home use is generally around the 120kg - 150kg mark, and commercial use would be slightly higher. These can vary from manufacture-to-manufacture.

In terms of the cranks bending, when used properly and within the weight limit of the equipment. Shouldn't bend.

I have a mate that bought a cheap spinning bike from Game I believe, in order to lose weight. His starting weight was 105kgs. He has been using his spinning bike for close to a year (bought before lockdown). No issues.

At 65kg, I can't imagine you would bend cranks by standing.

I am curious to know, who told you that?

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I am a spinning instructor at a gym, I have a spinning bike at home & have had it for at least 10 years + now.

No issues with mine either not cheap bikes but not top of the range.

Been riding bicycles for over 30 years & husband for over 50 and all our equipment is still 100 %.

So was just for interest sake wanted to find out how it would be possible to bend cranks.

 

I was told by the gym manager, not to climb on the bike with one peddle but to sit on it and then put your feet in or go back over the saddle with heels down to stretch the calves as by standing on the peddles the crankes will bend as they have had problems in other gyms.

I can only think either the weight was over the bikes limit and they were doing some sort of hip hop on the bike or they have very cheap cranks on. ‍♀

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If you have a spinning bike and Mark Cav decides to do some sprint intervals, the force he puts down will be 10 times that of an 80 kg medium build Joe Soap standing on the pedals/cranks. Do we ban interval training on spinning bikes now. I am calling BS on the claim you can bend cranks by standing on the pedals (or even standing on the cranks). Basic moments of inertia.

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Thanks LongDonkey, it's been baffling me.

Yes a friend of our has all 5 track titles a very big man & I believe he has bent cranks but not the axle.

 

Maybe they referring to the axle but even then, the only way to bend the axle is if they are cheap rubbish or by dropping the bike or doing something stupid & the person is 200 + kilograms doing some really hectic hip hop moves. ‍

 

I checked the bikes limits and they can take up to 180kg

These bikes are not cheap, something in the region of $4,500

Being commercial bikes they should be able to withstand a bit more punishment than the Game home spinners.

Edited by The Pink Mouse
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I have had the same spinning bike (Raliegh ) for more than 30 years . At times during my off bike years i would start riding it at 125 kg . Im a serious spinner on my spin bike and vary my riding to spinning at 120 rpm to pushing hard against resistance at 60rpm . Never have i felt that these cranks would bend or give me a bottom bracket problem . I serviced regularly and the only consumable i replaced was the chain which had stretched and was jumping the front chaining. Without photos this claim is BS.  . 

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I have had the same spinning bike (Raliegh ) for more than 30 years . At times during my off bike years i would start riding it at 125 kg . Im a serious spinner on my spin bike and vary my riding to spinning at 120 rpm to pushing hard against resistance at 60rpm . Never have i felt that these cranks would bend or give me a bottom bracket problem . I serviced regularly and the only consumable i replaced was the chain which had stretched and was jumping the front chaining. Without photos this claim is BS.  .

 

I don't have any pictures. I was told this by the gym management, that certain excersises, we are not allowed to do, as it will bend the cranks.

So just wanted to know if anyone else had this experience.

As I thought it rather a strange claim.

 

My first road bike is an antique & had been through a few crashes never ever any problems with it, apart from the chain.

My spinning bike at home not top of the range, no problems there either.

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as Mr Donkey said, honking out the saddle is effectively standing with full weight on one pedal. Mr Gym Manager is telling a bunch of porkies here

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Mmmm .. There is a huge difference in built quality between a 2K Makro special and a commercial studio indoor machine.

 

On one occasion I accidentally bent a friend’s indoor cycle crank-arms' too, or maybe it was the pedal axles? That feeling when the pedals start angling inwards when at 12 0’clock.

 

When grinding at full tilt, moving the resistance to “max”, and turning of the crank only being possible by pulling and pushing simultaneously the force is much greater than just standing on the cranks.

 

Many of the 30-year-old machines were over engineered, and would last longer, the current cheap Chinese/Makro imported trainers is really just for spinning only, once you start grinding - multiple parts starts failing.

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as Mr Donkey said, honking out the saddle is effectively standing with full weight on one pedal. Mr Gym Manager is telling a bunch of porkies here

My thoughts exactly !!!

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I am a spinning instructor at a gym, I have a spinning bike at home & have had it for at least 10 years + now.

No issues with mine either not cheap bikes but not top of the range.

Been riding bicycles for over 30 years & husband for over 50 and all our equipment is still 100 %.

So was just for interest sake wanted to find out how it would be possible to bend cranks.

 

I was told by the gym manager, not to climb on the bike with one peddle but to sit on it and then put your feet in or go back over the saddle with heels down to stretch the calves as by standing on the peddles the crankes will bend as they have had problems in other gyms.

I can only think either the weight was over the bikes limit and they were doing some sort of hip hop on the bike or they have very cheap cranks on. ‍♀

I have been told some, let’s call ‘interesting’ things by gym staff in the past. I wouldn’t take it at face value.

 

You mentioned you are a spinning instructor. If the movements described is detriment to you offering a class. My suggestion would; see which manufacture make the bike, and speak to one of their technical advisors.

 

They should be able to give you all the necessary information. You could potentially educate the gym manager.

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Mmmm .. There is a huge difference in built quality between a 2K Makro special and a commercial studio indoor machine.

 

On one occasion I accidentally bent a friend’s indoor cycle crank-arms' too, or maybe it was the pedal axles? That feeling when the pedals start angling inwards when at 12 0’clock.

 

When grinding at full tilt, moving the resistance to “max”, and turning of the crank only being possible by pulling and pushing simultaneously the force is much greater than just standing on the cranks.

 

Many of the 30-year-old machines were over engineered, and would last longer, the current cheap Chinese/Makro imported trainers is really just for spinning only, once you start grinding - multiple parts starts failing.

 

OOPS!

These are not cheap trainers, in the region of around R30-40,000

Yes the only way I can possibly see any bending happening, maybe is as you say with a very strong Sprint Champion on the bike with the resistance on full blast & grinding full steam ahead.

Don't see that a 65-90 kg person not cyclists, so they will be on very light resistance by standing on the peddles will bend anything.

 

I went on the road this week on my mountain bike and coming down a hill at 70km I happened to go through a huge pothole which I saw too late, had to make the choice of fly or end up in the bushes.

I decided to fly and yes standing on the peddles through the pothole, fortunately all good and no bending of anything. Haha !

Edited by The Pink Mouse
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