How do I work out how much to increase stem length?

[NicoBoshoff]

The problem I see here is a lot of people may very well have rode with too naroow bars FOR THEM.  Ergo "wider is better".

 

It's anecdotal evidence being sold as a golden rule.

[NicoBoshoff]

extra pedaling leverage with wider bars .......LOL

 

 

Ok well I guess pulling at an extreme angle is much more efficient than pulling in a straight line.

Let me go and design a new fangled triangular block and tackle

Look I just chatted to my cousin who's an engineer and as he explained it there are two considerations here.  Steering force may be theoretically improved because you excerting a greater "turning/bending (sorry I am translating from Afrikaans) moment" on the center of rotation.  But that will impact on your ability to steer the bike with the same forces across the spectrum of widths.

 

HOWEVER, the question is how efficient the human arm is the further away from your torso.  Take it to the logical extreme.  A 1m bar.  How efficient will that pedal?  How much force can you excert on that turning centre?

 

And that's the point.  WIDER IS NOT ALWAYS BETTER.  It is only better when it will be better for that specific bike and body.

[GoLefty!!]

Look I just chatted to my cousin who's an engineer and as he explained it there are two considerations here.  Steering force may be theoretically improved because you excerting a greater "turning/bending (sorry I am translating from Afrikaans) moment" on the center of rotation.  But that will impact on your ability to steer the bike with the same forces across the spectrum of widths.

 

HOWEVER, the question is how efficient the human arm is the further away from your torso.  Take it to the logical extreme.  A 1m bar.  How efficient will that pedal?  How much force can you excert on that turning centre?

 

And that's the point.  WIDER IS NOT ALWAYS BETTER.  It is only better when it will be better for that specific bike and body.

 

 

exactly!

[NicoBoshoff]

exactly!

So as GoLefty! said, yes, a longer arm (handlebar) will excert greater moment  ASSUMING the force initiating the moment is being excerted at a 90' angle.  Too wide and the angle diminishes.  The force diminishes.  You're failing.

[Capricorn]

 

Me personally I was amazed at the extra pedalling leverage I gained with wider bars, PEDALLING UP HILLS, unexpected and very welcome benefit.

 

 

 

You are right as that is what you experienced, but the cause is somewhat misphrased: a wider bar takes you slightly more forward. I'll bet you had to lean over or scoot forward on your saddle a bit.

This is similar to making the seat-tube angle steeper,which is great for pedalling uphill. I believe this is why wider bars made pedalling uphill feel easier: more forward position.

 

I might have missed this in the previous posts, but remind me: what type of riding does the OP want to do the best?

[GoLefty!!]

You are right as that is what you experienced, but the cause is somewhat misphrased: a wider bar takes you slightly more forward. I'll bet you had to lean over or scoot forward on your saddle a bit.

This is similar to making the seat-tube angle steeper,which is great for pedalling uphill. I believe this is why wider bars made pedalling uphill feel easier: more forward position.

 

I might have missed this in the previous posts, but remind me: what type of riding does the OP want to do the best?

 

 

 

barein mind the bike in question a XC race hardtail with a head tube angle of 72 degrees I'm not seeing a short stem being a good answer.

OP's never posted a pic of the bike nor a selfie with himself on it.

[Nayr]

Fact is, top tubes are getting longer and stems are getting shorter on bikes out the box. I have to say that I personally agree with this thinking, fwd geometry, if thats what your prefer, should come from the frame. Look at the new Yeti ASRC as an example of this. They've designed an XC bike that can be pedaled efficiently, but point it downhill and it behaves like a trail bike. After all we are talking about mountain bikes here, there has to be some form of compromise because we theoretically need to do everything on the same bike. Fact is, the longer the stem the more indirect the steering, which ultimately means less confidence and thats fine if you ride straight lines all day, but then you're not really mountain biking. So if you have to go with a long stem to ensure the right fit, then possibly you're on the wrong size frame or bike for that matter. All I know is that I want to be as confident as possible when the trail gets tight on my xc/xcm bike.

 

But to answer the OP again, the reason your hands are going numb is your applying to much pressure on them...simple. So the theory of going with a shorter stem or a rise on the bar is correct because it will sit you more upright on the bike which will mean you're not leaning on the bars as much, but being as tall as you are this may compromise your peddling efficiency. It seems like you do need wider bars so you are not as cramped, but without a shorter stem, they will pull you more fwd on your bike and possibly increase the pressure on your hands. Manufacturers don't design bikes around guys your size, so you are going to have to find a compromise somewhere. Without changing your frame, my advice would be to get as comfortable on the bike as you possibly can be, stacks, bars, stem, seat post etc. without compromising peddling too much.. and then do some serious core strengthening...

[Capricorn]

Nayr hits on a very important aspect of this whole debate: the frame vs intended usage. XC bikes were designed for pedalling efficiency, and in my opinion, without consideration for hardcore descending as evidenced by the lightweight construction and lack of additional reinforcing.

 

The concept of enduro has placed a double constraint upon frame designers: make the bike strong enough and stable enough to descend, but sufficiently capable of being pedalled uphill. This is where forward geometry has taken the limelight of posterchild for bikes with short chainstays easier maneuvrability, steep seat angles for better climbing ability, but longer front ends to ensure sufficient bike length for stability at high speed as well as ensuring suffficient REACH (important!) to provide the rider with sufficient cockpit space, very slack headangles for hardcore descending capability, but modified fork offsets to accomodate for the lack of steering control with very slack head angles.

 

This all makes for a bike thats maybe not as heavy as a DH bike, but not as light as an XC bike. Its definitely as strong as a DH bike, but way stronger than an XC bike. there are a bunch of trade offs compared to each of those polar opposite rider paradigms, which makes this discussion abit tricky as the advice needs to be qualified with what type of riding you have in mind at the time.

[popcorn_skollie]

I'm not trying to justify my suggestion of a shorter stem wider bar sollution on OP's bike by the standards of a more gravity orientated bike. The likeness of associated forward geometry, my prefered kind of bike and my suggestion is purely coincidental.

At some point, he is going to point that bike down.

A rider his size, slouched over the bar on a bike with a 72 ha is a recipe for a ride that is sure to unnerve or worse. Thats it.

Not the handling benefits, not the new trends of bike geometry, and not the enduro bandwagon.

Just looking out for OP. Trying to pass off my 2 cents as common sense.

[Capricorn]

I'm not trying to justify my suggestion of a shorter stem wider bar sollution on OP's bike by the standards of a more gravity orientated bike. The likeness of associated forward geometry, my prefered kind of bike and my suggestion is purely coincidental.

At some point, he is going to point that bike down.

A rider his size, slouched over the bar on a bike with a 72 ha is a recipe for a ride that is sure to unnerve or worse. Thats it.

Not the handling benefits, not the new trends of bike geometry, and not the enduro bandwagon.

Just looking out for OP. Trying to pass off my 2 cents as common sense

 

All probably true, but context is important, and the wider bars shorter stems story has a basis which is important to be aware of so as to understand what can be achieved by making a change. All about making an informed decision, but hopefully with the facts of the matter.

[Skylark]

You are right as that is what you experienced, but the cause is somewhat misphrased: a wider bar takes you slightly more forward. I'll bet you had to lean over or scoot forward on your saddle a bit.

This is similar to making the seat-tube angle steeper,which is great for pedalling uphill. I believe this is why wider bars made pedalling uphill feel easier: more forward position.

 

I might have missed this in the previous posts, but remind me: what type of riding does the OP want to do the best?

Ok that sounds reasonable but bar width in of itself must have some kind of bearing on the effective leverage you experience at the pedals?

[NicoBoshoff]

Ok that sounds reasonable but bar width in of itself must have some kind of bearing on the effective leverage you experience at the pedals?

Absolutely, but your shoulders/arms don't grow with bar width.  So there are limits at which point it becomes useless since you can't excert the force needed to get the benefit of the leverage. 

 

It's rider specific i.e. no golden rule.  680mm bars may be perfect for some.

 

It's no use trying to jack up a car with a truck jack but standing at an angle to the jack's lever...

[Skylark]

Absolutely, but your shoulders/arms don't grow with bar width. So there are limits at which point it becomes useless since you can't excert the force needed to get the benefit of the leverage.

 

It's rider specific i.e. no golden rule. 680mm bars may be perfect for some.

 

It's no use trying to jack up a car with a truck jack but standing at an angle to the jack's lever...

First you and lefty say that wider bars has no effect on a riders effective pedalling leverage now you say it absolutely does, so basically you guys are just saying whatever bs suits you at the time?

[Capricorn]

Ok that sounds reasonable but bar width in of itself must have some kind of bearing on the effective leverage you experience at the pedals?

 

leverage on the cranks is determined by the length of the cranks themselves, including the length of your femur for seated pedalling. The only motive force acting on the pedals is muscular

For standing pedaling, its length strength + body weight.

 

So the question is, how does bar width affect these sources of motive force? For standing pedalling, not much I believe. it may move your center of mass to the point that it changes where in the rotation the crank, you start a pedal stroke. That's a case for efficiency, not leverage.

 

For seated pedalling however, it can affect which muscle groups are relied upon to drive the cranks. So narrower bars might push some riders further back on their saddle, while wider bars might force the driver to come further forward. It changes the pedaling efficiency due to changes in which muscles are engaged.

 

So in a nutshell, the wider bars may just have changed your riding position to one that's more effective at pedalling than before. Bar length doesn't change your mass, femur length, or crank arm length.

[NicoBoshoff]

First you and lefty say that wider bars has no effect on a riders effective pedalling leverage now you say it absolutely does, so basically you guys are just saying whatever bs suits you at the time?

Really? 

 

I said that bar width does not equate to pedalling efficiency simply because of more leverage.  So yes, more leverage in theory, but not necessarily more efficiency (i.e. usage of that leverage). 

 

Leverage in a vacuum supposes perfectly angled forces being imposed on the point of leverage. 

 

Riding a bike is not such vacuum.  So wider isn't always going to be more efficient for pedalling because that leverage won't mean jack if it's the input angles are stupid.

 

But cool story bro.

[Skylark]

Really?

 

I said that bar width does not equate to pedalling efficiency simply because of more leverage. So yes, more leverage in theory, but not necessarily more efficiency (i.e. usage of that leverage).

 

Leverage in a vacuum supposes perfectly angled forces being imposed on the point of leverage.

 

Riding a bike is not such vacuum. So wider isn't always going to be more efficient for pedalling because that leverage won't mean jack if it's the input angles are stupid.

 

But cool story bro.

Ok great, explain how you came to the conclusion that my experience of using wider bars and them helping me with my effective pedal leverage was incorrect?

 

Am I correct to assume you don't know what width bars I had before, what width bars I went up to nor my body dimensions or fitness?