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 Post subject: Granny gears are a drug
PostPosted: Sat Jan 18, 2014 11:23 pm 
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This winter I got a cross-country bike with disc brakes so I can go downhill in wet conditions more confidently. Also learn to mountain bike. Also ride with my kid at his pace. The bike has granny gears. I figured 20 pounds or so more weight, wide knobby tires, makes sense to use granny gears on some road climbs. Getting on my road bike after weeks of riding just the cross-country bike, including rides with road hill repeats, I was disappointed that I was slower than before, and needed to use lower gears on climbs. My conclusion is that when I'm riding the cross-country bike, I shouldn't overcompensate for the increased weight and rolling resistance with downshifts.

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 Post subject: Granny gears are a drug
Posted: Sat Jan 18, 2014 11:23 pm 


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PostPosted: Wed Jan 29, 2014 3:51 am 
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You're over thinking it. If you have the gears, use them. Climbing cadence is a personal thing but you shouldn't be below 80rpm really. You're slower and need more gears because you didn't train as hard during the winter, so it'll take a bit to get your fitness back up.


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 Post subject: Granny gears are a drug
PostPosted: Wed Jan 29, 2014 5:41 am 
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Joined: Sat Jun 19, 2010 8:21 pm
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Location: Zürich, Switzerland
I had the same experience when I tried on a compact 50/34.

While it is true what russianbear says, that gear inches are gear inches no matter the gearing you have, the fact you have lower gearing leads you to use them and gradually lower your effort and go overall slower.

It's all on the head, not on the gearing....

And probably many will say they didn't experienced that, but well it was like that for me...

I did setup back the standard and my fitness went gradually back to "normal"

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PostPosted: Wed Jan 29, 2014 10:42 pm 
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I tend to agree. Climbing is so inherently painful that I just tend to keep downshifting until I am out of gears.
Then, I noticed that if I just don't take the low gears with me, the times and powers are actually better.
Higher cadence feels more efficient, but the data shows that bigger gears are faster.

But I still ride very low gears because I suffer from the delusion that I can train my spin until it is more powerfull at higher cadence.
It just hasn't happened yet. :D


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PostPosted: Wed Jan 29, 2014 11:53 pm 
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Absolutely.
I just grip the tops as hard as I can, to resist the temptation of downshifting. It works.


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PostPosted: Thu Jan 30, 2014 10:52 am 
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With addiction you need to replace a drug with another drug. Get a single speed. It's a whole other very different experience.

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PostPosted: Thu Jan 30, 2014 11:12 am 
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efeballi wrote:
I just grip the tops as hard as I can

I read this every now and then, and don't get it. I never really pull on the handlebars, not even when doing uphill intervals, unless it's very steep, say over 12%.
Maybe you should tweak your position, being relaxed in the upper body lets you breathe easier, so you can go faster.

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PostPosted: Thu Jan 30, 2014 8:35 pm 
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I hear the "pull" and "don't pull" recommendations all the time.

But at some point of steepness/cadance you are either pulling or you are pushing your ass off the seat, so you must pull. And it sems like, by comparison to other people going as fast or faster, the really fast people must be pulling too. It seems like a necessity of physics that to climb well and fast, even at "high cadance" you must pull on the bars a bit.

But I am open to conflicting opinions of technique.


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PostPosted: Thu Jan 30, 2014 8:53 pm 
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Gripping and pulling are not the same thing. I found that I squeeze the handlebars when on the rivet, and that helps me somehow.
Rick, that is about the pedalling forces pushing you behind the seat. You need to either lean further forward (what I do) or pull yourself toward the bars.
Or, you can climb at a high cadence and forget about all this.


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PostPosted: Fri Jan 31, 2014 12:40 pm 
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taina wrote:
My conclusion is that when I'm riding the cross-country bike, I shouldn't overcompensate for the increased weight and rolling resistance with downshifts.
I see this a lot, mtbers decide that the best way to climb is with the lowest ratio available on the bike, rather than the lowest ratio it's possible to climb the gradient with. Just leads to going up hills really slowly, with virtually no training benefit.

Then they wonder why they aren't getting fit, despite spending mammy hours in the saddle.


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PostPosted: Fri Jan 31, 2014 3:15 pm 
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But mtn bikes have an additional consideration: traction.

If you are stomping a big gear up a steep hill on a mtn bike it is very common to break traction. Spinning a low gear helps maintain constant traction. So it is really a slightly different thing.


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PostPosted: Fri Jan 31, 2014 3:21 pm 
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I want to say it's the opposite? Lower gear = more torque = more slippage? Try doing a burnout in your car in 3rd gear.


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PostPosted: Fri Jan 31, 2014 3:33 pm 
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If two riders are climbing a hill next to each other at the same speed, one in higher, one in lower gear, the force between tyre and ground will be the same.

Agreed that it's easier to recover from a slippage, though, when you're not running the highest gear possible, because obviously you slow down, and that might be too much to keep going with the hard gear.

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PostPosted: Fri Jan 31, 2014 8:03 pm 
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The talk of MTB traction is certainly getting a little off topic, but I can't resist, as this is something I have put a fair bit of thought into myself.

Over the years, most of the "pro" tips I have seen concerning climbing traction support what kulivontot said. Basically, this can be summed up as "run a gear or 2 higher than normal when traction is bad, as the reduced torque will reduce the chance of breaking the tire loose". There is no denying that higher gears will lower peak torque, and this, in theory at least, will reduce your ability to break the tire free.

At the same time, wassertreter makes a very good point that if you do spin the tire, being in a higher gear will make it harder to recover and keep pedaling. If a higher gear manages to prevent the spin in the first place, then the point is somewhat moot, but higher gears, at best, reduce spins, so this is certainly worth considering.

wassertreter also makes a point about equivalent speed between two riders equaling equivalent force being transmitted through the tire contact patch, and this is certainly true when taken as an average.

The additional element that I think should be considered though, is that power is not delivered at a consistent average rate. it is delivered as a series of pulses, resulting from each pedal downstroke. A lower gear will result in a greater number of short duration pulses to get up a given hill, when compared to a higher gear, which will require fewer, and longer duration pulses.

This is where I think things get so puzzling, as individual rider technique comes into play. It is not so much the frequency and duration of pulses that would effect traction, as it is the peak force during each of those pulses. Specifically, minimizing the peaks, although if speed is to be maintained, that same power will need to be redistributed to other parts of the pedal stroke. So, in other words, the gear that allows you to deliver power most smoothly will be the one that delivers the most reliable traction, and that is where individual variation comes into play.

Rick mentioned an example above where "stomping" a big gear causes a loss of traction whereas "spinning" a low gear maintains traction. I would suggest that this is not purely an issue of gearing but of "stomping vs. spinning", and that some riders may find that a slightly higher gear actually smooths power delivers, vs. a low gear where instead of spinning they may in fact end up with a "choppy" pedal stroke, whereas others may find the reverse.

Additional factors are how body position is affected by gearing choice. Some riders might compromise upper body form more in order to push a bigger gear than others and, conversely, others may have trouble controlling their movements precisely at a high cadence. Also, it is worth considering the trail conditions. Everything above assumes consistently low traction, but some trails may be a series of slippery roots or bits of loose gravel, separated by areas of good traction. In those situations, the gear that best allows you to time your power pulses to hit the good traction will be best, regardless.

Without a peak torque analysis of a given rider, I think that it would be difficult to make individual prescriptions.


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PostPosted: Fri Jan 31, 2014 8:51 pm 
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The theoretical controversy is easily resolved by actually riding a mtn bike. It becomes obvious pretty quickly.


---at least I think its pretty obvious. If there are any mountain bikers with experience climbing steep dirt trails who disagree, they can weigh in.
I am talking about small-triple-ring-big cog steep.

EDIT:
Thinking about it some more: I can see that in theory, any combination of cadence would be possible.
One could use an extremely high gear and then control one's pedal force such that the torque at the rear wheel was always just sub-break-free".
But I think most people are able to produce less pedal force as pedal velocity (cadence) increases. So if you gear low enough, you are "self restricted" from breaking free. Whereas if you are just "consciously controlling your pedal force" then you have to sense the break-free and immediately back off a little, then increase the force again as traction is re-established; requiring more complex feedback control. Maybe some people are just much more neuromuscularly adept at that kind of control.

But we are getting off the original topic. My point was only that mountain bikes have an additional variable of "traction" that road bikers usually don't need to consider.


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Posted: Fri Jan 31, 2014 8:51 pm 


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