8bitevolution

I paid off and picked up my first bike yesterday - a Trek 7300. My previous bike experience is limited to an old BMX I had growing up and riding my dad's mountain bike a couple of times. So I have to be honest - gears confuse me.

I'm used to the way cars work - low gears produce more power output per revolution, and the higher gears are used to maintain speed without working the engine as much. I assumed this is how a bike's gearing would work.

After riding around my neighborhood for a bit, my legs were pretty well burning. I did some research and found out three things I was doing wrong - my seat was too low, my feet were in the wrong position, and I don't think I was using my gearing even remotely right.

I'm working to correct my foot placement - ball of the foot over the axle of the bike pedals, correct?

I still think my seat height needs a tad bit of adjustment. My leg is not all the way straight at the bottom of my downstroke. It should be, correct?

And finally gearing. I scanned some articles but a lot of them went way more technical then I would like. First, a lower gear essentially is made up of the smaller gears of the chainwheel, correct? So your smallest gear on the chainwheel and rear tire would be your lowest gear and the biggest gear on your chainwheel and rear tire is the highest, correct?

Second, when riding on flatland, should I be using a middle gear or lower gear or what? A low gear usually feels like I'm pedaling too much and getting no power. A higher gear gives good power but I feel like I'm wearing myself out rather quickly. I've read that when coming up on hills, it's better to switch to a lower gear and lose speed but maintain the same pedaling speed (cadence). Is this true? What's the benefit to maintaining a consistent cadence?

Should my legs be burning after a 10 or 15 minute ride without too many hills due to a lack of exercise or am I just riding my bike all wrong? As I said, the seat height and pedal thing I know I was doing wrong so I can only assume I'm getting gearing all wrong, too. If this is due to a lack of exercise, how often should I be riding? Is there anything I need to do to help rebuild muscle after riding?

I know this is a lot to ask but I'd really appreciate any help or advice. Thanks again.

-Sean

HiYoSilver

Nope,
Lowest == smallest chainring [front] x largest cassette ring [rear]
Highest == largest chainring x smallest cassette


You just got your bike. On flatland you should keep the front on the middle ring and change the rear up or down to adjust whether it's too hard or too easy for you

Depends on the length of the hill, some steep hills when have low energy will gear down to lower easier gear before starting up because know it will cost me more effor if wait to switch part way up the hill when I'm wasted.

You always want to be about the same cadence, at least when starting out. You'll probably be in the 70 to 80 rpm range. You don't want to drop below 70 and don't want to go above 110. Later you can work on improving cadence. Benefit of constant cadence is you're using slow twitch muscles which go and go and go. If you power with pushing, fast twitch muscles, you get more force but they are like turbo's and can only fire so long before they need a rest.


No, you're pushing it too much. You don't want to create an injury that will take a long time to recover from. Expect not to feel great riding until you have at least 500 miles under your belt. First get your positioning fixed. Have the store you bought it at double check it's fit. It sounds like it may be a little off. Oh, old days, proper height of saddle was so leg was fully extended on down stroke. Now it's almost extended but never extended.

8bitevolution

I feel silly asking, but how do I pedal without pushing? I mean, if you're not pushing the pedals with your feet, then how?

roughrider504

You still push, but not hard. once you find the perfect gear for your terrain, espically on road, you can barely pedal and keep up speed.

jimmuter

Probably, although I like to move my feet around a little until I feel comfortable.


I could be wrong, but I think your knee should still be slightly bent at the bottom of the downstroke. It could damage your knees if you're locking your leg each revolution.



Take it easy the first few times out. As far as your muscles, the Bicycling magazine I got yesterday had something about this very topic. To summarize, they recommend plenty of protein in your diet, eating lots of fruits and veggies which have anti-oxidents that fight free radicals, and most importantly, refuel immediately after riding by eating some carbs. Don't get discouraged. You got a great bike and you will get the feel of it after a few times out. Enjoy your new bike.

Nermal

Oh, on the seat height question. No, you don't want your leg to be completely straight at the bottom. You want a small amount of knee flex, so your seat is probably about right.

You didn't ask, but just btw, the seat post should have a mark that shows when you are getting above the safe (mechanically) height. To exceed this limit, you would probably have to be a very tall person on a small frame bike, but you might take a look.

tippy

You can change the force required to pedal by selecting the appropriate gearing.

Power has two main variables: RPM and FORCE. The final result of power output is the speed you are moving down the road (power out verses resistance). So the power it takes to move your bike at 10mph can be made doing High RPMs with minimal force OR low RPMs with elevated force. Either way, as long as you are maintaining 10mph, power out is still the same.

Good Luck,
d.tipton

cc_rider

You can get very techincal in your gear choices.
I like to keep it simple - use whatever gear is comfortable while keeping a fast cadance. If there is too much resistance, I shift to the next easiest gear. Too little resistance I shift to the next hardest, until I run out of gears. I shift the rear gears until I start putting too much an angle on the chain, then I shift the front chainring.
If I'm coming up on a big hill, I use the advise you heard about, I shift just before I need to so I can maintain the cadance.

With practice you'll get the feel of how your body works best on your bike.

Toeclips or clipless pedals will help keep you feet in the right place.

edp773

No! A good starting point is to set your seat height so that your leg is straight at the bottom of your downstroke wth your heal on the pedal. You can check this adjustment while sitting on your bike. Then when you pedal with the axle under the ball of your foot, your knee will have enough bend to prevent injury.

BlazingPedals

On a bike, the gear is determined by the ratio of chainring teeth / freehub teeth. So the lowest gears are in the small chainring in front and the largest cog in back. There is a fair amount of overlap between rings, so it's best to think of the chainrings as being 3 ranges of gears - underdrive, normal, and overdrive.

For beginners on relatively flat terrain, it is simpler to use the middle chainring and change gears by using only the rear derailleur. Once that comes naturally, then you can expand your repertoire and add in the other rings. Try to ride with a pedal cadence of at least 80-90 rpm - that's around 3 foot strokes per second, L-R-L. Doing that will be easier on your knees and quads.

huhenio

Or perhaps you want a one gear bike ... many of us put a lot of miles in them

AndrewP

If you find you are pedaling with your instep over the pedal, get a pair of toe clips to stop your foot moving forward. You dont need to bother with the straps. When you are used to the correct foot position, you may want to switch to pedals that latch onto the bottom of your shoes (clipless), but that is a big investment in both shoes and pedals. Try pushing the pedals all the way around the circle not just at the 3 o'clock 9 o'clock position.
With your seat at correct height and your toes on the pedals, you may have trouble reaching the ground when you stop. There is no harm in moving forward off your saddle when you stop, putting one foot on the ground. Then move your other foot with the other pedal to the 2 o'clock position ready to move of and get you up onto the saddle again.

DannoXYZ 

I think everyone pretty much covered it. Just a minor physics clarification...


Power-output is actually the same regardless of gear. It's the torque that changes with gearing. So if you're cruising down the freeway 65mph in 5th gear @2500rpm, you'll need about 20hp. You can also use 4th gear @3500rpm to also generate 20hp, but you'll notice that the throttle-opening is smaller. The 4th gear spins faster, you get more combustion pulses per second, so each pulse can be smaller to generate the same power-output.

The way that works on a bike is you can be cruising at 20mph in a gear that requires 75rpm. This requires a certain amount of force on teh pedals. You can also select a lower gear, so that 20mph requires 90rpms. The muscle-force needed on the pedals will only be 80% as much as before.


Burning legs are caused by lactic acid. This is due to anaerobic fermentation in your muscles due to high-effort. It's inefficient and requries a lot more oxygen to clear out and causes muscle soreness as well. The LT-lactate threshold is the exertion level where your muscles transitions between efficient aerobic operation into inefficient anaerobic mode. Stay below this exertion level by using lower gears and spinning your legs faster. Same power-output and speed, but you can push on the pedals lighter. This extends the distance you can ride before you have to stop due to muscle-fatigue.

HiYoSilver

I don't quite understand the physics. Please expand your explanation. This is a very very interesting concept.

If power is the same, and speed is the same, just how is muscle force lower?

8bitevolution

Thanks for all the advice! I'm going to try and measure my cadence fairly soon so I can get a feel for if I should be pedaling faster (which I'm sure I should be).

When I took my bike out Sunday, I noticed immediately that the saddle just doesn't feel comfortable and I plan on switching it out; I noticed a lot of people saying that about the Trek 7000 series. After my ride, there wasn't really any burn in my legs but a little bit of soreness, probably from the day before. My legs are a little stiff today but overall feel pretty good so we'll see how tonight's ride treats me.

Once again, thanks for all the advice and I'll try to apply it in my riding.

MacG

Imagine lifting 200 pounds of bricks in a bucket using rope and pulleys. You could use a simple pulley setup with just one pulley at the top, and you would have to pull down with 200 pounds of force on the rope.

If you used a block and tackle setup, where the rope makes multiple passes from the upper pulleys to the bucket, you don't have to pull as hard on the rope to move the bucket, but you have to pull more length of rope to get the same movement of bucket.

Pulling 40 feet of rope with 100 pounds of force is considerably easier than pulling 20 feet of rope with 200 pounds of force. The important thing to note is that regardless of what solution you utilize, you still end up lifting 200 pounds of bricks 20 feet.

I'm fairly confident in my explanation, but if I've got this wrong feel free to jump in and set me straight. Basically, you use less muscle power by spinning faster (pulling more rope) in a lower gear (lighter pull) but you can still move the bike at the same speed (200lbs/20ft).

CdCf

Speed isn't the same. It's true that the speed of the bike is determined by the power output.
However, power is force times speed, and since our bodies transfer power via the pedals, it's the speed of the pedals that factors into the calculation, not the speed of the bike.

P = F x v

If P (power) is to remain unchanged, and we increase v (velocity), it's obvious that F (force) has to decrease. v is directly proportional to cadence in this case, since crank length doesn't change.

DannoXYZ 

Sorry, I should've clarified. Force is not the same as power. Force is an instaneous value, while power is that force applied over a certain distance in a certain amount of time. If you push a box of tools with 50lbs of force across the garage, you will have generated X amount of power. You can push that same box with the exact same amount of force, but push it across two garages and you would've generated twice the power 2x. Or you can push that box across one garage twice as fast with twice the force and generate twice as much power 2x as well. Force and power are related by this equation:

power = (F*d)/t ; force * distance per unit time

Speed on a bike is an indicator of power-output. So 20mph on a bike will require something like 250watts. There are multiple gears you can use to generate this power. If you look at the above equation for power, you'll see that there is an inverse relationship between d (distance your feet moves) versus t (time it takes to move your feet). To maintain same power-output, you can increase the distance your feet moves and/or reduce the amount of time it takes to do each revolution. Basically use lower gears. You can spin your legs 4 revolutions instead of 3 in the same amount of time. This gives you 4 sets of muscle-contractions instead of 3, meaning each contraction can be of lower force to generate the same overall power. Let's take the case of riding at 60rpms vs. 90rpms:

Power1 = Power2
Power1 = F1*d1/t1
Power2 = F2*d2/t2

Power = F1*d1/t1 = F2*d2/t2
RPM = rev/min = d/t
Power = F1*RPM1 = F2*RPM2 ; you end up with ratios of RPMs

F1*60rpms = F2*90rpms
F1 = F2*1.3

Basically what this tells us is that for the exact same speed and power-output, using high gear at 60rpms requires you to push on the pedals with 1.3 times more force on the pedals than lower gears at 90rpms.

8bitevolution

I know this turned into a physics discussion (which makes sense) after awhile and now most people have probably already decided this conversation was over but I just wanted to update everyone on my progress (two days later, that is).

I put a bike computer on so I have a better idea of overall speed and distance. It doesn't tell me much, just the basics. No heart rate monitor or anything like that.

The daily ride I'm doing is a mile and a half. I do it about 30 seconds shy of 10 minutes, most of the time going about 10 mph. I tend to get a bit tired towards the end, but already not as much as I did the day before.

This is actually a longer version of the ride that was making my legs burn. Now after riding, there's a little soreness but it's gone fairly quick. Not even 30 minutes later and really, I just like my legs need a good stretch. I've tried my best to incorporate the advice I got here and I think it's really paying off. I attempt to keep a really steady cadence and I think I'm doing pretty good. A lot of times, it just feels like my feet are going with the flow. I'm still getting used to being back on a bike so sometimes I get too distracted with other things to keep track of my cadence like I should.

After a ride, I'm not winded at all. Saturday and Sunday, I came home gasping for air like a fish out of water. Today, if I got on the phone right after getting off my bike, no one would be the wiser. Also, I found myself wanting to keep going and I would have if I didn't have to go to work.

So anyways, thanks for all the advice! It has been a tremendous help.

Walkafire

I would get a computer with Cadance. I rarely use the other stuff other then general knowledge, Cadance keeps me going! It will help you to Shift. (up/down)

As far as your saddle, it is a long and tedious process. So many things are involved.
I made several MARKS on the seat post and the saddle frame too. Things to keep in mind are:
Height
Forward/Back
Tilt (nose up/down)

It takes a while to dial it all in, but it is WELL WORTH IT, once you get it!

Good Luck!

8bitevolution

The bike computer was basically to get a feel for how fast I was going (I was very surprised) and what kind of distance I was riding. You don't get a good feel for the distance of a mile in a car.

I have no doubt about the value of a computer with Cadance but right now $$$ is a bit of an issue (having just bought my bike and all ) so for now, I'll have to make do with this which should be fine.

Sunday, I had vowed to get a new saddle no matter what. Yesterday I mentioned it to a guy at my LBS and he said it could take some getting used to. So I want to give it a try for a month or so before I buy a new one. And it's actually started to not bother me so much. I will look into adjusting tilt and such later this week if it's still giving me grief.

HiYoSilver

THANK YOU ALL for the physics explanations. I'll review them tonight, but it sounds like I should no longer kick myself for using lower gears and try to work on increasing cadence rather than using the higher gears. From what I gathered, while trying to multitask, if there are 2 gears with about the same GI [gear inches], you should pick the one with the lower chainring as you will get more speed for the power you generate.

Silverexpress

For the original poster.....

Go out and buy yourself a computer with a cadence function.This will help you quickly guage your pedal rpms.

So forget about how fast you can go on your bike for now, just focus on your cadence.

Next, get yerself a good heart rate monitor, and get to know the different ranges of heart rates and what they mean. Work them.

If you learn to focus on these two numbers, and learn to 'ride' them...I guarantee that it will make you a better rider quickly....everything else will be relative to these two measurements.....and that includes GEAR CHOICE and the foods that will fuel your engine.

"One day in the future, you'll be biking long, and all of sudden take notice of your legs smoothly pumping away. You'll suddenly be amazed at how relaxed your breathing is, barely putting up a sweat, as if your legs were a part of the bike and not yours. Painless.

Looking around you'll see that your with the lead pack in today's club ride...taking turns drafting with the three fastest riders. Today they take notice.

The best part is how you feel....NOTHING, but the coolness of the wind, and you'll be startled when you see your bike computer is showing 28 mph. The asphalt a blurr as it quickly moves underneath you.....truly mezmorizing

I've been there....it's an awesome state of being.....but it takes work. I did it on a $400 bike, the rest was blood, sweat, tears, and a love for riding.... ;-) Don't expect to much off the starting line. You'll get there eventually, just make sure your having fun all the way, and like a metaphor for LIFE, you'll soon realize it's too short of a ride" - JE

DannoXYZ 

You're welcome...


... almost... Gear-ratios with same gear-inches will result in exactly the same leverage and RPM and required force on the pedals. So a 38x13t gear is exactly the same as 52x18t, roughly 79 gear-inches. They both will result in the exact same cadence at the same speed due to the overall gear-ratio of 1:2.9.

To do what you want, getting more cadence at the same speed, use a 38x14t gear instead or a 52x20t. The big-ring gears are preferred since they rotate the links on the chain less and cause less friction in the drivetrain. What you're getting is more power for the same pedal-push force. This higher power will let you ride faster with the same muscle-force exertion as before.

sngltrackdufus

[QUOTE=DannoXYZ]I think everyone pretty much covered it. Just a minor physics clarification...


Power-output is actually the same regardless of gear. It's the torque that changes with gearing. So if you're cruising down the freeway 65mph in 5th gear @2500rpm, you'll need about 20hp. You can also use 4th gear @3500rpm to also generate 20hp, but you'll notice that the throttle-opening is smaller. The 4th gear spins faster, you get more combustion pulses per second, so each pulse can be smaller to generate the same power-output.

The way that works on a bike is you can be cruising at 20mph in a gear that requires 75rpm. This requires a certain amount of force on teh pedals. You can also select a lower gear, so that 20mph requires 90rpms. The muscle-force needed on the pedals will only be 80% as much as before.


Burning legs are caused by lactic acid. This is due to anaerobic fermentation in your muscles due to high-effort. It's inefficient and requries a lot more oxygen to clear out and causes muscle soreness as well. The LT-lactate threshold is the exertion level where your muscles transitions between efficient aerobic operation into inefficient anaerobic mode. Stay below this exertion level by using lower gears and spinning your legs faster. Same power-output and speed, but you can push on the pedals lighter. This extends the distance you can ride before you have to stop due to muscle-fatigue.[/QUOTE

3 Scoops of Cytomax in a water bottle will fix that........