keyven

I've never had a problem with riding out of the saddle during my younger years but quite recently when I started cycling regularly again (with two different bikes), it just feels like the cranks may be too long. I'm about 5'7 with a 29 inseam.

It constantly feels like I'm "falling forward slightly" every time the crank completes one turn. Effort is primarily on getting the pedal to the apex of the revolution before gravity takes over and I 'fall forward' . Rinse and repeat.

Anyone else had this problem?

CliffordK

How long are your cranks?
What type of bike?
170mm, 172.5mm, and 175mm cranks are most common, and usually marked on the back of the cranks, but you can go to 165mm or 180mm, or other lengths too.

Do you use toeclips or cleats? What about pulling up on the opposite leg?

Much of your pedalling while standing is, in fact, letting gravity do its thing. I guess I'm having troubles imagining your feeling of falling forward. Could it be too long of a handlebar stem, and perhaps too vertical of a stance when standing? Loss of flexibility in the back/hips?

keyven

One is a Giant MTB and the other is a Brompton - I believe both should be 170mm cranks with standard platform pedals.

My thinking is that "falling forward" while pedaling out-of-the-saddle is not giving me much power transfer. The feeling is like pedaling at a preferred cadence but the gear is just one step too high.

CliffordK

So, when you say "falling", does that mean that you're not getting enough downward force on the pedals, or that you're feeling unstable like you're falling off the bike?

Longer cranks should give you more leverage, and shorter cranks less leverage. However, people tend to be able to crank the shorter cranks faster than the longer ones.

As far as the dynamics of "standing on the pedals".

With flats, you apply essentially 100% of your weight on the drive side, and then reduce the pressure on the non drive side. But you're letting the weight of your body do the work (as well as straightening the leg under gravity).

You can't really push down any harder, however, you can lift up on the handlebars somewhat, increasing the downward force on the pedals. By pushing the frame of the bike away from the drive side, you're also effectively raising the bike to meet the downward motion of the pedal.

If you have clips or cleats, you can also pull up on the opposite leg. There is some debate on how much one is able to effectively pull up, but it 100% unloads the opposite pedal, and puts some upward force on the crank, and consequently also increases the effective weight of the person and downward force on the drive side.

catonec 

so I may be way off base here but it almost sounds as if when you stand up to pedal the cranks have "less power" in them which would make the downstroke seem weak and thus the falling forward feeling.

when you stand up you need to upshift so its harder to turn the cranks.

When I hit a big hill I start it in what ever gear I happen to be cruising the flats in and stay seated. I pedal until its tough to turn then down shift one, pedal till tough, down shift one, repeat until I run out of gears. Then I stand up and immediately up shift 5 or 6 gears, where ever it feels good. I power stroke for a few, rocking the bike back and forth a little to help out, and then when I get tired I sit back down. Now I have 5 or 6 gears to walk back down through.

Not sure if this is your issue but I hope It helped anyways. gluck.

ursle

Longer cranks for hill riders, shorter cranks for track riders, falling backward would be the axle to far out on the foot, falling backward would be the axle to far back on the foot

fietsbob

Usually it does not matter .. MTBs often bump the arm length spec up from 170 in the larger Sizes of bikes ..


Bromptons have a Low BB so 170 is the way they ship .. Bottom of pedal stroke puts it close to the ground.

Thus saddle to ground distance is Lower for stoplight 'dabs' , Putting your foot down..

LGHT

I used to feel this way also, but an advanced ride my problem during a ride and suggested I shift up 2 gears and lean forward so my shoulders are in line with the brakes and try and push down and back on the pedals. This really helped a lot. Not only did it feel a lot more comfortable it allowed me to produce more power at the same time. Takes some time getting used to the position, but once you get it you will love it.

ESTrainSmart

Hi, I'm a Bike Fitter, Coach, Personal Trainer (ACE certified), Sports Conditioning Specialist (ACE certified) and I hold a Degree in Kinesiology. Crank length is the number one variable to optimize and yes, it will affect your standing technique and power output. Unfortunately, crank arm length calculators are as good as guessing because there is no correlation with crank arm length and inseam or leg lengths (femur to tibia ratios, etc.).

I am working with researchers to study the validity of my crank arm length mobility and subjective test, but the symptom you described fits in the category of a crank that's too long. If you try to increase the cadence, the hips will feel unstable and cause excessive lateral movement, but if the gear is too hard, it will feel like the power phase of the pedal stroke is excessively long, but the hips/ pelvis will feel more stable, especially the more upright you stand. As a result, an excessively long crank will cause you to frequently shift to an easier gear, but always favor the harder gear and slower cadence for a smoother pedaling technique.

keyven

Thanks - it's good to get some reassurance before I start focusing on shorter cranks. I'm no competitive cyclist but I'm sure I'll enjoy cycling that much more once this aspect is fixed.

I was told by a friend that I was "imagining" the whole thing even though my body told me otherwise.

keyven

Thanks everyone for your helpful comments. I will definitely give some of these suggestions a try.

Carbonfiberboy 

IMO you're just out of shape, out of practice. At 5'6", I seem to be able to ride whatever crank length, 165-175. I tend to pedal a slightly slower cadence with the longer cranks, maybe 2 beats.

Pedaling smoothly out of the saddle is a real trick. When you are seated, it's easy to push forward at the top and pull back at the bottom, using the saddle for leverage, which makes it easy to have a smooth, comfortable stroke. However when standing, that's more difficult. Most people find cadences of 60-70 the easiest to pedal while standing. Try getting on a nice flat road, coming up and pedaling. Shift while out of the saddle by sort of stuttering the pedal stroke at TDC and shifting during the micro-pause. So vary the gear and find what seems easier for you. Probably your biggest gear or next to largest will be easiest on the flat.

In any case, what works is lots of practice. Every time you start up a hill, start it standing and hold the stand until your legs start to hurt, shifting as you go. The more you do it, the easier it will get. It's just a neuromuscular coordination issue. When I go from sitting to standing for a rest, I'll shift up a ring and maybe also a cog or two in back.

jyl

Use a higher gear.

Normally when you pedal standing, you "stand on" the pedal and let gravity (your body weight) plus your straightening leg push the pedal down. The pedal should resist enough that you can support yourself on the pedals alone, and barely have to hold the handlebar. If you are in too low a gear, then the pedal doesn't resist enough and your weight pushes the pedal down too quickly. "Too quickly" means a cadence higher than you are comfortable with. Most people pedal standing at a lower cadence than they use when seated; around 60-80 rpm is common. If there is not enough resistance at the pedal, and you are standing, you will find yourself partly supporting your body weight on the bars.

To feel an extreme version of this, shift to your lowest gear and pedal standing on a flat road, going at least 10-15 mph. Your cadence will be uncomfortably high and you'll end up trying to hold yourself up by the bars. Then shift to your highest gear, slow to 5 mph, and start pedaling standing. Your cadence will be very low, you will feel like you are climbing stairs, and you will only need to lightly hold your bars for balance and control.

So try a higher gear, the result will be more resistance at the pedal, no "falling forward" sensation, and a lower cadence.

Your legs will also get tired quickly, until you build the muscles used by standing pedaling.

Garrison572

i a new one,and i am confused about the size of a bike,what's the meaning of 27.5er 650b carbon frame?i am 175cm tall,which size of frame should i buy?[h=1][/h]

ESTrainSmart

That's the tricky thing about crank arm length. Almost everyone thinks it's a psychological or technique issue. While a crank can vary by 2.5mm in length, range of motion at the hip, knee and ankle changes drastically and no amount of training can change the physics of that relationship.

Before I studied the Biomechanics thoroughly, I thought I could adapt my body to an excessively longer crank through training. I spent a full year doing neuromuscular drills/ exercises, mobility and flexibility work to improve my technique, but never saw any meaningful results. It was really eye-opening to spend a year trying to fix the problem through training, then instantaneously have perfect technique again upon changing the crank to my optimal length. You'll absolutely enjoy cycling more because you'll be able to ride with significantly less effort.

I do want to mention, however that it's possible to go too low. In this situation, it will feel like the power phase of your pedal stroke is always cut too short. As a result, you'll push yourself upwards at the bottom of the pedal stroke which will create a bouncing effect when you pedal out of the saddle. Just FYI just in case you end up getting something excessively short.

catonec 

Edit Post
at 175 you're 5 ft 7 inches. I would think you are going to want a 52 or 54 cm frame. This of course is not an absolute answer. You may want to go slightly larger or smaller depending on your body shape, the geometry of the bike, the length of the stem... But that is where I would start.

When someone is talking about 26, 27.5, 29, 650, 700c they are referencing the diameter of the wheel. Most mountain bikes for a long long time had 26 inch wheels, 650B's were reserved for smaller frames. 29 inch wheels came around not to long ago for mountian bikes. 700c is most common on modern road bikes, 27 was the standard 30 years ago.

the next big consideration when buying a bike is what material the frame is made of. there are many variations but the 3 basic are steel, aluminum, and carbon fiber (a type of "plastic'"). each have their pro's and con's but that is a debate Im not going to start willingly.

good luck.

Garrison572

Thanks very much!i would search the internet for more information,then maybe nest time i can be a pro.lol....

CliffordK

I just finished assembling a "new" bike today.
Somewhat shorter, but longer frame.
High seat.
Low bars.

Perhaps a bit more "racy". However, it certainly felt a bit awkward the first time I got on it, especially while standing and pedalling. I've got a little more evaluation to do, then perhaps I'll raise the bars and shorten the stem.

Anyway, one's posture on the bike may affect the feeling of stability and "falling".

fietsbob

Not to me .. 170,172.5, 175, 180* . use the different bikes with them without thinking about it .

* it did contribute to making the illusion of a too steep seat post being a lesser angle..

a too steep a seat tube, for my tastes, + zero set back Post, I've Since bought a seat post with setback Too..

Longer crank , the saddle is just that little bit lower. as the saddle to pedal distance is kept the same. [same Legs]

Olympic team bound ? racers worry about this ..



Folding bike, Brompton, has a low BB, so has only a 170 crank .

ESTrainSmart

Read this: An Error Occurred Setting Your User Cookie
And this: An Error Occurred Setting Your User Cookie

I've already done the research on this, but for those who strictly ride at very low power or lack body awareness, they can't perceive how their body negatively responds to crank arm length. The first link shows that there are clear differences in aerobic performance between crank lengths. I also have a research article showing significant differences between 2.5mm increments. The differences are there despite that you are unable to percieve them. However, as long as a non-competitive cyclist shows no evidence of biomechanical deficiencies that can lead to overuse injury, I don't recommend changing crank length due to costs. As demonstrated in the second link, simply adjusting saddle height doesn't compensate for the minimum hip, knee and ankle range of motion at the top of the pedal stroke. The minimum angles is exactly the reason why the OP experienced issues standing and putting out power in the saddle. It causes the pelvis to shift and tilt which forces a drastic change in center of gravity at the initial power phase of the pedal stroke, hence the falling sensation.

fietsbob

I like Oatmeal Rasin Cookies Best.

dave42

Me, too. And oatmeal creme pies.

chaadster

Your perspective is interesting, and I've never thought about crank length in that way before. I'm not sure I find it compelling quite yet, primarily because I just don't hear complaints like the falling sensation thing much at all, and honestly, I don't think I ever have in the past 30 years of cycling. I do know, however, that you probably have more opportunities to field those kinds of complaints given your work, so I'm curious to hear more.

Are you basically saying that excessively long cranks open the hip angle too much at the bottom of the stroke, pushing/tipping the base of the pelvis forward?

If so, do you think the "best practice" of sprinting from the drops mitigates that effect? What about saddle to bar drop?

ESTrainSmart

I wasn't too interested in crank length until I corrected it and experienced an immediate 20-30 bpm drop in heart rate for the same speed. My pedaling technique instantly restored back to normal as well. In terms of power, there are reports of 100 watt improvements just from correcting crank length. The improvements I experienced were nothing short of massive.

The reason why I was in this situation in the first place was because I was forced to ride a completely new bike for 2014 when the tire casing of my new Conti GP4000S failed instantly after a sprint which totaled my previous bike. The new bike had a longer crank arm. I spent the full 2014 racing season unaware that my cranks were too long, but aware of major differences in my pedaling technique, cadence and heart rate.

I immediately blamed myself for the drop in performance because I didn't want to be "that person" who blamed the bike. I implemented various neuromuscular, mobility, flexibility, power lifting and strength conditioning protocols to combat the symptoms I experienced, but never saw any meaningful improvements. Changing the crank arm length instantly solved every problem I had tried to fix all year.

Sorry about that long background. I'm super passionate about this topic because of how much it affected my performance. I'm presenting my crank arm length test to a few research boards to have it studied for its accuracy.

Anyway back to your questions! When the cranks are too long, it causes the hip, knee and ankle to reach its optimal range of motion for power production too early. As a result, the rider will never feel like he or she is using their full potential throughout the power phase, especially with explosive efforts. Using a piston in an engine as an example- it's similar to the spark plug firing before the piston reaches the top. The stretch coming from either the pelvic wall, core, hip, knee or ankle musculature adds extra resistance to each pedal stroke through a co-contraction. It's like holding an active stretch repeatedly.

In terms of sprinting with long cranks, being on the drops will make things worse. A rider with long cranks will naturally favor a higher position with the hands on the hoods. If the rider forces the hands on the drops, the hips will shift forward towards the handlebars which will drastically reduce gluteus maximus activation. The reduced glute activation leads to a significant drop in power.

dave42

What alterations did you make to your bike fit(saddle height, setback, etc.), when switching between longer and shorter cranks?