kwakster928

I have a really dumb questions for everyone out there.

I have been noticing on my bike when I am smashing the pedals while sprinting, I occasionally lose the grip on the rear wheel. It feels like the real wheel lifts up for a fraction of a second then touches the ground.

I am almost certain that it is my pedaling technique not my bike. (Maybe leaning too far forward) Have you guys experience anything like this? If it is my technique, what can I do to fix this problem. To be honest it is quite scary to lose grip on your rear wheel.

hyperlitenerd

I have this happen to me some times too. It happens when I stand up too much and get to far forward, if I put my butt back the wheel gets back on the ground.

SalsaPodio

It's your pedaling technique. There are a lot of threads on it, particularly in the racing forum.

See here: https://www.bikeforums.net/showthread...heel-in-sprint

Val23708

your butt cheeks should be close to brushing the nose of your saddle while you're sprinting. Also make sure you arn't trying to keep the bike straight up (some people try this and their rear wheel skips side-to-side - thus making a slower sprint)

kwakster928

Thank everyone for a quick response.

garethzbarker

his totally makes me think of someone on a cartoon burning rubber on a bike.

Kind of Blued

Thanks for the link above. This happens to me when I'm sprinting up to speed while turning in an intersection. It's more scary while you're turning near traffic and your rear wheel skips SIDEWAYS as well as up/down.

WHOOOSSHHH...

To much torque. It's like stomping on the gas pedal and squealing your tires. To much gas. Add weight over the tire, or ease off the gas ...

walshconor

depending on the road surface over-inflating your tires could also cause skipping.

rolliepollie

Might be an obvious question, but what's your psi at? Lowering by a few lbs would improve grip a little.

gregf83 

No it's not due to too much torque. Top sprinters putting out 2000W don't have this problem and they exert more torque than anyone on this board.

Dan The Man

I am betting that they have smoother torque curves when sprinting. Consider that if you hammer 2000 watts into just the drive of your pedal stroke while standing and leaning forward you will have spikes in your torque where you are pushing hardest. Think of it like the difference between turning your pedals smoothly and hammering them like pistons.

thisisbenji

This used to happen to me all the time. I went to the track and worked on my form and was able to fix it in one day. I found that I just had to let me bike move side to side more and it fixed it.

gregf83 

They don't have smooth torque curves. The problem isn't with peak torque which occurs at approx 90 degrees of crank angle (i.e. crank arms horizontal). At this point the rider is pushing down hard while pulling up hard on the handle bars. The problem is more likely occuring at the bottom of the stroke. The rider continues to extend his leg but the pedal is bottomed out so the rider's body (and center of gravity) rises up. This is what causes the unweighting of the rear wheel.

The problem can be addressed by doing high cadence drills. The idea being to get the cadence as high as possible without bouncing in the saddle. Do a few drills up to 180 RPM and that should fix the wheel skip at normal sprinting cadence.

Blackdays

/facepalm

Spam16v

happens all the time.

spock

I think it happens when you are pulling up on the pedal stroke while the other leg is transitioning to push down and your body is in gravitational transition because of all the movement. You could perhaps use a smoother stroke or a heavier bike.