Sprinting question - Power/weight question

okgo

I've noticed that recently when going for it in the drops the back wheel seems to be all over the place, skipping about, coming off the ground etc. Is this down to poor pedaling technique? Too much weight over the front wheel? Its not such a problem on a smooth road in a training ride, but I would rather it felt a bit more stable in a race where that wouldn't be so ideal! Any thoughts?

Second question is more one for the coaches/ power people I think...

I've been trying to lose weight, and its slowly coming down currently around 79 kg down from 95+ 18 months ago, so its been a big change, but not enough really it would seem. From looking at various power profiles and duration it would seem that my strengths are probably in short burst stuff (15s-5 min), my longer power is OK but I don't think its anything to write home about. So the question is really, will losing a lots of weight negate that power, or is it a case of if you've got it,you've got it? In an ideal world I want to get nearer to 75kg which I think would see quite a benefit assuming I can keep the power levels, but as said, the only worry is that in doing so (which is no mean feat it would seem) I start to lose what I'm clearly best at...


Any thoughts on that would be appreciated, there's been mixed opinion in my club on it, but I'm just interested to see what others have done, or have seen in their own power/weight loss etc.

amaferanga

Weight too far forward.

As for the losing weight bit - if you lose fat then how would that impact on your power?

okgo

amaferanga wrote:

Weight too far forward.

As for the losing weight bit - if you lose fat then how would that impact on your power?

Ok, how does one sort that? Does it mean the drop is too aggressive on the bike? Or?

Don't get my wrong, I've lost a lot of fat, there's not a lot left now, and the reason I weigh is because I had bulk muscle from weights etc, so that is the worry, to get down to 75, it would involve more muscle loss than fat, and I've already lost significant muscle mass to get this far (but didn't have a powermeter before so can't tell if it has made much difference...)

jibberjim

okgo wrote:

Ok, how does one sort that? Does it mean the drop is too aggressive on the bike? Or?

No it just means you lean too far forward - do you really see it on a flat sprint as opposed to a slight uphill one like Ham Dip or "Jim's Corner" where the forward position is more normal and you need a slight concious thought not to?

okgo wrote:

Don't get my wrong, I've lost a lot of fat, there's not a lot left now, and the reason I weigh is because I had bulk muscle from weights etc, so that is the worry, to get down to 75, it would involve more muscle loss than fat, and I've already lost significant muscle mass to get this far (but didn't have a powermeter before so can't tell if it has made much difference...)

Muscle size is going to make very little difference to power at any duration, only very, very short durations in high torque situations (so low cadence like accellerating from a dead stop, or super grinding up a hill) but those are not what you see in a road race sprint. I've had power from when I weighed 83kg+ all the way down to 71kg, my 20second power has been identical at all of them and my peak 1-5seconds was at 73kg despite doing more racing where I'm likely to see it at the heavier weights, my BMI is close to "underweight" at 71kg, although I still have fat in the areas I carry it.

okgo

Haven't done a flat sprint on that bike really, well I have, but for some reason I stayed in the hoods...Does lead me to think that perhaps I'm not suited to the drop if its not automatically where I do for a sprint..

But yes, last night in that corner, the back wheel was all over the shop, it seems to be a bit more obvious since I changed shoes to those silly stiff Bont ones...


Interesting re weight, so really there shouldn't be any issue in dropping right down (well as far as I can manage, I'm already being told I look thin, obviously not the company of the cycling club!)..

jibberjim

okgo wrote:

Interesting re weight, so really there shouldn't be any issue in dropping right down (well as far as I can manage, I'm already being told I look thin, obviously not the company of the cycling club!)..

Really does show how societies views on weight are screwed up at the minute porky

okgo

In clothes people look quite different to lycra though

P_Tucker

okgo wrote:

In clothes people look quite different to lycra though

naked people look quite different to lycra too

Im Bald Ok

Try upping your cadence, pork chop.

okgo

Was at 120-130 rpm...

Im Bald Ok

Then I would guess it's your technique? Some people can be right over their front wheel in a sprint and their back wheel will never come off the ground. Look at pictures of Cav in a sprint.

When you're in the power phase of your sprint pushing down on the pedals it can be easy to give it the beans all the way down to the 6 O clock area then completely ease off the power. Sometimes this will cause your back wheel to pop off the ground as when your leg comes back up, it can take the rear of the bike with you slightly.

Not sure if that makes for good reading or is even understandable. Next time you're out try and sprint and consciously think about pedalling circles rather than just getting the power down.

oldwelshman

Im Bald Ok wrote:

Then I would guess it's your technique? Some people can be right over their front wheel in a sprint and their back wheel will never come off the ground. Look at pictures of Cav in a sprint.

When you're in the power phase of your sprint pushing down on the pedals it can be easy to give it the beans all the way down to the 6 O clock area then completely ease off the power. Sometimes this will cause your back wheel to pop off the ground as when your leg comes back up, it can take the rear of the bike with you slightly.

Not sure if that makes for good reading or is even understandable. Next time you're out try and sprint and consciously think about pedalling circles rather than just getting the power down.

In sprinting It is normally the upstroke on the leg pulling up that spins the back wheel.
If you look at Cav sprinting his head is forward over the bars and he is low, but his hips are mostly centred over the cranks which helps keep the back wheel down.
I sometimes hop the back wheel on the track when kicking hard bit for full sprint am sat down so dont get that spin then.

racingcondor

okgo wrote:

Haven't done a flat sprint on that bike really, well I have, but for some reason I stayed in the hoods...Does lead me to think that perhaps I'm not suited to the drop if its not automatically where I do for a sprint..

But yes, last night in that corner, the back wheel was all over the shop, it seems to be a bit more obvious since I changed shoes to those silly stiff Bont ones...

I'm wondering if there isn't a bit of a problem with bike fit.

If your bike is to long (either a large frame or long stem / reach on the bars) then I wouldn't be surprised if reaching for the drops is too far, it could also mean that your saddle is too far forward making it hard to keep your weight back.

Could also be a mixture of rider flexibility and a short head tube bike though.

Would help to know how tall you are and what you are riding (bike, size, stem length and what bars and brifters you are running).