Shifting While Sprinting
 

I dont want to make myself sound like a fool (moreoso that I am..)
but what do you guys think of shifting while going for an all out sprint?
My reasoning being that, if I shift while doing a full burst, will the shift still go smoothly or will there be a chance of something going largely wrong?
Just as an input, I was going 35 sprinting and wasnt sure if I should go up to the higher gear or stay where I was- I stayed where I was.

Yea, you'll end up like umbrellaman in phoenix's photos.

Ease up when you shift. This should be obvious. What are you, some sort of n00b?

I've shifted in sprints in races, I wouldn't recommend it though...

If your drivetrain doesn't suck, shifting when sprinting is fine.

If you're using SRAM, sure!

Just kidding, however my Rival does shift fine under load.

I don't race, therefore I don't really need to sprint. However, I think the best thing to do is to make sure you're in the right gear from the beginning. If you do have to shift you can probably shift under load if you have a decent group set. If you're not sure you can do it without messing up, in your head, compare how much time you'd lose if you didn't shift and just pedaled faster to if you were to shift, but if it's not going to be smooth.

If you are over-geared, it's probably best to shift down to get in the right cadence. You can't sprint in too high of a gear, but you can definitely spin up to speed in a lower gear.

I've lead up to a sprint thinking my rear derailler was out of allignment. I went into the sprint and pounded the gears, as is normal four our group at that point, then pulled off to the regroup lot. My chain sounded like hell at that point and I finally looked down to realize that things didn't look right. Fortunately, one of the local shop owners was on my wheel and saw that my chain was about to self destruct. He had to pull three links, held in by pins which he barely had to touch to get to fall out.

In the end, I paid for his beer at the end of the night (didn't charge for labor), bought a new chain from him, and a new chain tool to carry with me since mine turned out to be a piece.

I learned that night, the importance of proper shifting, and of letting off the gears when I do so. I'll readily say I'm still learning since I've only recently crossed my first 1K mile mark since about March. But in that amount of time, I managed to shred a brand new chain. Don't do that.

If that chain had let go in the sprint, I would have been eaing the pavement at 35mph, and been having a really ****ty night. Mind your chain if you're going to mash the gears, and pay attention to wear when it shows up.

That picture looks like me in a 'cross race last year, but without the mud.

Oh, and I didn't have an umbrella.

Glad that chain guard is keeping his pants clean.

That is the best/worst pic I've seen this year. It pains me to look at it twice...

I virtually always shift in sprints, otherwise I'm not accelerating that much. I usually shift as I jump, then one more shift during the sprint. If it's a slow sprint (like uphill) I may shift more times.

I try to shift at the top/bottom of the pedal stroke (it's kind of instinctive now), full power, but at those points in the stroke "full power" is not that high. However I regularly end up shifting in the heart of the downstroke. It's all good, with the ramped cogs and modern chains (hardened pins). I used to shift under 100% with toe clips + straps, a soft Sedis chain, and unramped cogs. I'd pull my shoe out of my pedal even with 2 toe straps cranked so hard that my feet hurt. With 3 straps I only pulled out once, but that was about when someone invented clipless pedals.

A chain that fails is a chain that shouldn't be on the bike in the first place, either due to wear or improper installation. I've seen many new chains fail at the spring series at Bethel, new ones installed improperly.

cdr

The more watts your putting out in the sprint, the harsher the shifting and the greater chance of something breaking. Since I can only muster 95watts on a downhill sprint, I can shift at any time!;)

it's fine.

that being said, unlike cdr, i infrequently shift when sprinting, my sprinting style is short, so i prefer to do my shifting prior to my jump.

I rarely don't shift in a sprint

I shift in sprints all the time. Just click the shift up button at 4 o clock in the pedal rotation, then it will shift at 6 o clock, where you really aren't putting a lot of power on the pedal, so it will shift just fine.

EDIT: I see cdr has already said this. Call it an elaboration.

I would focus less on figuring out how to shift in a sprint, and focus more on choosing the right gear for the terrain and the pack speed, high cadence riding out of the saddle, and your jump.

+1

I always shift in a sprint. Drivetrain has yet to fail me.

plus one

Good to be in the right gear for a 200m sorint, but There's really not a lot to figure out regarding shifting. Bang the gear and go. Bang the gear and go. If you can't do that get a new mechanic...it's 2010.

Itll be ok.

+ 7 (I think that's what we're up to) on you can, and often should, shift in a sprint.

This is the reason that STI was a significant deal to racers.

It's also the reason that SRAM shifters are designed so that you can pull the shifter in close to the bars, independent of the brake lever.
(allowing easy shifts in the drops in a sprint)

I used to use a right/rear bar-end shifter to my advantage, before there were any brake/shift levers. I could jump in, say, a 14, stay with even the best jumpers if they were in a 12 or 13, then shift up and jump again, and again, and use my slightly fresher legs to gain speed. I had a chance at beating this one guy who was waaaay better than me in the jump but equal in top speed.

When he got STI I couldn't beat him anymore. I'd always be going the same speed as he was, just 10 feet back.

Standing at high rpm is not that efficient (high to me is over 130-140 rpm). If you can sit at high rpm that's better. Standing is usually better at lower rpms, say under 120.

I shift when I sprint, usually I have to find the "sweet spot" and shifts very smoothly, it's not loud or anything. And I have a 105 RD and Tiagra shifters.