Gear selection for sprint finish

slogfester
slogfester Posts: 39
edited December 2009 in Road beginners
If I have trouble keeping the front wheel down when sprinting, am I selecting too high or low a gear when I hit the gas hard at the end?
At the w/e I was with a small group doing c. 30 mph during the lead out @ c. 100-110 rpm (data from a Polar comp). When the jump came I went up a few gears (it all happens so quick I never know) and sprinted out the saddle in the drops. Initially the front wheel kept lifting which didn't help with control (it was wet) and it feels like your wasting a lot of power. I suspect I sub-conciously backed off just a little to maintain control over the bike. Max speed was 37 mph (cadence monitor failed to record final rpm, but previous data suggests @ c. 120 rpm).
Thanks

Comments

  • softlad
    softlad Posts: 3,513
    I don't really think science comes into it. If you're going fast enough, you're in the right gear - if you're dropping back, then you're not.

    Not really sure why your front is lifting if you are in a proper forward sprint position.....
  • oldwelshman
    oldwelshman Posts: 4,733
    edited December 2009
    Unless your sprinting uphill (doubt it if you hit 37mph) you should not lift the front Wheel up. Seems your body position may not be quite right.
    Have a look at Cav in the final stage of TDF this year for good sprinting position.
    I never select a particluar gear, I just go by feel as I dont use the same gear every time and tend to sprint on a lower gear than some.
  • @oldwelshman - what do you mean by your front heel thing? Just curious!

    Two things I'd say. First, you'd probably need to get your body more forward and down. Second, how are your bars set up? It really helps keeping the front planted if you can get a really strong pull/push, which tends to mean hands further towards the end of the bars (where they are more horizontal), rather than fully in the curved section bends.
  • Pross
    Pross Posts: 42,165
    @oldwelshman - what do you mean by your front heel thing? Just curious!

    I think he means wheel but missed the w! :lol:
  • Many thanks for useful replies. It hasgiven me some clues and made me think...

    Hand position might be it. Sprinting in the drops has never never felt quite right on my current bike (Merida Scultura Team FLX) which was purchased primarily for a dodgy back and long alpine ascents. It feels a bit cramped when sprinting. The tops of the bars dig in to my lower forearms when in the drops. But the bike is brilliant for 99% of the riding I do, so it stays. I'm sure as suggested, by changing a few things and technique I can alleviate these problems.
    The bars (Ritcheys I think) are set just a few degrees down from horizontal (pointing down?). If I move my hands towards the end of the bars in order to clear my lower forearms from the tops, I start to run out of bar! Perhaps I need to get longer ones or a different shape? There is only 2 inches of 'flat' at the end- much less than a fist, so I have to have my hand half on the flat and half on the angled bit. (sorry, hope you can follow me here). So perhaps that is why in a manic sprint I might be instinctively grabbing the longer (c. 3.5") angled bit and hence my lower forearms pressing (painfully) against the tops. I guess with my hands not pressing down fully horizontally, my weight is not fully over the front end?
  • softlad
    softlad Posts: 3,513
    if you want to get your weight further forward, try sprinting on the hoods..
  • slogfester wrote:
    Many thanks for useful replies. It hasgiven me some clues and made me think...

    Hand position might be it. Sprinting in the drops has never never felt quite right on my current bike (Merida Scultura Team FLX) which was purchased primarily for a dodgy back and long alpine ascents. It feels a bit cramped when sprinting. The tops of the bars dig in to my lower forearms when in the drops. But the bike is brilliant for 99% of the riding I do, so it stays. I'm sure as suggested, by changing a few things and technique I can alleviate these problems.
    The bars (Ritcheys I think) are set just a few degrees down from horizontal (pointing down?). If I move my hands towards the end of the bars in order to clear my lower forearms from the tops, I start to run out of bar! Perhaps I need to get longer ones or a different shape? There is only 2 inches of 'flat' at the end- much less than a fist, so I have to have my hand half on the flat and half on the angled bit. (sorry, hope you can follow me here). So perhaps that is why in a manic sprint I might be instinctively grabbing the longer (c. 3.5") angled bit and hence my lower forearms pressing (painfully) against the tops. I guess with my hands not pressing down fully horizontally, my weight is not fully over the front end?

    Sounds like you've got anatomic bars? These can be a real issue for sprinters, but can also work well (both Cav and Boonen use anatonic bars - have a google for pics of their bar an dhand positions, Boonen has his bars really angled up and htey have a good long section at the end. Cav has his hands far more vertical), assuming the bar suits. Sounds like it doesn't. The key thing is: length of the end section; angle of the "anatomic" section. I had Deda anatomics for a while - great bars for comfort, bad for sprinting, becuase the kink in the bar was (just like you) exactly in the wrong place and the horizontal section way too short.

    Back to your issue. If your forearm is impinging on the top of the bar, then this will definitely affect your sprint, because you won't be able to really muscle the bars, which is key to getting power down and keeping the front well behaved. New bars, methinks! Compact bars might well suit you well - you can basically grab them wherever you like for a sprint and they're ok, very comfortable in the drops due to the shape and shallow drop. Definitely worth trying - you can pick up FSA omegas for cheap.
  • PS Compact bars aren't the last word mind, they just provide a very good compromise between comfort and sprint performance, better than anatomics IMO. I still think traditional curve bars are king when it comes to sprinting!
  • huuregeil, many thanks for sound insight... yes, looks like i have anatomical bars.
    I thought my old bike must have had traditional bars because it felt great for sprinting, but looking at pics it too had anatomic. Perhaps it felt better (for sprinting) because it had a longer reach (standard geometry and longer top tube)? (And hence, along with being alu, unfortunately did my back in, so it had to go!).

    Could only find one decent side-on/action pic of Cavendish hand position:

    http://www.cyclingweekly.co.uk/imageBan ... 202009.jpg

    But I aint no Cavendish (he's younger ;) ), so I'm not tied to anatomic. Heck, until this thread I didn't even know I had them! But identifying alternatives on internet and/or LBS could be tricky. I guess you never know what they really feel like until you hit the hammer?

    Further pointers for shopping? Just the length of the flat piece and angle of anatomical part? Does bar thickness play a role, i.e. shorter flat piece mitigated by fatter bars? Ditto bar width? I'm also a swimmer, so have bigger shoulders than your average dedicated cyclists.

    thanks again
  • I'd keep things simple. With a bad back, you almost certainly want shallow drops. This means two bar shapes are worth trying:

    1. Compact - e.g. FSA omega, 3T ergosum/ergonova
    2. Classic shallow (aka Italian bend) - Deda 215/Newton, Ritchey Classic, 3T Rotundo,

    Pay attention to the reach of your current bars, and the height of the hoods relative to the tops. Compact bars place the hoods roughly level with the top, shallow drops come a bit down the bend. Pick bars to keep the hood position in the same place, so you don't balls up your usual riding position. If you're big shouldered, buy bar widths to suit (e.g. likely the widest ones!). There's not much difference in the shape between the various compact or shallow bars, they'll just have different reach/drop dimensions. In the case of shallow bars, you might want spacers to bring the bars up, to compensate for the relatively lower hood position.
  • bigmat
    bigmat Posts: 5,134
    I had similar problems the last time I attempted a sprint. I was testing out my new 11 tooth sprocket (had been running 12 before) and hit 37.9mph but started to back off as my front wheel was jumping about a bit. Not so much lifting up, more side to side I think, probably as a result of jerky pedalling style putting the power down. I would say that a lower gear and higher cadence would probably lessen the issue, but also would slow you down a bit as well (your legs can only go so fast!) - the real answer probably lies in having a good grip on the bars as suggested above and maybe working on keeping the bike position as upright as possible as you get the power down.
  • thanks for great advice.

    I'm struggling to find and measure the exact specs of my current (alloy) bars. I can read 'Ritchey WCS Triple butted TRX50', but the model name is covered in bar tape, which was so well put on by a mate I'm loathe to take it off at the moment.

    Perhaps they are the 2006-7 equivalent of these?

    http://www.wiggle.co.uk/p/cycle/7/Ritch ... 360043146/

    But here's the weird part. They are definately 40 cm (centre to centre) width, which is the smallest size (I'm not the Hulk, but I'm wider shouldered than your average dedicated cyclists) but as far as I tell, the drop/reach is the longest 144/82 mm, possibly even more on my 2006-7 model?
  • oldwelshman
    oldwelshman Posts: 4,733
    MatHammond wrote:
    I had similar problems the last time I attempted a sprint. I was testing out my new 11 tooth sprocket (had been running 12 before) and hit 37.9mph but started to back off as my front wheel was jumping about a bit. Not so much lifting up, more side to side I think, probably as a result of jerky pedalling style putting the power down. I would say that a lower gear and higher cadence would probably lessen the issue, but also would slow you down a bit as well (your legs can only go so fast!) - the real answer probably lies in having a good grip on the bars as suggested above and maybe working on keeping the bike position as upright as possible as you get the power down.

    Sprinting on an 11 tooth? :D
    However did they manage years ago with only a 13 ?
    Maybe you should try higher cadence and lower gear sprinting to see if it stops the "wobble" .
    If I tried to turn a 11 in a sprint I would get left behind as I would never get it up to speed.
    I usually use 13 or 14 but even lower depending how it feels.
  • bigmat
    bigmat Posts: 5,134
    When I say "sprint", I mean riding balls out as fast as I can - no way I'd have the explosive power in the 11 to keep up with the action, but wanted to see how fast I could move on the flat with my gearing (I've got a compact up front). I think my conclusion, in a round about way, is that to avoid wobble a lower gear is probably better so I think we're in agreement!
  • oldwelshman
    oldwelshman Posts: 4,733
    I have two bikes which I race on, one has a compact and the other 53/39 so thats why I go by feel as I would get different ratios using same rear cog :D
    I do tend to use lower gear than most guys sprinting around me.
    Not that I win many other than on the track :(