Silly commuting racing

tgotb

mamil314 wrote:

Is this right? I thought bodyweight was not a limit?

if single.leg.squat > 2 x bodyweight
then begin stay_in_seat_and_hold_bars_tight;
crush pedals(much);
print ('Next Red Light Already?!'); end;
else if gym_member=true then deadlift(much);
else get_fixie=true;

Knees might not like it.

How much do you *actually* pull up on the bars and opposing pedal though? Enough to nose ahead of someone who's not doing it, but I suspect nothing like enough to increase your power by 50%. In any case, anything you can do at 80rpm will also work (with a bit more practice) at 120rpm.

You'll never see Cav mashing the pedals in a sprint. Hoy does (did), but he doesn't have gears. Or watch the start of a pro CX race; spinny, not grindy...

rower63

TGOTB wrote:

njee20 wrote:

rower63 wrote:

njee20 wrote:

Always big ring for starting off! 34-23 is far too spinny after about half a pedal stroke! Makes clipping in less predictable too as your pedals are more likely to spin around. Decent lead stroke, catch the pedal nicely as it comes up to 12 o clock and you're away, whilst all the inner-ring folk are still looking down at their pedals and destroying front mechs with painful shifts!

I used to think the same until I once very quickly found myself 25m behind TGOTB from level standing start at the Vaux Bridge junction when I thought I was being quick off the mark. That learned me.

Not knowing TGOTB beyond a forum pseudonym, but having never consciously ended up very quickly 25m behind someone from a standing start I'm happy with my technique ;-)

'tis basic physics. You can only apply a limited torque (roughly speaking, your weight multiplied by your crank length), so the only way to get more power down is to increase your rpm. Your 52x21 is 50% longer than my 34x21, which means you're doing 2/3 the cadence and therefore limited to 2/3 the power, and 2/3 the acceleration.
Clipping in shouldn't be a problem in any gear; you probably practice it 100 times per day, so there's no excuse not to nail it first time. As for the shift to big ring, that can happen well beyond 20mph, so there's ample opportunity to soft-pedal for half a revolution without losing much of the distance you've gained.

To give an analogy: It's a bit like pulling away from the lights with your car in third gear. Yes, you can do it; yes, you waste less time changing gear; it's still not as pulling away in first.

I think of it from a slightly different angle, but making the exact same point as TGOTB.
The key basic physics is that Power = torque x revs. (and more power means more speed).
When you’re going along working hard close to your limit at 27mph, you’re likely well within your maximum torque and your revs might be, say, 100rpm. You’re pushing 400W and you might blow up soon. Your power output is your limiting factor.
From a standstill, it’s different. A moment after you set off, your revs will be very low, and your torque will be your maximum. Even your maximum torque multiplied by your (very low) revs will give a momentary power output that will be well below your maximum (because the revs are so low). In other words, your limiting factor from a standing start is your pure strength, not your power. If you’re already at max strength (or torque), you must try to increase your revs as much as possible.
In other words, you need as low a gear as you can manage for the quickest standing start.

njee20

Define manage in the context of lower gears? Obviously you can manage them... Would 22/50 be fastest then? My peak power on a normal ride (or a race FWIW) will generally be in the 2-3 seconds following a standing start, so yes, as I said, I agree that between 0-2mph smaller gear probably is faster, but as we don't stop accelerating at 2mph that seems a moot point, and I'll compromise my acceleration in that phase in order to reach speed quicker.

Or watch the start of a pro CX race; spinny, not grindy...

But that's the point, I'm not grinding, obviously I'm using a very similar gear to that which I'd use for a race start, and that's not my smallest. Find anyone starting a CX race in their bottom gear.

elbowloh

What about wind resistance?

;-)

tgotb

njee20 wrote:

Speaking as someone who's led out a lot of mountain bike races, and never once from my easiest gear! ;-)

If we really want to get into willy waving, I've taken the holeshot in a lot of CX races, and always from an easy gear (generally 38x25). Can be a bit wheel-spinny on slippery mud though, so try it beforehand and pick a higher gear if there's not enough traction.

njee20 wrote:

You also suggest that the heavier a person is the quicker they'll get off the line, as more bodyweight = more torque, and clearly that's nonsense.

Nope. I'm saying that your torque is limited by your bodyweight. Your power is the product of your torque and your cadence. Once you're standing on the pedals, the only things you can do to increase your power are:
1. Get heavier
2. Get longer cranks
3. Change to an easier gear

More bodyweight does allow you to get more power down, but you also have more mass to accelerate, so it (roughly - let's ignore the weight of the bike) cancels out.

Thought experiment: If you go somewhere where gravity is stronger, you'll be heavier but your mass will be the same; you should be able to accelerate more quickly (but the hills will be horrible).

tgotb

elbowloh wrote:

What about wind resistance?

;-)

Inversely correlated with bodyweight. Hot air generated by internet forum discussions will also be a factor; hot air is less dense than cold air, but we don't know which way it's moving...

tgotb

njee20 wrote:

Define manage in the context of lower gears? Obviously you can manage them... Would 22/50 be fastest then? My peak power on a normal ride (or a race FWIW) will generally be in the 2-3 seconds following a standing start, so yes, as I said, I agree that between 0-2mph smaller gear probably is faster, but as we don't stop accelerating at 2mph that seems a moot point

Assuming a target cadence of 90rpm, by the time you get on top of a 52x21 gear you're doing about 16mph

njee20 wrote:

I'll compromise my acceleration in that phase in order to reach speed quicker.

Erm...???

Try it out, you might find your starts get even better!

rower63

njee20 wrote:

Define manage in the context of lower gears?

there comes a point where too low a gear means you move so quickly your muscle-contraction can't maintain contact at your max pressure; and the need to change gear comes into it too: gear-changing takes a bit of time, so you need to choose the lowest gear that you can reach, say, 25mph at your max revs for when you first change. Those are details, though: the main point is that off the start you can't change the max torque you can exert, you can change the gearing: you need to go as low as you "can".

hopkinb

TGOTB wrote:

Try it out, you might find your starts get even better!

I'm trying it later. If I ship my chain or whack myself on the top tube, I shall be silently cursing your name.

34/21 you say?

rower63

hopkinb wrote:

TGOTB wrote:

Try it out, you might find your starts get even better!

I'm trying it later. If I ship my chain or whack myself on the top tube, I shall be silently cursing your name.
34/21 you say?

I don't think so

mamil314

Thanks for advice. On the fixie i am putting together, i will put 48x19 for a ((very)short lived) glory.

tgotb

rower63 wrote:

njee20 wrote:

Define manage in the context of lower gears?

there comes a point where too low a gear means you move so quickly your muscle-contraction can't maintain contact at your max pressure; and the need to change gear comes into it too: gear-changing takes a bit of time, so you need to choose the lowest gear that you can reach, say, 25mph at your max revs for when you first change. Those are details, though: the main point is that off the start you can't change the max torque you can exert, you can change the gearing: you need to go as low as you "can".

So you're saying you only do one change? Interesting; I assume that's a front ring shift?

I have a different technique: Start in "3rd", and then do a double shift each time I spin out. Assuming I top out at 120rpm (which is a guess), that would have me doing my first change at ~15mph, then again at ~19mph, and once more at ~22mph. If I'm really trying, that'll take me up to 25-26mph, at which point I sit down and shift to the big ring.
Broadly speaking, that's the technique I was taught by our CX coach, albeit the CX bikes have single chainrings and wider-spaced cassettes. On the CX bike that'll take me up to just over 30mph on a tarmac start straight (which is quite alarming with the tyres at 18psi...)

elbowloh

Guys.

it's only a commute...


;-)

njee20

Wasn't willy waving, merely providing context, again, I've not a clue who you are, so it would be extremely remiss to suggest I'm in any way better than you! You could be Tom Pidcock for all I know!

I'm mildly interested in experimenting, 34/21 just feels far too low! You have made me delve into old data files though, generally seems I'm up to about 105rpm in ~3 seconds, with power at that point around about 600w. My 2 minutes of digging didn't yield any efforts where I know I tried hard, so it's a blind test, but not necessarily representative of "what's fastest".

smokey_bacon

rower63 wrote:

hopkinb wrote:

TGOTB wrote:

Try it out, you might find your starts get even better!

I'm trying it later. If I ship my chain or whack myself on the top tube, I shall be silently cursing your name.
34/21 you say?

I don't think so

rower63

TGOTB wrote:

rower63 wrote:

njee20 wrote:

Define manage in the context of lower gears?

there comes a point where too low a gear means you move so quickly your muscle-contraction can't maintain contact at your max pressure; and the need to change gear comes into it too: gear-changing takes a bit of time, so you need to choose the lowest gear that you can reach, say, 25mph at your max revs for when you first change. Those are details, though: the main point is that off the start you can't change the max torque you can exert, you can change the gearing: you need to go as low as you "can".

So you're saying you only do one change? Interesting; I assume that's a front ring shift?...

Yes if I'm doing a really serious start, such as the Millbank sprint , I start in something like 39/19 and spin out to 130+, and my front-change is the first. I've noticed 800-900W at those max revs before the change. Thereafter I'm in more normal rear-change mode.

dekant

Guys, Guys, Guys! There's only one way to settle this...

...and that's a SCR standing start drag race. See you all on Southwark bridge road at sundown!

elbowloh

dekant wrote:

Guys, Guys, Guys! There's only one way to settle this...

...and that's a SCR standing start drag race. See you all on Southwark bridge road at sundown!

I can hear Fleetwood Mac's The Chain right now.

njee20

I'd actually be up for that! One where we have to try each other's gear combinations too!

I can see Southwark Bridge Road from my desk, but sod waiting until sundown, I'll be on Millbank at 5:45 :-)

tgotb

njee20 wrote:

I'd actually be up for that! One where we have to try each other's gear combinations too!

I can see Southwark Bridge Road from my desk, but sod waiting until sundown, I'll be on Millbank at 5:45 :-)

:-)
This is the real answer. I'm afraid I'm WFH today (racing at Hillingdon tonight) but there will be other days.

Not at sundown though, that's almost my bedtime!

dekant

TGOTB wrote:

Not at sundown though, that's almost my bedtime!

Dawn?

abbster

hopkinb wrote:

Hello abbster, yep, that was me on the ti bike . I normally turn off and take Southwark bridge, but was having too much fun definitely probably racing, so carried on to E&C & beyond. I'll say hi if our paths cross again.

Was a lot of fun.. you're quick! A pleasure to definitely probably race you, yes do say hi next time

njee20

dekant wrote:

TGOTB wrote:

Not at sundown though, that's almost my bedtime!

Dawn?

Maybe in November, I have to get up earlier than I want to get in for 8:15!

hopkinb

Took until Balham for me to stop shivering - got too used to this warm sunshine. Hence a slow ride in, confirmed when I got a cheery good morning from abfg mugging me off round the outside while I dawdled behind a lorry on the lower slopes of Southwark bridge.

kingdav

I did a long commute today rather than my half car usual thing. Over the ridge at Tandridge Hill and whilst elevated through to Warlingham it was very misty and damp which was a bit a of a surprise. Very glad of the arm warmers.

anonymousblackfg

hopkinb wrote:

Took until Balham for me to stop shivering - got too used to this warm sunshine. Hence a slow ride in, confirmed when I got a cheery good morning from abfg mugging me off round the outside while I dawdled behind a lorry on the lower slopes of Southwark bridge.

Should that post not be in the Silly Commuting Dawdling thread? I forgot to reply to your comment about my Wimbledon route, I think it's quicker than dirty Tooting on the way home and much more pleasant (Plough Lane excluded).

A decent ride in, again I came across little fixie pannier man, surprisingly quick so I needed keep pushing.

hopkinb

anonymousblackfg wrote:

Should that post not be in the Silly Commuting Dawdling thread? I forgot to reply to your comment about my Wimbledon route, I think it's quicker than dirty Tooting on the way home and much more pleasant (Plough Lane excluded).

Yeah, I tried it & liked it, except for plough lane, which was grotty with traffic, but probably less grotty than tooting.

I also tried small ring acceleration last night - I did not like it, and got burned off by some chopper on a flat bar bso. 34 tooth small ring is just too small, and shifting from 34/13 to 50/13 was a bit of a shock. I think my normal 50/23 starting gear is quite similar to rower's 39/18.

frogonabike

I tried out some different gears to usual when pulling away this morning and I think lower may actually be the way plus it's definitely easier on the knees! It took a bit to get my head around it as I'm used to doing standing starts on the track with a 90"+ gear

I was on 1x today so went for 46x28 (I think that's the nearest I have to what you guys were talking about) and I felt okay spinning for a fair bit longer than expected before shifting up. I also find the bigger jumps of a 36-11 cassette are good for accelerating as I don't feel the need to double shift and only having one ring up front simplifies things!

I'd like to try some timed runs but almost definitely can't be bothered. If I bump into one of you then I'll happily have a wee drag race or 2 to test it...

roger_merriman

Pulling smartly away from the lights, will depend I assume on person to person.

I’m generally quick off the mark, in that I find most people painfully slow off the mark, i tend to gear down, and shift up as needed this does depend on how high you can spin, I did have a SS so can spin.

Since I’m hot and bothered and thus mildly grumpy I’ll point out that for most roadies Learning how to clip in quickly would probably be the most beneficial, I’m always staggered how many are click-click-click etc as they are crossing the junction.

hopkinb

Nice chat on the way home with a guy I've seen on the cs7 segment leaderboards. Clueless fcukers all rushing home for football made things more dangerous than usual.