need help picking out a bike

[Gawnsoft]

On Sat, 02 Oct 2004 22:12:15 GMT, Velvet <[email protected]>
wrote (more or less):

>Daniel Barlow wrote:
>
>> Not unduly excited about the prospect of restarting a tired old
>> thread, but: clipless pedals help a lot, or at least they helped me.
>> The pedalling action was much smoother, and I stopped bouncing
>> around.
>>
>> You may also wish to investigate wearing a helmet, as risk
>> compensation will make you go faster even if you're not aware you're
>> doing it.
>>
>> Er.
>>
>>
>> -dan
>>
>
>LOL Good points - since I can't see me getting out nearly as
>regularly as in the summer (weather AND work conspiracy) I'll slap the
>spuds on the bike and see how that helps the cadence. Will also hack
>slightly at the shoes to see if that solves the unclipping problem. If
>it does, you never know, I might be clipless at some point next summer!
>
>As for helmets - god only knows how slow I'd be if I didn't wear one
>then ;-) Not that I wear one when on the turbo, you understand -
>primarily cos I suspect it'd be of no practical use if I hurtle headlong
>off the turbo into the (possibly wooden) wall or through the
>floor-length (first floor) window...
>
>Then again, maybe I should. Had a couple of near misses when I've
>leaned over when on the turbo to get something - get the weight
>distribution wrong and things get *very* precarious suddenly!

But falling off a stationary bike is exactly what they're designed
for!


--
Cheers,
Euan
Gawnsoft: http://www.gawnsoft.co.sr
Symbian/Epoc wiki: http://html.dnsalias.net:1122
Smalltalk links (harvested from comp.lang.smalltalk) http://html.dnsalias.net/gawnsoft/smalltalk

 

[Just zis Guy, you know?]

On Sun, 3 Oct 2004 01:53:51 +0100, "AndyMorris"
<[email protected]> wrote in message
<[email protected]>:

>> I'm just having trouble understanding how we can apply the force
>> necessary to produce the angular acceleration, without doing any work.

>Force is not the same as work.

That much I know

>My considerable **** is applying a force to my chair, but doing no work.

But in the case of the bike, the force (tractive effort) at the rear
wheel exists solely by virtue of me doing work at the pedals.

It's the scale of the energy loss I'm trying to understand. I rode
round a velodrome last week, and although I wouldn't say I slowed down
much on the bends I definitely went slower.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

 

[Velvet]

Gawnsoft wrote:

>
> But falling off a stationary bike is exactly what they're designed
> for!
>
>

Gah, fell into that trap Oooh, must remember to wear my helmet
whilst posting to usenet! ;-)

Thanks, that inspired a good laugh at this end!

--


Velvet

 

[David Martin]

On 2/10/04 9:49 pm, in article [email protected], "Daniel
Barlow" <[email protected]> wrote:

> Velvet <[email protected]> writes:
>
>> David Martin wrote:
>>> My normal cadence is pretty slow but even I can hit 130+ at a
>>> push.. (OK, a
>>> sprint!)
>>
>> I'm reading this and wondering just *how* you manage it... the most
>
> Not unduly excited about the prospect of restarting a tired old
> thread, but: clipless pedals help a lot, or at least they helped me.
> The pedalling action was much smoother, and I stopped bouncing
> around.

Yes I use clipless. The other thing may be to drop the saddle just a smidgin
(literally a few mm).

Then the trick is to practice. In an easy gear where you have just a slight
resistance, spin up to as fast as you can hold without bouncing. Hold it
there for as long as you can. Think circles, circles, circles. Becasue the
pressure is very light you are not having to concentrate on pushing or
being retarded in the more inefficient parts of the stroke.

Then try sprints where you aim to get the spped up as high as possible,
starting from your fast cadence and not changing gear. Again thinking
circles.

It comes with practice. It is getting your muscles used to that speed. And
then watch the seriously good track riders who can push cadences of near
200.

...d

 

[David Martin]

On 3/10/04 3:53 pm, in article [email protected],
"Just zis Guy, you know?" <[email protected]> wrote:

> But in the case of the bike, the force (tractive effort) at the rear
> wheel exists solely by virtue of me doing work at the pedals.
>
> It's the scale of the energy loss I'm trying to understand. I rode
> round a velodrome last week, and although I wouldn't say I slowed down
> much on the bends I definitely went slower.

<bad physics>
The force does do work in this case because it makes the legs heavier so it
is harder to lift the upstroke on the pedals.. Greater force, greater
distance moved..
</bad physics>

 

[Dave Kahn]

On Sat, 02 Oct 2004 22:36:28 +0900, James Annan
<[email protected]> wrote:

>Just zis Guy, you know? wrote:
>
>
>> So why can't I fly then? :-D
>
>You need to flap harder.
>
>Actually, it is because you have to initially do some work to get in the
>air. Once up there, you'd be ok. I suggest you find a tall building to
>jump out of ;-)

I get the impression that Sandy M. would make a similar suggestion if
he were still around.

--
Dave...

Get a bicycle. You will not regret it. If you live. - Mark Twain

 

[Peter Clinch]

Martin Wilson wrote:

> Yep you've got the right hill. When I look out of the bedroom window
> at night over a basically flat landscape the only thing in the
> distance that can be seen is the lights of cars and lorrys going
> up/down Babylon Hill as if driving to and from space. This is the hill
> alright. Sounds quite impressive to me too, 70m descent over 1000m+

Like I said, it's good, but it's not perfect for speed record attempts.
It doesn't rate a steep hill chevron, for example, which is really
useful for acceleration to terminal velocity, and 1000m given just
freewheel acceleration isn't actually /that/ long a distance.

> At 80rpm cadence on f3,r6 the speed of the cycle computer reads
> 21.7mph
>
> At 100rpm cadence on f3,r6 the speed of the cycle computer reads
> 26.7mph
>
> Logically I would need to momentarily hit a cadence of 112 rpm cadence
> or my own slight downhill momentum to get to 29.7mph.

This is referential to a device which I suspect may be at error though.
You can't check if it's reading right if your basic assumption is that
it's reading right (much like your assuming 7.5 miles to work read off
the computer was useful proof of the speed you were doing).
To check your speed use an external reference and compare that to the
speedo.

> I've already stated that the 30mph was achieved on a slight gradience
> in my favour. Near flat but not flat. So I find it amazing that some
> will accept my 40mph speed and not my 30mph speed claims.

The 40 mph requires the "right hill" in Dave's words. Babylon hill is
good, but there are better about for going Really Fast, both steeper and
longer. Possible you hit 40 on it, but it's not conclusively the "right
hill".
It would help if I knew what your idea of "near flat" is. It might be
steeper, shallower or the same as mine so it might just be easier to
work from something flat so we all know where we stand.

> gearing takes me upto at least 20mph and possibly 24mph with normalish
> cadence so if I'm on a slight downhill section (very slight) and I'm
> cycling with a much faster cadence than normal is it really that
> amazing that I get a peak reading of about 29.7mph?

Going from 20 to 30 will take you 2.25 times as much effort, which isn't
beyond the realms of possibility but supplying that power, even
momentarily, becomes difficult at very high cadences, especially if
you're not attached to the pedals through SPuDs or similar.

Again, it's not impossible and if you /have/ hit that speed then good
work and you owe yourself a round of congratulations: I will happily
munch upon my words! But to be sure the only way is use measurements
completely external to your computer and then compare them to what it
says. Measure the distance to work with a map wheel or a car's
odometer, for example, and see how that compares to your 7.5 miles. If
it reads 7.5 miles too then your speedo will probably be correct.
Get a better bike and lose more weight and you'll be /seriously/ fast.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/