New bike, broken chain.

[Pete Biggs]

The Luggage wrote:
> On 31 Mar, 15:31, David Damerell <[email protected]>
> wrote:
>> Quoting Pete Biggs
>> <[email protected]>:
>>
>>> David Damerell wrote:
>>>> Power, yes, but force? Until you get to pulling up on the bars
>>>> (which admittedly they do), the force one puts through the chain
>>>> is just a matter of chainring size and available lard.
>>> In a sprint, they pull up on the bars to an extreme degree,
>>
>> Extreme compared to ordinary cyclists? Yes. But as a proportion of
>> their body weight? Even the strongest sprinters have tiny arm
>> muscles compared to their leg muscles.
>
> That's irrelevant on two grounds - you don't need huge arm muscles to
> suppport more than your body weight for the few 10s of seconds of a
> sprint. You do need hugh leg muscles to power you through a 200km TdF
> stage. Also, if your elbows are straight, you need virtually no
> muscles to transmit the force from your back to the bars.

That would explain why I can sprint quite well (compared to the average POB
anyway) despite having virtually no arm muscles.

~PB

 

[David Damerell]

Quoting The Luggage <[email protected]>:
>On 1 Apr, 13:24, David Damerell <[email protected]>
>wrote:
>>Quoting =A0The Luggage =A0<[email protected]>:
>>>but you're unlikely to get two lardy tandemmers honking out of the
>>>saddle, each putting their full weight on one pedal in a low gear,
>>Aren't you? Why not? It's perfectly straighforward.
>With complete unweighting of the upward pedal? I'll accept that it is
>possible, but most tandemmers probably won't get close to that sort of
>force on one pedal.

I would think that many tandem teams do get close in that they get to it
minus the weight of two legs (since my experience, admittedly limited to
one particular captain and multiple stokers, is that you can easily climb
with both riders out of the saddle but that pulling on the upward leg is
silly gymnastics).

>2 lardy blokes on a tandem going up a 1:6 hill, using a 34 tooth rear
>cog. Total mass 250 kg. Forward force required =3D 2500/6 =3D 416N.
>26" (660mm) wheel and 72mm cog diam give an average chain tension of
>1.9 kN.

And manifestly people do ride tandems up 1:6 hills.
--
David Damerell <[email protected]> Oil is for sissies
Today is Second Teleute, April.

 

[[email protected]]

On Apr 1, 6:54 pm, The Luggage <[email protected]> wrote:
> The tandemmers have weight and low gearing, but
> won't use their full weight on the pedals.

Some of us certainly do (on occasion).

James