Radical gearing change: advice needed...

[David Damerell]

Quoting Bonge Boo <[email protected]>:
>David Damerell wrote:
>>Quoting Bonge Boo <[email protected]>:
>>>But as soon as the incline goes beyond 3-4%, frankly that makes no
>>>difference. And when you get to 10%+ its so irrelevant.
>>Uh - as distinct from the psychosomatic effects, it's exactly on a steep
>>incline where weight matters.
>Err. How so? I weigh 150lbs. Bikes weight between 22lb and 29lbs. As a
>proportion that's sod all.
>Unless my basic physics it wrong, the work required to lift that mass is
>only about 5% more.

Yes. On the flat the work required to drive that mass is about 0% more. It's
more relevant the steeper the incline; "when you get to 10%+ its (sic) so
irrelevant" is exactly the wrong way around.
--
David Damerell <[email protected]> flcl?
Today is Olethros, August - a weekend.

 

[Rob Morley]

In article <Xol*[email protected]>, David Damerell
[email protected] says...
> Quoting Rob Morley <[email protected]>:
> >[email protected] says...
> >>Also - if you get down to walking speed, may as well walk (on a solo).
> >Why do you say that? When you're on a bike most of your leg effort goes
> >into propulsion, but when you're walking most goes into keeping your bum
> >off the ground and moving your legs.
>
> That's very true on the flat. It's not so true when you are trying to do
> work against gravity, and when staying on the bike requires low-speed
> steering effort.
>
But still quite true?

 

[David Damerell]

Quoting Rob Morley <[email protected]>:
>[email protected] says...
>>That's very true on the flat. It's not so true when you are trying to do
>>work against gravity, and when staying on the bike requires low-speed
>>steering effort.
>But still quite true?

No, I don't think so. My perception (and yes, this is just perception) is
that once I get down to 3mph on the bike I'm utterly miserable and won't
be any more bushed if I dismount and walk.
--
David Damerell <[email protected]> flcl?
Today is Olethros, August - a weekend.

 

[Peter Clinch]

David Damerell wrote:

> No, I don't think so. My perception (and yes, this is just perception) is
> that once I get down to 3mph on the bike I'm utterly miserable and won't
> be any more bushed if I dismount and walk.

The nice thing about walking, of course, is no real work is needed to
prevent you from rolling backwards, so you can rest at will as part of
the walking action. Not so on the bike.

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/

 

[Ace]

On Wed, 22 Aug 2007 12:19:28 +0100, Peter Clinch
<[email protected]> wrote:

>David Damerell wrote:
>
>> No, I don't think so. My perception (and yes, this is just perception) is
>> that once I get down to 3mph on the bike I'm utterly miserable and won't
>> be any more bushed if I dismount and walk.
>
>The nice thing about walking, of course, is no real work is needed to
>prevent you from rolling backwards, so you can rest at will as part of
>the walking action. Not so on the bike.

Absolutely. As I've mentioned before I've had severe back problems
(m/bike accident and subsequent surgery) which have limited my fitness
for the last year. The drive to our house is about a 1:5 at its
steepest point (for about 10 metres), and in my unfit state there's no
way I could cycle up it, regardless of gear. The limiting factor was
the strain it puts through the back, as well as overall
breathlessness.

Walking up the same hill still required effort, but I could go as slow
as I liked, including standing still if required, with the net result
of being much less out of breath and in pain at the top.

So was the overall work done less when walking? Yes, I believe so, as
it only took perhaps 50% longer than cycling and with much less
intense effort.

--
Ace in Alsace - brucedotrogers a.t rochedotcom

 

[Bonge Boo]

David Damerell wrote:
> Quoting Bonge Boo <[email protected]>:
>> David Damerell wrote:
>>> Quoting Bonge Boo <[email protected]>:
>>>> But as soon as the incline goes beyond 3-4%, frankly that makes no
>>>> difference. And when you get to 10%+ its so irrelevant.
>>> Uh - as distinct from the psychosomatic effects, it's exactly on a steep
>>> incline where weight matters.
>> Err. How so? I weigh 150lbs. Bikes weight between 22lb and 29lbs. As a
>> proportion that's sod all.
>> Unless my basic physics it wrong, the work required to lift that mass is
>> only about 5% more.
>
> Yes. On the flat the work required to drive that mass is about 0% more. It's
> more relevant the steeper the incline; "when you get to 10%+ its (sic) so
> irrelevant" is exactly the wrong way around.

No its not. The extra efficiency of the machine is more than outweighed
by the silly gearing. Give me a decently geared but heavy bike compared
to a super lightweight whatever with silly gears.

On the flat the gearing is less of an issue. As soon as it gets vertical
the gearing becomes the over-riding limitation of any vehicle, car or
bike. Car's have a damn site more power than people. We still put gears
on them.

Try riding your Madone 5.9 up a 15% climb on a 39-25. You will struggle.
Try the same thing of some fat pig of an MTB with a 28-30. You'll
happily spin up.

Racers might be obsessed with weight, but normal people need gears. Not
titanium or carbon.

 

[David Damerell]

Quoting Bonge Boo <[email protected]>:
>David Damerell wrote:
>>Yes. On the flat the work required to drive that mass is about 0% more. It's
>>more relevant the steeper the incline; "when you get to 10%+ its (sic) so
>>irrelevant" is exactly the wrong way around.
>No its not. The extra efficiency of the machine is more than outweighed
>by the silly gearing.

Total distraction. We were talking about the rolling resistance and weight
- your words - which you claimed became irrelevant uphill. In fact they
are largely irrelevant on the flat.
--
David Damerell <[email protected]> Distortion Field!
Today is First Monday, August.

 

[M-gineering]

David Damerell wrote:

> Total distraction. We were talking about the rolling resistance and weight
> - your words - which you claimed became irrelevant uphill. In fact they
> are largely irrelevant on the flat.

you're either joking or trolling
--
/Marten (knows about flat!) Gerritsen

info(apestaartje)m-gineering(punt)nl

 

[David Damerell]

Quoting M-gineering <[email protected]>:
>David Damerell wrote:
>>Total distraction. We were talking about the rolling resistance and weight
>>- your words - which you claimed became irrelevant uphill. In fact they
>>are largely irrelevant on the flat.
>you're either joking or trolling

Er... neither. On the flat weight makes no difference at all except under
acceleration. RR, short of knobblies/no knobblies [1], just isn't very
relevant at all - on the flat because of how aero grows exponentially with
speed, and uphill because you're going slug slow anyway.

[1] Or similar. You _can_, yes, get it wrong on RR, but the difference
between OK and perfect is not great.
--
David Damerell <[email protected]> Distortion Field!
Today is First Tuesday, August.

 

[[email protected]]

On 22 Aug, 22:34, Bonge Boo <[email protected]> wrote:

> On the flat the gearing is less of an issue. As soon as it gets vertical
> the gearing becomes the over-riding limitation of any vehicle, car or
> bike. Car's have a damn site more power than people. We still put gears
> on them.

I'm going to approximate a lot- don't get picky...

Firstly- not all vehicles have gears- electric traction motors don't
need them for a start (pun intended, DWI .

Cars (at least, conventional IC ones) produce no torque at
standstill, and only work at all in quite a narrow rpm range, say 500
to 5000, approximating to orders of magnitude).

Cyclists have a wider range of useful revs (0-100, two orders of
magnitude instead of one). OTOH, peak performance is at a limited
range and there are significant benefits to achieving it.

IMHO, it's more fun riding a light bike with no gears than a heavy
bike with lots. YMMV, of course...

> Racers might be obsessed with weight, but normal people need gears. Not
> titanium or carbon.-

Lots of normal people have managed quite happily without gears for
quite a lot of the time... mind you, they managed without titanium or
carbon, either
At any rate- can we agree that the easiest bike to ride uphill is a
light one with low gears, and focus on how to acheive that cheaply...
I liked the double to triple conversion ring idea, personally, as this
would give you a couple of granny gears without mucking about too much
with the rest of the system. OTOH, if the wide-range cluster works and
an LBS will engineer it for you, then so much the better!

Cheers,
W.

 

[David Martin]

On 20 Aug, 12:33, Ace <[email protected]> wrote:
> On Mon, 20 Aug 2007 12:14:28 +0100, Bonge Boo <[email protected]>
> wrote:
>
>
>
> >Rob Morley wrote:
> >> In article <[email protected]>, Bonge Boo
> >> [email protected] says...
> >> <snip>
> >>> Help! Any suggestions gratefully received.
>
> >> Something like this?
> >>http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300141789355
> >> There are a few other rings for this on eBay ATM, including 40 and 42
> >> tooth.
> >> I run 32/44 on 12/26 with Ultegra mechs with no problems, but with 28/45
> >> you'd probably have to get the chain length spot on and be careful to
> >> avoid the big/big and small/small combinations. The front mech will
> >> probably be on its limits too.
>
> >Would this work with STI shifters? As I (maybe mistakenly) thought that
> >the shifter/derailleur was designed to work with certain size
> >chainrings. As they don't use friction shift at the front, I'm a little
> >wary of playing.
>
> The chainring size is irrelevant to the shifter and derailleur
> function, provided they're properly set up, of course.

That is not true. A compact-specific mech will work much better on
the front than a standard one. The standard one will work, but not
well. moving to a mirage compact front mech (on RSX shifters) works
fine.

I have done the conversion so can speak from experience. A compact
chainset is the way to go, especially as you can put bigger rings on a
small spider but not the other way round. I have a TA carmina in
48/34. Not cheap but very nice.

Going to a triple will cost around 60-70 quid for something like a
stronglight impact chainset and possibly a new bottom bracket if it is
needed. (Spa cycles are good people) All the shimano STI of that era
should be capable of taking a triple - just need to be set up right.

> >I assume if I get a compact drive chainring I could use a 13 tooth
> >difference (as the current is a 52x39). Then it's just a question of
> >dropping the front derailleur down to the correct height on the seat-tube?
>
> Proper setup may include moving the front derailleur mechanism further
> down the tube such that it spans the two chain heights, which will
> clearly be lower if you use smaller chainrings. But the size
> difference between them is not critical, so you could go for a larger
> or smaller range between the two rings with no ill effect.

The key difference is the shape of the sideplates (and getting the
mech at the right height). I spent ages finding a suitable triple mech
for my MTB as all the MTB ones wouldn't cope nicely with a 48t big
ring (but liked 42t).

As far as the rear cassette goes, you probably can't fit a larger
cassette unless you have a long cage mech, otherwise the difference in
chain length will be too much and you will risk damage at the extreme
combinations.

...d

 

[David Martin]

On 24 Aug, 10:53, David Martin <[email protected]> wrote:
> On 20 Aug, 12:33, Ace <[email protected]> wrote:
>
>
>
> > On Mon, 20 Aug 2007 12:14:28 +0100, Bonge Boo <[email protected]>
> > wrote:
>
> > >Rob Morley wrote:
> > >> In article <[email protected]>, Bonge Boo
> > >> [email protected] says...
> > >> <snip>
> > >>> Help! Any suggestions gratefully received.
>
> > >> Something like this?
> > >>http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=300141789355
> > >> There are a few other rings for this on eBay ATM, including 40 and 42
> > >> tooth.
> > >> I run 32/44 on 12/26 with Ultegra mechs with no problems, but with 28/45
> > >> you'd probably have to get the chain length spot on and be careful to
> > >> avoid the big/big and small/small combinations. The front mech will
> > >> probably be on its limits too.
>
> > >Would this work with STI shifters? As I (maybe mistakenly) thought that
> > >the shifter/derailleur was designed to work with certain size
> > >chainrings. As they don't use friction shift at the front, I'm a little
> > >wary of playing.
>
> > The chainring size is irrelevant to the shifter and derailleur
> > function, provided they're properly set up, of course.
>
> That is not true. A compact-specific mech will work much better on
> the front than a standard one. The standard one will work, but not
> well. moving to a mirage compact front mech (on RSX shifters) works
> fine.
>
> I have done the conversion so can speak from experience. A compact
> chainset is the way to go, especially as you can put bigger rings on a
> small spider but not the other way round. I have a TA carmina in
> 48/34. Not cheap but very nice.
>
> Going to a triple will cost around 60-70 quid for something like a
> stronglight impact chainset and possibly a new bottom bracket if it is
> needed. (Spa cycles are good people) All the shimano STI of that era
> should be capable of taking a triple - just need to be set up right.
>
> > >I assume if I get a compact drive chainring I could use a 13 tooth
> > >difference (as the current is a 52x39). Then it's just a question of
> > >dropping the front derailleur down to the correct height on the seat-tube?
>
> > Proper setup may include moving the front derailleur mechanism further
> > down the tube such that it spans the two chain heights, which will
> > clearly be lower if you use smaller chainrings. But the size
> > difference between them is not critical, so you could go for a larger
> > or smaller range between the two rings with no ill effect.
>
> The key difference is the shape of the sideplates (and getting the
> mech at the right height). I spent ages finding a suitable triple mech
> for my MTB as all the MTB ones wouldn't cope nicely with a 48t big
> ring (but liked 42t).
>
> As far as the rear cassette goes, you probably can't fit a larger
> cassette unless you have a long cage mech, otherwise the difference in
> chain length will be too much and you will risk damage at the extreme
> combinations.
>
> ..d

Having made it through to the end of the thread, the megarange
cassette and new rear mech is by far the best solution. Easily
compatible, and will give you the best of both worlds.

Gears/weight/speed. If you want to get up a hill at X speed then you
will need a certain gear to be able to do it in relative comfort. The
lighter the bike, the more comfortable in that gear. I have ridden up
some not particularly sttep but still noteworthy hills (Carter Bar for
one) on a fully loaded touring bike. It would have been a lot easier
to ride my unladen road bike up there at three times the speed.

...d