Bike Weight -- uphill TT

Art M said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight will give you virtually nil advantage in the real world.
Aero-dynamics and fitness are what improve time-trials.
To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.
See this site for some ideas:
http://www.softride.com/bike/triAero.asp
There are loads of other sites detailing the same sort of thing.
Alan.

--
To reply by e-mail, change the ' + ' to 'plus'.
http://www.dvatc.co.uk - Off-road cycling in the North Midlands.

"A.Lee" <alan@darkroom.+.com> wrote in message
news:[email hidden]...

Quoted message said:

Art M said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a

26.5

Quoted message said:

Quoted message said:

lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction

in

Quoted message said:

Quoted message said:

overall weight)?

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight will give you virtually nil advantage in the real world.
Aero-dynamics and fitness are what improve time-trials.
To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.
See this site for some ideas:
http://www.softride.com/bike/triAero.asp
There are loads of other sites detailing the same sort of thing.
Alan.

I'm about to check out your link, but bear in mind that this was just uphill
(the complete course was 7 miles long, all uphill -- ave grade ~8%, 20% max,
my ave speed a bit over 8 mph). Are you telling me that at that speed bike
weight (when climbing) matters less than aerodynamics?

--Art

"A.Lee" <alan@darkroom.+.com> wrote in message
news:[email hidden]...

Quoted message said:

Art M said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a

26.5

Quoted message said:

Quoted message said:

lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction

in

Quoted message said:

Quoted message said:

overall weight)?

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight

ALSO, it's a 10 lb reduction in bike weight (many bikes these days are a bit
over 16 lbs, no?) resulting in a 5% reduction in rider+bike weight.

--Art

A.Lee alan@darkroom.+.com said:

On Mon, 03 May 2004 14:21:23 +0000, Art M wrote:

Quoted message said:

Quoted message said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

Quoted message said:

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight will give you virtually nil advantage in the real world.
Aero-dynamics and fitness are what improve time-trials.
To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.

That's daft. You don't need aerodynamics on a 7 mile, 8% all uphill TT.

His bike already weighs 26.5 lbs. An 18 lb bike would definitely make a significant improvement.

To the OP: Try www.analyticcycling.com

Art Harris

Art M said:

"A.Lee" <alan@darkroom.+.com> wrote in message
news:[email hidden]...

Quoted message said:

Art M said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a
26.5lb bike. Does anyone have a formula that would tell me how much
my time would have improved on a competitive bike (resulting in a ~5%
reduction in overall weight)?

Basically, the 5% reduction (1.5lb?) in bike weight will give you
virtually nil advantage in the real world. Aero-dynamics and fitness
are what improve time-trials. To get your bike faster, get some aero
wheels, which may actually make your bike heavier, but the bike will go
faster, even on a 7mile 8% hill over 26miles.

I'm about to check out your link, but bear in mind that this was just
uphill (the complete course was 7 miles long, all uphill -- ave grade
~8%, 20% max, my ave speed a bit over 8 mph). Are you telling me that at
that speed bike weight (when climbing) matters less than aerodynamics?

Sorry, I read it as a 7 mile climb during a 26mile TT.
Go to :http://www.analyticcycling.com/WheelsClimb_Page.html
and type in all your details.I've just tried it, with a 65kg rider, and a
1kg difference in 2 bikes, the 1kg bike comes out as 27seconds faster over
10000metres,on a straight 8% climb.
Alan.

--
To reply by e-mail, change the ' + ' to 'plus'.
http://www.dvatc.co.uk - Off-road cycling in the North Midlands.

No problem. I've made hasty replies before myself.

--Art

"Harris" <[email hidden]> wrote in message
news:[email hidden]...
-snip-

Quoted message said:

His bike already weighs 26.5 lbs. An 18 lb bike would definitely make a

significant improvement.

Quoted message said:

To the OP: Try www.analyticcycling.com

Art Harris

Thanks. I get a lot of ribbing about my bike. This is one case where I was
sure it hindered me, but I didn't want to overestimate it.

It looks like at a power output of 250 to 200 watts I might have seen a 2 to
3 minute improvement. That would have moved me up the ranks.

--Art

Art M said:

Thanks. I get a lot of ribbing about my bike. This is one case where I was
sure it hindered me, but I didn't want to overestimate it.

It looks like at a power output of 250 to 200 watts I might have seen a 2 to
3 minute improvement. That would have moved me up the ranks.

It was wet last Thursday so I rode my touring bike in the club "10".
It's a flat course so the extra 10lb weight didn't make much difference,
but aerodynamically it's tragic (fenders, rack, lights and three bottle
cages) and the big fat wheels don't help either. I was only 6 seconds
slower than on my racing bike. I suppose the moral is that the rider,
and how well he/she feels on the day, is more important.

Quoted message said:

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?)

Read the original post more carefully - the Op clearly means 5% of
bike and rider, which is a lot more than 1.5lb. Figure that we are
talking 8lb difference between the OP's 26.5lb clunker and a
reasonably light road bike.

Quoted message said:

To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.
See this site for some ideas:
http://www.softride.com/bike/triAero.asp

The figures at the above link show the opposite of what you claim
(using your figures, 1.5lb is not important). To quote: "Only when the
grade exceeds 3.7 percent does the bike with lighter [by 400g, which
is about 1lb] wheels have the advantage".

--
Peter Headland

"Art M" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

--Art

You haven't given enough info to determine this:
(1) what was your overall time ?
(2) what's your height and weight ?

An an estimate you'd go ~ 5 % faster (I'd say about a 2 minutes
improvement in your time).

On 3 May 2004 11:59:09 -0700, [email hidden] (Peter Headland)

Quoted message said:

Quoted message said:

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?)

Read the original post more carefully - the Op clearly means 5% of
bike and rider, which is a lot more than 1.5lb. Figure that we are
talking 8lb difference between the OP's 26.5lb clunker and a
reasonably light road bike.

Quoted message said:

To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.
See this site for some ideas:
http://www.softride.com/bike/triAero.asp

The figures at the above link show the opposite of what you claim
(using your figures, 1.5lb is not important). To quote: "Only when the
grade exceeds 3.7 percent does the bike with lighter [by 400g, which
is about 1lb] wheels have the advantage".

Dear Peter,

While the effect of a small amount of weight is small, it's still an
effect. Given the same force, heavier objects accelerate more slowly .
Increased weight also increases rolling resistance. Technically,
adding a postage stamp will have a postage-stamp sized effect.

To take the 1.5 pound example, assume a light bicycle and rider that
weigh only 150 pounds. The pound-and-a-half is only 1%, so we he-man
types at rec.bicycles.tech usually dismiss it as negligible and
snicker at the anorexic mind-set of so many racers.

But 1% of a century ride is 5,280 feet--three minutes at 20 mph. And
Armstrong keeps winning the Tour de France by less than 10
minutes--less than 0.2% in 5,000+ minutes of racing.

In horse-racing, where far more power is available than in bicycling,
overall weight is far greater, much more money is at stake, and what
might be politely called irregularities are not unknown, the officials
still find it worth the trouble to weigh the jockeys and their saddles
to within a pound, before and after the race:

Weighed in

All jockeys are weighed (with their saddles) before a race to ensure
they are carrying the correct weight - this is known as "weighing
out". After the race, jockeys who have ridden a horse that is placed
must then "weigh in". They must not weigh in at more than a pound less
than they weighed out.

http://news.bbc.co.uk/sport1/hi/other_sports/horse_racing/2964325.stm

Me, I carry four spare tubes and a spare tire on a fifteen-mile ride.
I suspect that they slow me down.

Carl Fogel

"Art M" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

--Art

Unless you are a VERY light rider or you have a VERY heavy bike, you
can not achieve a 5% reduction in overall weight from your bike alone.

If you calculate the % reduction in overall weight (rider and bike)
achieved by a reasonable reduction in the bike weight, you'll see that
it's not a big deal.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"Art M" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

--Art

Unless you are a VERY light rider or you have a VERY heavy bike, you
can not achieve a 5% reduction in overall weight from your bike alone.

A 170lb rider dropping from a 28lb bike to an 18lb bike will drop more
than 5% of total weight.

--
Remove the ns_ from if replying by e-mail (but keep posts in the
newsgroups if possible).

Quoted message said:

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight will give you virtually nil advantage in the real world.
Aero-dynamics and fitness are what improve time-trials.
To get your bike faster, get some aero wheels, which may actually make
your bike heavier, but the bike will go faster, even on a 7mile 8% hill
over 26miles.

Hi Alan,

Your note reminded me of an article I read in Bicycling Magazine. I
found the issue I had in mind, it's September, 2003. I remembered it
as I need to lose weight. It's from an article on improving uphill
performance. For what it's worth I'll mention it here:

SPANK YOUR BAD SELF (basically saying - lose weight):
Here's the difference losing - or gaining - weight will make on a 5 km
(3.1 mile) climb with an avg grade of 7%, assuming you put out an avg
of 250 watts. Even if your power never increases, you climb about 30
seconds faster per 5 km for every 5 pounds lost. Calculations
performed for BICYCLING by James C. Martin, Ph.D., assistant professor
in the department of exercise and sport science at the University of
Utah.

Cheers (with diet pop),

Neil

Quoted message said:

... course was 7 miles long, all uphill -- ave grade ~8%, 20% max, my
ave speed a bit over 8 mph).

On steep climbs where speeds are low, the resistive force is primarily
gravity and your speed will be very nearly proportional to power/weight.
So if you drop 5% of your total weight, and you maintain the same power,
speed will go up by about 5% and you will drop about 5% off your time.

For more exact numbers that include air resistance and rolling
resistance, use www.analyticcycling.com

--

arthur-<< I just completed an uphill time trial approx. 8% grade for 7 miles on
a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)? >><BR><BR>

5% reduction of overall weight??you and your bike??

That's about a 10 pound reduction(assuming you weigh 170 pounds)...Anyway, less
than 5% improvement. Less weight improvement is not linear, assuming all else
is equal, ride to ride, and it never is.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Peter Chisolm said:

Less weight improvement is not linear, assuming all else
is equal, ride to ride, and it never is.

It is linear if the grade is steep enough, where almost all the
effort goes into lifting meat up the hill.
--
terry morse Palo Alto, CA http://bike.terrymorse.com/

A.Lee alan@darkroom.+.com said:

Art M said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

This has been done to death many times before here, for the various
threads, do a Google groups search.Basically, the 5% reduction (1.5lb?) in
bike weight will give you virtually nil advantage in the real world.

Not uphill, where a lot - even the majority - of effort is going into
overcoming gravity. In an extreme case a 5% reduction in overall weight
(not bike weight) might produce a nearly 5% increase in speed, although an
8% grade isn't it.

We can't, however, produce an estimate without knowing how fast the OP
went, since power to overcome gravity is linear with speed, but to
overcome air resistance power varies with the cube of speed.
--
David Damerell <[email hidden]> Distortion Field!

"Art M" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I just completed an uphill time trial approx. 8% grade for 7 miles on a 26.5
lb bike. Does anyone have a formula that would tell me how much my time
would have improved on a competitive bike (resulting in a ~5% reduction in
overall weight)?

On hills such as you have described, speed is very directly
proportional to the power-to-weight ratio, although this is probably
less so for a high level pro who can maintain a higher speed (~14-15
mph) on such terrain so that aerodynamics actually do come into play a
bit more.

Last fall I had the opportunity to do an informal comparison on one of
the local passes. One day I was riding my road bike, a couple of days
later I was riding my mountain bike carrying quite a bit more gear
(cameras and such things, I estimated the heavier bike and gear
probably added 16 lbs to the total weight going up the hill). On both
rides I was wearing a recording heart rate monitor and each climb was
ridden at essentially the same heart rate.

What was suprising was that the time on the heavy bike with knobby
tires was much closer to the time on the road bike than I would have
guessed it would be using a seat-of-the-pants estimate. However when I
actually did some calculations, the time difference was very close to
what would be expected based upon the weight difference alone.

There's no question that weight makes a difference in the hills, but
it's also interesting to see just how little that difference actually
is in the real world. Or in other words, pounds probably matter,
grams probably don't.

DR