Tarmac rim brake options no more

Discuss light weight issues concerning road bikes & parts.
Mr.Gib
Posts: 3670
Joined: Fri Mar 18, 2005 4:12 pm
Location: eh?

by Mr.Gib

Bordcla wrote:
Tue Dec 17, 2019 7:13 pm
Calnago wrote:And 1lb of weight on a high end road bike is very meaningful to me.
You do realize that this is a 100% placebo/mental restriction that you impose on yourself, right? Your own weight varies by more than that over the course of a single ride. Do you ditch your saddlebag, bottles and empty your pockets before every climb?
The laws of physics tell us that extra weight is not 100% placebo (curious about your sources). The impact of extra weight on acceleration and climbing is very real and quantifiable. The magnitude of the impact and how important that impact is, can certainly be debated.

Regardless of the magnitude of the effect on performance, some people like the feel of a lighter bike. And no matter how heavy the rider is or what they may be carrying, a bike that is a pound lighter, is always a pound lighter and consequently requires less energy to accelerate or to raise its altitude.
wheelsONfire wrote: When we ride disc brakes the whole deal of braking is just like a leaving a fart. It happens and then it's over. Nothing planned and nothing to get nervous for.

robertbb
Posts: 1348
Joined: Thu Jul 23, 2009 3:35 am
Location: Melbourne, Australia

by robertbb

Mr.Gib wrote:
Tue Dec 17, 2019 7:34 pm
Bordcla wrote:
Tue Dec 17, 2019 7:13 pm
Calnago wrote:And 1lb of weight on a high end road bike is very meaningful to me.
You do realize that this is a 100% placebo/mental restriction that you impose on yourself, right? Your own weight varies by more than that over the course of a single ride. Do you ditch your saddlebag, bottles and empty your pockets before every climb?
The laws of physics tell us that extra weight is not 100% placebo (curious about your sources). The impact of extra weight on acceleration and climbing is very real and quantifiable. The magnitude of the impact and how important that impact is, can certainly be debated.

Regardless of the magnitude of the effect on performance, some people like the feel of a lighter bike. And no matter how heavy the rider is or what they may be carrying, a bike that is a pound lighter, is always a pound lighter and consequently requires less energy to accelerate or to raise its altitude.
I don't disagree with you on this, but you have to put it in context.

Losing 500g off the weight of a bike may seem like a lot when compared with the weight of the bike. 500g off a 7kg bike is an "improvement" of 7.14%.

Losing 500g off the full system weight (all of which has to fight gravity and go uphill, and which therefore must include the rider) is a loss of 0.71% if you factor in a 63kg rider. It's even less if the rider is heavier.

by Weenie


rollinslow
Posts: 232
Joined: Fri Dec 21, 2018 2:25 am

by rollinslow

I think there is something to be said about the way a light bike responds when you put some power down onto it. It will take less to accelerate a light and stiff object than a heavier one. That's what's I've always loved the most.

That stand up in the saddle on a hairpin to put down max watts and get the bike over it. I definitely notice the weight there.

AJS914
Posts: 3875
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I plugged into analytical cycling how much time I'd save on a local climb (takes about 18 minutes) if I lost 10 pounds. Sadly I'd only save around 10 seconds.

spdntrxi
Posts: 3545
Joined: Sat Jul 20, 2013 6:11 pm

by spdntrxi

AJS914 wrote:
Wed Dec 18, 2019 12:56 am
I plugged into analytical cycling how much time I'd save on a local climb (takes about 18 minutes) if I lost 10 pounds. Sadly I'd only save around 10 seconds.
which is why I went ahead and got a aerobike and a donut.

5DII
Posts: 224
Joined: Sat Aug 09, 2014 7:52 pm

by 5DII

Calnago wrote:
Fri Jul 05, 2019 6:15 pm
syplam wrote:how about braking when its wet ? I always thought disk brakes are better when it's raining? Please prove me wrong before I get a disk bike.
That’s an interesting one, because by most if not all accounts discs are better in the pouring rain, but I have to admit I’ve never ridden discs in a really bad rain storm, although I live in a very wet climate. My dedicated rain bike... full fenders and Nemesis rims works fine and I exercise caution in those conditions regardless. The roads are still slippery despite what you brake with.
Im looking at building a winter bike and was wondering how you decided on using nemesis rims for winter riding?

mscullion
Posts: 6
Joined: Tue Jul 09, 2019 8:28 pm

by mscullion

Road bikes have had rim brakes for a hundred years so this is a major shift and much larger then D!2, areo stuff or even carbon. This has changed the whole design, maintance and care of bicycles. Most have a stock pile of parts that interchange like wheels, and componets but become useless and there is no interchangeabilty. I think the big deal with disk brakes is it changes the frame structure and compatability. No other component changes the entire structure of a bicycle like disks do.

I just built a disk bike frameset and the cost was extraordinary for the the Ultegra hydaluic shifters, brakes plus rotors. I also had to have the LBS install and bleed which wasnt cheap. I have rim brake bikes and a couple of disks. I didnt really care when 12 speed and/or electronic shifting came out as none of that interested me. i have had a DI2 in 10 speed which was ok but no big deal. I also dont find Disk brakes to be a big deal for my riding and pretty unnessary but cant say they dont make me feel a little more in control but i dont use brakes much anyway as its pretty flat with rolling hills where I ride.

If your just getting into cycling then disks are great and cant understand why anyone would not want them but, if you have been building an aresnal of bikes and equipment for the last 10-20 years then maybe a new disk brake bike that none of your wheels or or components (shifters, brakes, brake pads, and etc) fit on maybe more then a bumber

User avatar
Miller
Posts: 1717
Joined: Thu Sep 21, 2006 8:54 pm
Location: Reading, UK

by Miller

AJS914 wrote:
Wed Dec 18, 2019 12:56 am
I plugged into analytical cycling how much time I'd save on a local climb (takes about 18 minutes) if I lost 10 pounds. Sadly I'd only save around 10 seconds.
Are you sure that calculation is correct? 10 pounds is enough weight to make a real difference on climbs.

AJS914
Posts: 3875
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I think I did it right. It isn't a super steep climb. We ride it in a big ring usually on our group ride. I'm sure one saves a lot more time if the climb is a lot steeper.

edit - just reran it. 18 seconds.

This Much Less Weight 4.5 kg
Over This Distance 7000 meters
On Hill of Slope 0.02 Decimal
Faster by 17.89 s
Ahead by 143.86 m
Frontal Area 0.5 m^2
Coefficient Wind Drag 0.5 Dimensionless
Air Density 1.226 kg/m^3
Weight Rider & Bike 90 kg
Rolling Coefficient 0.004 Dimensionless
Power 250 watts

I'd be curious as to what an aero bike saves on the same climb.

Weaklegs
Posts: 3
Joined: Tue Dec 03, 2019 5:18 pm

by Weaklegs

AJS914 wrote:
Thu Dec 19, 2019 9:15 pm
I think I did it right. It isn't a super steep climb. We ride it in a big ring usually on our group ride. I'm sure one saves a lot more time if the climb is a lot steeper.

edit - just reran it. 18 seconds.

This Much Less Weight 4.5 kg
Over This Distance 7000 meters
On Hill of Slope 0.02 Decimal
Faster by 17.89 s
Ahead by 143.86 m
Frontal Area 0.5 m^2
Coefficient Wind Drag 0.5 Dimensionless
Air Density 1.226 kg/m^3
Weight Rider & Bike 90 kg
Rolling Coefficient 0.004 Dimensionless
Power 250 watts

I'd be curious as to what an aero bike saves on the same climb.
Do I understant correct...slope 0.02 is 2% slope? Big ring on a climb WTF. If it's correct than it's not a hill or climb, more like almoust flat, and you can ride 30km/h on 2%. Weight makes difference on over 5%slope. Everything below is for aero gains.

User avatar
silvalis
Posts: 760
Joined: Mon Sep 07, 2015 1:02 am
Location: Aus

by silvalis

is 2% classed as a false flat?
Chasse patate

TobinHatesYou
Posts: 5066
Joined: Mon Jul 24, 2017 12:02 pm

by TobinHatesYou

silvalis wrote:
Fri Dec 20, 2019 1:22 am
is 2% classed as a false flat?
1% is a false flat. 2% is sort of a transition point. It’s certainly not typically the grade used on calculations like this. I tend to start at 5-6% minimum because that is where a lighter bike would be better for me on climbs longer than 30min.

Bordcla
Posts: 250
Joined: Wed Dec 20, 2017 3:42 pm

by Bordcla

robertbb wrote:
Wed Dec 18, 2019 12:20 am
Mr.Gib wrote:
Tue Dec 17, 2019 7:34 pm
Bordcla wrote:
Tue Dec 17, 2019 7:13 pm
Calnago wrote:And 1lb of weight on a high end road bike is very meaningful to me.
You do realize that this is a 100% placebo/mental restriction that you impose on yourself, right? Your own weight varies by more than that over the course of a single ride. Do you ditch your saddlebag, bottles and empty your pockets before every climb?
The laws of physics tell us that extra weight is not 100% placebo (curious about your sources). The impact of extra weight on acceleration and climbing is very real and quantifiable. The magnitude of the impact and how important that impact is, can certainly be debated.

Regardless of the magnitude of the effect on performance, some people like the feel of a lighter bike. And no matter how heavy the rider is or what they may be carrying, a bike that is a pound lighter, is always a pound lighter and consequently requires less energy to accelerate or to raise its altitude.
I don't disagree with you on this, but you have to put it in context.

Losing 500g off the weight of a bike may seem like a lot when compared with the weight of the bike. 500g off a 7kg bike is an "improvement" of 7.14%.

Losing 500g off the full system weight (all of which has to fight gravity and go uphill, and which therefore must include the rider) is a loss of 0.71% if you factor in a 63kg rider. It's even less if the rider is heavier.
And 63 kg is a fairly light rider. That's the reported TDF race weight of Chris Froome.

I'm at less than 6% body fat, and way lean, but still 81kg. Losing 500g represents .6%.

If people truly feel that little difference when accelerating their bike out of a hairpin, they are more sensitive than I am.

I will feel the effort, the sting in the legs, the burning in the lungs, but not the less-than-a-tenth-of-a-percent less mass to displace.

Post Reply