sam_cyclist

I recently test rode a 2014 Giant Defy 2 and 2015 Giant Defy 1. The shop weighed both bikes at my request and the Defy 1 weighed more than a pound less. It's also about $500 more expensive.

I did a bit of climbing and obviously, I didn't notice any difference in my ability to climb with either bike.

I'm wondering if getting a bike "significantly" lighter, say 3 or 4 pounds lighter or more, would make a noticeable difference either in overall handling characteristics and especially in how quickly I can climb hills.

This is a bit of a hypothetical question as I don't plan on spending several thousands of dollars on a road bike, but I'm wondering how much of a performance advantage I would gain from a bike which is 3+ pounds lighter than the Giant Defy 2 I test rode.

Drew Eckhardt 

The impact proportional to total weight.

For example, together my bike and I weigh 165 pounds so loosing a pound of bike weight would increase my speed up the steepest hills 165/164 = 0.6% which is 22 seconds for each hour of climbing I do.

4 pounds would be a full 2.4% faster and knock nearly a minute and a half off an hour climb.

On flat ground the results aren't significant (rolling resistance is constant and power to overcome it linear so most of your power goes into overcoming aerodynamic drag proportional to the square of velocity with power to overcome its cube) and not enough energy goes into acceleration for that to matter.

Mostly it'll look nicer and be more pleasant to hoist onto your repair stand unless you race, are in the mountains, and have a build conducive to climbing (about 2 pounds per inch is a good target).

Marin

Bicycle Speed (Velocity) And Power Calculator

This is a pretty accurate calculator. You'll be suprised how much difference aerodynamics make even on 8% climbs, going from the tops to the drops is similar to losing 1kg of weight...

Stucky

I've always felt that while lighter bikes really don't do anything for you [Within reason.....I mean, you don't want to ride a 35 lb. tank....], lighter bikes do seem like they just "feel" better than heavier bikes- but I question how much of that better feel is due to the relatively small weight difference, vs. the fact that heavier bikes often have more "relaxed" geometry, and slower handling? [Which is probably what accounts for their less-nimble feeling, as opposed to a few pounds.]

My first road bike weighed 24 lbs., I now have a 17 lb. bike. Very little difference in my performance, unless you count seconds- which I don't. I like the "feel" of the 17 lb. bike much more- but I think that's because it is an aggressive-geometry race bike vs. the heavier bike, which was a relaxed geo. Comparing the 17 lb. newish CF bike to my 19 lb. old AL bike, I actually prefer the latter...and notice no difference at all as far as the weight. If I were blindfolded, I wouldn't be able to tell which was the heavier one.

I've heard it said that 12 lbs. off the bike/ider = 1 MPH. It sounds about right to me.

RChung

I haven't found that particular calculator to be accurate at all, and I compared it with a calibrated on-bike power meter.

Doge

I think this applies to the mid-tier and lower, not the high end bikes that all have the op en groups.

I would bet if you took two stock bikes and added lead weights to the lighter to make them equal (which is done for UCI weight requirements) the originally lighter bike would be faster and ride better.
The lighter stock bikes tend to have more refined components that remove weight where it is less needed.

Its your money, but I'd generally go lighter weight as it is often better stuff.

rms13

According to Strava, my rides on my 17lb carbon bike and my 21lb steel bike are pretty similar. My avg speed on the same rides is always around the same regardless of bike. And yesterday I did I ride that I have been doing 2-3 times a week for 3 years and I still managed to hit some PRs riding the heavy steel bike.

The characteristics of the two bikes are very different and weight isn't the most important factor. But with that said...$500 to loose 1 lb sounds like a decent upgrade.

wphamilton

I'd take that bet , as long as the added weight kept the same general balance.

I'd also be willing to bet that you could add say 200 grams on each of the derailleurs, then move them to the seat tube and stays, and you would see no difference is speed or handling.

Doge

Well the guys that have to make UCI weight (us this year) care a lot about where the weight is. And they say they can feel the difference. The Shimano Di2 battery moved from seat post to BB matters. Bolted on lead goes at the BB shell, or now popular screwed under the BB.

I know my 500g Brooks pro saddle was very noticeable over a lighter one. The pendulum effect can be felt.

wphamilton

"as long as the added weight kept the same general balance." moving that much weight from seat post to bottom bracket changes the balance quite a bit.

My suggestion, following your premise about component weight, does not change the balance.

Also, just to be clear, I don't doubt at all that a heavier saddle is "noticeable" to you. I do doubt that the extra weight on the saddle as opposed to the frame makes a difference in speed, or in handling.

Doge

Where the weight is (Moment of Inertia) makes a difference in handling. Typically not felt sitting, but felt standing.
Moving the same weights apart evenly maintaining balance is changing the moment and the handling.

Components/groups do not remove weight equally from all parts. A $500 more expensive bike with the same groupo (this thread) will often lighten the seat and post and bars and stem. If you are lucky the wheels and tires. That is weight that can be felt - even if you re-add that same weight to the middle of the frame.

My advice was go with the extra $500 bike assuming that $500 went into better parts.

Doge

On weight location. Last night we changed cleat hardware from steel to Ti. That saved 17g/pair at the shoe. My son cannot feel that. But he can feel the 100g difference in mass at the pedals. If the cyclist is the type to stand, move the bike from side to side, accelerate then this little stuff all adds up. If they sit and steady state ride - then I doubt they would feel it, but generally the higher end stuff is better made.
The picture on the left besides being lighter they are better finished.

Seattle Forrest

I carry my bike up three flights of stairs at the end of every ride. But I'm moving this month.

wphamilton

You were fine until the bolded part. It could doubtless be "felt" by someone spending enough hours on the bike, but any significant difference in handling is dubious for the change in moment we're considering. Put some actual numbers to it, and you'll see what I mean.

I don't know if you noticed, but I was careful to avoid suggesting the brake calipers in my example. 200 extra grams on the front brakes might affect handling to a perceptible degree. Although I doubt it, but it could be debatable so I avoided suggesting it.

Moving 200 grams from the derailleur to the adjacent spot on the frame on the other hand, as I suggested as a test of your thesis and which I note that you avoided twice , will change neither the balance nor the moment of inertia. You won't see any difference in speed or handling.


The three pounds could be "felt" but result in little or no performance advantage for OP, other than the brute force uphill ding of 3 pounds.

Putting the $500 into a wheelset and tires would in all probability lead to more performance benefit than $500 in seat, seat post, bar and stem. Or lighter drive train components.

Doge

I avoided dealing with moving weight from derailleur to frame because I agree. Apparently we both understand the effects of mass and its location.

My "thesis" was that generally more expensive components are better - and you generally get value for $500 - in that mid-range. I buy lots of stuff that is more expensive, lighter and "not better", but I am not like the OP. In the mid-range Ultegra and the parts that come with it are better than 105 and parts that come with it - that's all.

The 2nd point was depending on riding style/type - a rider may feel this difference. A 10,000mile/year rider would more times than not be able to tell you which bike was the $500 more costly.

I have put numbers to this stuff in the past (general physics in the 80s when I commuted to school by bike) and it is hard. I find tests matter more than calculations because no calculation I read account for the side to side movements and those vary a whole bunch rider to rider. I support my kid who is a 10K mile/year guy and I know he notices this stuff. Our recent and ongoing test - wheel weight and aero (see 33 Tech forum).

Carbonfiberboy 

That's interesting. Is there an online calculator you like better?

bruce19

How Lightweight Do You NEED Your Bike To Be?

Doge

Calculators give general ideas. I think this is close. But even 4 runs in a row with wind about the same on the last two and same power - we get differences.
The calculator was pretty close on a recent test, but the grade is off a bit.

RChung

Analyticcycling.com, but you need to know your inputs so it's less friendly. I don't like to speak ill of the dead but the issue with Kreuzotter's calculator is that it just assumes standard values for Crr and CdA and I've found that they vary quite a lot between individuals and even for a single individual. That's for a single bike type -- the values it gives for different bike types is similarly inflexible (and the values it gives for recumbents are especially optimistic).

Dave Mayer

I commute on a road bike. It is lots of hills and starts and stops. Weight does matter. Last week I was riding on a 16 pound carbon bike. This week a steel bike at 21 pounds, with similar controls (brifters).

The light bike sure feels faster up the hills, and during accelerations. Then I installed some lightweight tubular wheels on the steel bike. A revelation. Night and day. Now the steel bike feels 'faster' than the carbon bike. Reducing weight on the wheels has advantages far beyond anywhere else on the bike. And that tubular wheels offer savings in rotating inertia well beyond anything than is possible with clinchers.

wphamilton

I don't argue with that - I take issue with what you originally wrote: "the originally lighter bike (with added weights - ed) would be faster and ride better. The lighter stock bikes tend to have more refined components that remove weight where it is less needed. "

That's saying that the lighter bike, because of the higher quality group set etc, would be faster and ride better. This is a fairly provocative statement, and a dubious one in my opinion. These higher quality components will not make your bike faster nor handle better. And riding better because of removing the weight "from where it is less needed" remains also unsupported, and in my opinion also dubious. Unless you're talking about thinning tube walls in areas less stressed, but that isn't what I call a "component".

OP asked specifically for performance gains from buying a lighter bike. In a nutshell, all he can honestly expect is the weight difference over total weight, up a steep enough hill. Roughly 1%-2%. Do you honestly believe that the slightly higher tier of components on a $500 more expensive bike will produce more performance gains for OP than, for example, $500 of quality racing tires and a better wheelset?

Let's not get into qualifications about riding or education, since I think those are meaningless in internet discussions. I ride a lot also and I know the science, which claim makes me no more nor less likely to know what I'm talking about.

xscottypx

idk about bikes but when i dropped like 700+ grams off my wheels i felt a big difference

rideBjj

Interesting. I have this to add:

Last week I swapped out the 1950g wheels I've been using on my bike for a set of DurAce C24's which are more than a pound lighter.

Since I did, the bike seems to sprint / accelerate faster. I have held off on assuming it's because of the wheels, because it could be placebo, or I've been having a more "fit" week, etc.

But a few days ago I did a ride I do every week which has 5 miles of climbing with grades up to 13%. After that is the fun part, 7 miles of awesome fun downhill.

Anyway, this last time I did the ride, the climbing felt noticeably easier. I was out of the saddle less, and when I did get out of the saddle, I was able to get a higher cadence going in the same granny gear I usually grind along in. It was still hard, but it didn't kick my ass nearly as bad as it usually does. In the past, there have been times on the steepest sections where I'd have to fight the urge to stop and rest. I'd need to remind myself "its almost over" and "think of something else" and "keep going, f**ing pu**y!" etc.

This time, I just pedaled along and while it was still an effort, it felt much more manageable. I don't usually log my times and average speeds on rides, or sections of them, but I'm pretty sure I was faster.

Supposedly, lightening your wheels has the biggest impact. This may be that, it may be placebo, it may be that i hit a new fitness peak.

Stucky

Wheels, mainly when it comes to accelerating and climbing, is where weight reduction makes the biggest difference. Rotating mass.... A one pound reduction in wheel weight probably has a more noticeable effect than losing 5 lbs. off of the rest of the bike.

Doge

That has little to do with mass and calculations. We have lots of old Campy, SRAM Red, Shimano 105, Ultegra and DA (most version versions over last 30 years).

One group uses stock ceramic pulleys, one bearing and one sleeves.
One group used bearings in the brake pivots, another does not.
One group...on and on.

In almost every case the correlation between price, weight and superior stuff is the same. The more expensive (within manufacture) is also lighter and also better refined.

Does better working stuff make you faster? Yes.