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-   -   Bike weight impact on speed and commute time (http://www.bikeforums.net/commuting/920030-bike-weight-impact-speed-commute-time.html)

mstraus 10-29-13 02:37 PM

Bike weight impact on speed and commute time
 
I have been commuting on a aluminum roadbike that is reasonably light compared to most commuter bikes (about 20 lbs before I put my lights, saddlebag, etc on). I am planning to get a new commuter that is steel (I have to ride some rough roads/paths) and quite a bit heavier, likely 30 lbs or more by the time I put on a rack, etc.

I am wondering how much I can expect the heavier bike to slow me down and add time to my commute.

For reference, I ride a bit over 16 miles and climb ~450 feet each way, somewhat steep for some sections though most the miles are pretty flat. A few sections have a lot of lights so stop and start often.

I assume a heavier bike will have the most impact on climbing and accelerating, but not clear how much that 10-15 lbs will impact my speed and overall commute time when I factor that I weigh a lot more then the bike. I realize there are probably other factors as well, such as different gearing, etc.

Since it seems like a number of people on this forum commute on different bikes, I thought some of you may have some good insight on this.

acidfast7 10-29-13 02:38 PM

how much do you weigh?

mstraus 10-29-13 02:46 PM

Quote:

Originally Posted by acidfast7 (Post 16202320)
how much do you weigh?

175 - plus I have a bag with clothes and some other stuff, so maybe another 10 lbs of gear (currently a backpack but might try panniers on the new bike)

KenshiBiker 10-29-13 02:56 PM

Quote:

Originally Posted by mstraus (Post 16202311)
I have been commuting on a aluminum roadbike that is reasonably light compared to most commuter bikes (about 20 lbs before I put my lights, saddlebag, etc on). I am planning to get a new commuter that is steel (I have to ride some rough roads/paths) and quite a bit heavier, likely 30 lbs or more by the time I put on a rack, etc.

I am wondering how much I can expect the heavier bike to slow me down and add time to my commute.

For reference, I ride a bit over 16 miles and climb ~450 feet each way, somewhat steep for some sections though most the miles are pretty flat. A few sections have a lot of lights so stop and start often.

I assume a heavier bike will have the most impact on climbing and accelerating, but not clear how much that 10-15 lbs will impact my speed and overall commute time when I factor that I weigh a lot more then the bike. I realize there are probably other factors as well, such as different gearing, etc.

Since it seems like a number of people on this forum commute on different bikes, I thought some of you may have some good insight on this.

My commute is 13 to 15 miles each way with about 250 ft of climbing (IIRC), depending on which route I take. My normal commute is on a steel fixed gear that weighs . . . well, actually I don't know what it weighs. For arguments' sake, let's call it 20 pounds. I do know my trunk bag weighs about 10 pounds on my way home (carrying tools, spare tubes, tights, jacket, base layer, long finger gloves, empty lunch boxes, etc.); probably the same on the way in (wearing the clothes, but on the way in the lunch boxes are full :)). Add a couple of pounds for lights, rack, CO2 inflator, mini pump, etc. All told I'm carrying at least 10 pounds more on my commute than on recreational rides on weekends.

So how does the extra weight affect my commute time? Almost negligibly. Yeah I might be a minute or two faster if I didn't have the rack and trunk bag on the bike. A bigger factor in my commute time is the ambient temperature and whether I've gotten a good night's sleep the night before (in either case it takes me a couple of slow miles to warm up, which really slows down my commute time). I find a bigger detriment to a "fast" commute is the way the rack and trunk bag affect the handling. I tend to not "attack" the curves as much as I normally would since the weight, positioned up high, tends to make the bike handle "like a pig" (no offense to pigs). Oh, and traffic lights really can mess up my time.

Of course, I'm old and slow, so YMMV.

acidfast7 10-29-13 03:12 PM

so it's (175+20+10)# vs (175+30+10)# ...

so i'd say roughly the time spent climbing/accelerating x 0.05 or so.

maybe 2min for every hour or so spent riding.

alan s 10-29-13 03:36 PM

Could be faster, depending on the terrain. I'm able to take shortcuts that road bikes wouldn't take, hop off curbs and ride faster on rough unpaved trails. Traffic lights tend to even things out. Not likely you'll notice much of a difference.

ThermionicScott 10-29-13 04:30 PM

Just keep the engine in shape and you'll be fine.

mstraus 10-29-13 04:45 PM

Quote:

Originally Posted by ThermionicScott (Post 16202659)
Just keep the engine in shape and you'll be fine.

Trying to get the engine in shape still. I figure riding the heavier bike will be a good trainer too, and make me even faster on the lighter bike.

If I am really only talking about a few minutes it will be worth the easier ride and option to get my bag off my back.

cplager 10-29-13 04:59 PM

There's something terribly wrong with this thread. A reasonable question was asked about weight, and the OP got nothing but reasonable answers.

What's this world coming to? :D

mstraus 10-29-13 05:06 PM

Quote:

Originally Posted by cplager (Post 16202741)
There's something terribly wrong with this thread. A reasonable question was asked about weight, and the OP got nothing but reasonable answers.

What's this world coming to? :D

And thanks to you I got a good laugh too!

Greg M 10-29-13 05:16 PM

So over the past few months Ive gone from a rack trunk
to panniers and added fenders and since I work outside
with the cooler weather I need to bring more clothing.
My rig fully loaded comes in at 45 lbs. Commute is 24 miles
roundtrip, though relatively flat, only 85 ft
of climbing, there are at least 20 lights. On
a good morning at 5:30 I can figure on hitting
7 red. The extra weight and windage took its toll
at first but after a while my average speed increased.
Remember the great lemond said it doesn't get easier you
just get faster.
And on the weekend when I get out on my klein I can
dance like lance.
No lance comments please. He was a great inspiration
when I got my cancer diagnosis.

FBinNY 10-29-13 05:36 PM

Quote:

Originally Posted by mstraus (Post 16202311)
.... light compared to most commuter bikes (about 20 lbs before I put my lights, saddlebag, etc on). I am planning to get a new commuter that is steel (I have to ride some rough roads/paths) and quite a bit heavier, likely 30 lbs [after] or more by the time I put on a rack, etc. .


How do you expect a meaningful answer when asking about comparing apples to oranges? If your junk weighs 10#s the bikes are identical in weight.

In any case weight is almost meaningless on flat rides, but can become very noticeable in hilly terrain.

You can answer your on question by buying a sack of potatoes which weighs the difference, and taking it to work and back.

mstraus 10-29-13 06:04 PM

Quote:

Originally Posted by FBinNY (Post 16202849)
How do you expect a meaningful answer when asking about comparing apples to oranges? If your junk weighs 10#s the bikes are identical in weight.

In any case weight is almost meaningless on flat rides, but can become very noticeable in hilly terrain.

You can answer your on question by buying a sack of potatoes which weighs the difference, and taking it to work and back.

The "junk" that I said is 10 lbs will essentially be on me on both bikes, currently in a backpack (probably acutally less then 10 lbs). Since this has always been there and in a packpack I would add this to my weight, not the bike. So my question was if my bike is 10 or 15 lbs heavier, how much will I notice that? Not sure I would be comfortably trying to put another 10-15 lbs on my back to test this, and even if I did I think the weight on my back would impact me differently then that weight as part of the bike (limit mobility, fatigue, etc).

Since so many cyclists are always trying to get lighter bikes, I figured there must be some reasonable estimates as to what the difference would be for lighter vs heavier bikes if everything else was the same.

mstraus 10-29-13 06:07 PM

Quote:

Originally Posted by Greg M (Post 16202788)
So over the past few months Ive gone from a rack trunk
to panniers and added fenders and since I work outside
with the cooler weather I need to bring more clothing.
My rig fully loaded comes in at 45 lbs. Commute is 24 miles
roundtrip, though relatively flat, only 85 ft
of climbing, there are at least 20 lights. On
a good morning at 5:30 I can figure on hitting
7 red. The extra weight and windage took its toll
at first but after a while my average speed increased.
Remember the great lemond said it doesn't get easier you
just get faster.
And on the weekend when I get out on my klein I can
dance like lance.
No lance comments please. He was a great inspiration
when I got my cancer diagnosis.

Any idea how much the weight increased with the fenders, pannier, and extra gear?

banerjek 10-29-13 06:14 PM

Nominally, the difference would probably be a little more than a minute and almost certainly less than two. But since you'l probably ride harder, the difference would be less. If you were switching to a lighter bike, you'd want to justify your purchase so the difference would be greater.

rsacilotto 10-29-13 06:38 PM

I've got a nearly identical commute (mileage, climbing), and I have two bikes (data from Garmin recorded in SportTracks):

1) 1988 Schwinn Voyageur, added rear rack, fenders, usually (but not always) 6lb. laptop in a trunk bag and two panniers with food, jacket, tubes, etc... probably in the 40 lb range. Morning ride is lighter traffic, net 100' uphill, ranging from 1:06 to 1:17, average across all rides is 13.0mph Afternoon ride is sometimes a little longer (range 16 to 17 mi.) and net 100' downhill , ranging from 1:02 to 1:19, aggregate average is 13.4

2) road bike (either 2000 Fuji Team aluminum 18lbs bare or 1983 Trek 760 steel 21lbs bare), carrying nothing to a light backpack (3-5 lbs). Morning is 1:00 to 1:10 (14.4mph avg). Afternoon is about the same.

I'm usually between 235 and 245 lbs.

seems like the biggest factor is hills, the road bike option doesn't have the mph dip on the morning (net climb).

chriskmurray 10-29-13 06:55 PM

Bike weight does not make much of a difference in ride time at all for me over my 4 mile each way commute, even when going from my nice road bike to my cargo bike with knobbies, it is just a few minute difference if that. For reference my road bike is around 20lbs and the cargo bike is usually pushing 45lbs.

Leisesturm 10-29-13 06:57 PM

I have a steel road-racer with fancy grade of 28.6mm Reynolds tubing from the early 80's and a steel touring machine with an average grade of oversize 31.8mm tubing from the early 2000's. The touring machine was commuterized by a previous owner and came to me already equipped with riser flatbars and fenders to which I added a rack and kickstand. The road-racer was the faster bike by about 5 minutes over 10 miles... ... until I changed the flatbars on the commuter to the same bars that are on the road-racer! Even with a loaded rack-trunk and street-clothes I am about as fast on the commuter as I am in tights and jersey on the road-racer. I still feel faster on the RR, however. Go figure, and also very much FWIW.

H

e0richt 10-29-13 07:17 PM

I saw a youtube video that compared a 1950's racer bike with a current state of the art racer. they tried to make the conditions similar as possible by using the same rider on different days even. it seems that the difference in terms of time was around 2 minutes for a ~ 20 mile ride...

Bent Bill 10-29-13 08:07 PM

2 Attachment(s)
The black bike weighs 45 lb's with the bar bag and fenders I have on it now
the red bike weighs 17 lb's
on average over the same route I am 1 m.p.h. faster on the red bike verses the black tank
hills can make a big difference
but there are not any hills on my commute to work to speak of

Darth Lefty 10-29-13 08:15 PM

I am certain I read somewhere about an old study that implied -1 mph per +10 lb (total, obviously) but if that were true I'd be going 0 mph

tsl 10-29-13 08:36 PM

Quote:

Originally Posted by mstraus (Post 16202311)
I have been commuting on a aluminum roadbike that is reasonably light compared to most commuter bikes (about 20 lbs before I put my lights, saddlebag, etc on). I am planning to get a new commuter that is steel (I have to ride some rough roads/paths) and quite a bit heavier, likely 30 lbs or more by the time I put on a rack, etc.

There's a similar weight difference between my Ti roadie and my aluminum commuters. It's just that my bikes are all about 4 pounds less than yours.

On the Ti roadie, I can do my flat long loop commute, 16.5 miles, in 58 minutes on average.

With my commuters--full fenders, 28 mm tires, dynamo front hub, rear rack, loaded panniers--I do the same route in about 1:03, or five minutes longer.

Either way, in conversation I can say "about an hour" and be within a conversationally acceptable margin of error.

That's ride time as measured by the cyclometer, not clock time which would include stoplights and such.

WestPablo 10-29-13 09:02 PM

Quote:

Originally Posted by acidfast7 (Post 16202320)
how much do you weigh?

+1

There's usually only a couple pounds difference between Al and steel bikes. Some types of steel actually weigh less than Al bikes.

Unless you're racing, bike weight shouldn't be a major factor. That especially goes for urban commutes.

A better question would be, "How much does gaining a few pounds affect my commute time?" :D

caloso 10-29-13 09:09 PM

Quote:

Originally Posted by alan s (Post 16202476)
Could be faster, depending on the terrain. I'm able to take shortcuts that road bikes wouldn't take, hop off curbs and ride faster on rough unpaved trails. Traffic lights tend to even things out. Not likely you'll notice much of a difference.

Whether I ride my 18lb race bike or my 35lb beater, it takes me 19-22 minutes to ride my 4 mile commute. It all depends on the lights.

FBinNY 10-29-13 09:12 PM

IME, weight differences are almost all about hills. I do some (lightly) loaded touring, and utility riding besides commuting and sport riding. I've come to the conclusion that every 15 pounds or so is one gear step down on the same hills, so a loss of about 10% or so climbing speed. Otherwise on level ground, once the bike is rolling I couldn't care even if I was hauling 60 pounds.

One added caveat, if you commute in a built up area, with lots of stop and go, or speed changes, then the weight penalty is that much higher because you're working harder to come back to speed after every stop.

I wasn't being facetious earlier when I suggested hauling potatoes. The easiest and most reliable way to know how weight will affect your time is to add the weight and see what happens.


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