30 lb Geared Bicycle vs 20 lb Single Speed, Which Is Faster for Commuting? This is not a literal question so I'm not looking at / for specific models, but more a theoretical one. Let's assume I could choose between two bikes for commuting, one with a modern 22 speed drivetrain setup and another with a single speed. The geared bike weighs 30 lbs, and the single speed bike weighs 20 lbs. They cost around the same (not that it makes any difference in this particular scenario). My commute would be about 8 miles each way, so 16 miles round trip, in a major U.S. city with normal traffic and not too much elevation gain (say around 150-200 ft or so, also round trip). Let's assume the city has 4 seasons and I would commute every day. Let's say I weigh around 140 lbs. I've tried to outline both the pro's and con's below, but I'd like to figure out if I'm missing something.

Geared Bike


Gears may allow for a faster overall speed if there are long uphill or downhill sections, or long open flat stretches with no traffic


Single Speed Bike


There is a weight reduction vs the geared bike (in this scenario about 6%) which may result in an increase in acceleration, especially when accelerating from frequent stops in traffic or going uphill
There is a slight increase in drivetrain efficiency due to a lack of derailleurs and a "perfect" chainline


If the rider regularly encounters traffic or does not ride over any substantial hills, I believe the single speed may actually be the better choice in most urban commuting scenarios. Given all of the following information, which one do you think would be faster and why? Any real world experiences and results would be welcome as well. Please disregard any other benefits not related to speed, such as the single speed having less parts = less maintenance and more reliability, generally more quality for the same amount of money spent on a single speed, etc.

Edit: I feel like everyone is missing the point of this question, so I thought I'd clarify. I own a modern 22 speed bike, a fixed gear, a single speed, a single speed mountain bike, and a relatively light 3 speed IGH. As I mentioned before, I do not want to hear about the pro's and con's of actually using each one for commuting in terms of cost, maintenance, etc.: I know about these already having owned them. I just want to know, given my particular scenario, which one you think would be faster and the technical reasons why you came to that decision. I'm not interested in discussing anything other than implications on commuting speed for this particular question.
To answer this question you have to factor in all the specifics of your commute. In particular those are (including yours for completeness):


Length of your commute (in time - distance is less relevant).
Steepness of ascends (and descents if you accelerate down-hill).
Overall 'windiness' of your city.
Number of full stops and slow-downs you have to do (due to corners, crossings and traffic lights).
Your physical strength and general fitness.
Amount of time you are willing and able to spend maintaining your bike.


Number (1)2-5 need to be considered when choosing your gearing. If the ascends are steep (or you have expect strong headwinds often) you'd need to run a smaller gearing. That would enable you to power through the ascends and accelerate quickly - but it would also limit your top-speed. Also your long-time endurance would be worse on a high-cadence gear-setup.

Meaning: in such conditions it would probably be better to ride a couple of gears. 200%-300% difference should suffice - a range that you cat get out of a small road-race cassette.

If in turn your commute consists of shallow ascends and descends, and you pack enough strength to decently accelerate the gear-ratio you'd want to be running during your average commuting speed - then you can do just fine on a single-speed bike. I rode a commute of 27km (~17mi) on a single-speed bike for years without trouble.

If you're still undecided you might want to consider my point 6. Maintenance can be a hassle, costing time and money. But it is not necessarily much more expensive on a geared bike. On a single-speed bike you have much higher wear on your chain ring and the sprocket, due to the higher torque you put into your drive-train. On a geared bike that wear is considerably lower, since you can down-shift to accelerate, and it is spread over a number of sprockets instead of just one.

My personal choice for commuting: Internaly geared hubs

You can combine both of those upsides by running an internally geared hub. Something like the Shimano Alfine 8 should be more than enough for all commutes, and doesn’t cost more than most other geared drive-trains. It’s insanely durable and needs very little maintenance. I rode one for approximately 25-30000 km (including a technical trans-Alps tour with 20000 vertical meters) and it’s still going strong in my daily-driver commuting MTB. Of course those upsides are bought with a little lower transmission efficiency and a  higher weight. But that shouldn’t be to bad for a commuter. Plus you get instant-shifting capabilities – even without pedaling! This is something I grew quite fond of, because it enables me to brake and shift later – makes it easier to keep the speed high.