It's my understanding that road bikes are faster than folding bikes because they are lighter, geared for more top end speed, and allow the rider to take a more aerodynamic stance.

For those of you who've used both types of bikes, do those advantages actually make a difference in denser areas? (where I assume most of us live)

I could be wrong but it seems to me that those benefits mainly affect the top end. I personally can't see how it would matter with the amount of car crossings to worry about. I've never used an expensive road bike though

If you are talking about a situation where there are lots of traffic lights, the answer is no - traffic lights are equalizers. But if there are no forced stops, then in general road bikes would be faster, roughly say 10% depending on which bike we are comparing to.

My experience in London, is that in start/stop traffic light hopping there's little difference between a light road bike and a folder – other than the light road bike (with muscle-bound hero) gets away faster and might beat more sets of lights. What the light road bike makes up over the heavier folder, it could lose at the next red light. The smaller wheel folder though, benefits greatly from more nimble handling in densely populated cities. And it folds into luggage.

Out in the sticks my 9 Kg road bike covers the same 10 mile round trip to the next village in about half the time it takes on my 20” folder and I'm no athlete. Larger wheels mean I'm not slowed so much by rough surfaces, and 21 gears instead of 7 mean I'm always spinning, not mashing. My 15 Kg MTB is slower than my road bike over the same trip, but faster than my 13 Kg 20” folder - it's rough-surface tolerant, and my folder isn't.

The stated aerodynamic benefits of small wheels (and frames) are much overstated for urban cycling, which often needs fat, heavy (in comparision) glass-proof tyres. By the time the bike gets to 20 mph, about 80% of the energy lost is to the cyclist's and bike's frame drag. In London (but not perhaps other cities) , it's hard to maintain 20mph for any distance, thus reducing the already small benefit.

More powerful riders leave less powerful riders standing, too. Very noticeable in towns, regardless of what people ride. Fast acceleration makes up for a lot in urban areas.You want fast, you need muscles, aerodynamics, planned diet, fast clothing, light bikes, un-lardy healthy riders with muscles in the right places, and road-tolerant wheels and frames. Pick any two.

I'm trying for health and light weight. I don't always succeed. I cycle most days on my road bike and I'm still overtaken by guys on Bromptons.

The bible of what goes faster than what is 'High-Tech Cycling'. It's here. The book makes the point that fitting aerodynamic disk wheels is of no benefit for hill climbing, and light weight is of little benefit on hill descents. The best accessories for speed are health and fitness.

Maybe some get used to the short wheel base. ? I didn't .. When I gave a folder a try the ride felt more like that of a 'child scooter.' The ride was just too wobbly. But, that's just me..
Can't imagine going fast on a bike with short diameter wheel.. My option for reducing the size of a 'real bike.' But an S and S couple on the frame so that it can be transported in smaller bike cases.

Bing! Another common misconception right there - "folding bikes have a short wheel base." Common assumption, seldom true. Folding bikes in general have very much the same wheelbase as "proper" bikes, at around 1000mm. The Brompton is longer than most at 1045mm. Only touring bikes have this sort of wheelbase.

As for the "wobbly" steering, experience has shown that you get used to this very quickly indeed, within one hour, and them forget about it.

+1.
As for handling, my folders are "quicker" or "twitchier" for sure but I got used to it quickly and actually prefer it. My big wheeled bikes actually feel sluggish in comparison... downright unwieldy in sleet and snow compared to folders. When it comes to transporting a bike I'll chose my folders over my S&S fitted big wheeler any day. To me the cost of the S&S just isn't worth the "break-down" size.

Folding bikes vary quite a lot in performance. If getting close to the speed of a road bike was a priority for you then select a folder that has fast rolling rubber, reasonable weight and a riding position that is reasonably aero while allowing you to develop power efficiently.

the secret to speed on a folder is having another rider ahead of you who you want to pass

Folders might not have a longer wheelbase, but for the same wheelbase as a bigger bike, there will be less wheel sticking out either end by a couple inches. Smaller wheels also mean less weight further out, which has all kinds of benefits in the tight confines of urban traffic. If you like "threading the needle" through traffic, a folder or mini- does better in an urban setting -- once traffic speed picks up, opens up, and the frequent stops get less frequent, a road bike might be the better tool for the job.

The mass of the smaller wheel is lower, and centrifugal forces
of rotating wheel are different.

+ lack of IGH suggests road bike rider will start out in the gear
they stopped for the red light in, which is probably too high..

+1

You can buy a BF Pocket Rocket Pro with full dura ace components (or campy, too) and it will be under 20 lbs and ride just like a light road bike. Which may or may not be the best choice for commuting, but YMMV (literally!).

^^^ +1

As long as your folder doesn't flex like a pool noodle and your handle bar/fit is such that you can get the power standing up, you'll be plenty fast in an urban environment.

In regards to the "wobbly" steering acclimation, untrue. At least for me. I've been riding my Dahon Curve SL for a few months now and I am just now getting used to its quirky handling.

I think a "true roadbike" would not be so fast in most citys, apart from maybe Copenhagen.. You need a fairy flat surface, no pot holes, no glass, curbs and so on. They work on the roads around here and more than once I`ve seen peopel carry they road bikes becouse of some small stones spread out on the tarmack. That is not fast. Some places the city senter is in such a shape that a MTB w front suspension and cushy tires is the way to go.

The best bike is the one best suited for the riding where YOU ride, and the one that is still there and easely available the next time you want to use it. Maybe becouse it was not stolen for the way it looks, maybe becouse you folded it and took it innside with you to avoid theft.

I think my dual drive Mezzo is quicker than a rigid road bike in town. I can change in to the right gear quicker and use close ratios to pull away at lights/junctions from other cyclists. Not really a folder advantage just IHG with an added fine range and Ultergra shifters. If the other rider gets out of the saddle it may be closer.

I commute on a Dahon Speed P8 and on a KHS fixed gear road bike... round trip 50 miles. Time on the fixie is about 1:30 each way.. Time on the folder is about 1:37 each way. I say about because there is always a variable in making or missing the lights. It is a little slower, but the handling is fine (I can ride it no hands). The folder has the adde3d advantage that it can be taken on public transportation during rush hour.

Side note-- I found a crack in the frame of the folder It is in the shop[ getting checked out. I am hoping it is only the clear coat and paint that is cracked, but I am worried...

To answer the original question, though, when I use my road bike, I can go about 5-10 minutes below the time of the fixie over the same terrain (mostly bike path, with minor streets and a few blocks of downtown traffic (in DC).

train safe-

Do you have a photo of the crack? Which part of the frame was it?

it is actually right in front of the seat tube, and there is another one in front of the hinge. I don't have a photo--and the bike is in the shop until Thursday... it is a longish crack-- about 4 inches (each one). Not sure if it is the paint or if it goes through. Will post pics when I get it back.

Continuing along vik and alhedges' train of thought ... Some of the city streets around here have lights timed at about 17mph. I couldn't keep up on my olde SS folder but it was geared kinda low and weighed 30 lbs. I've been on a couple of Bike Fridays that I could easily pace the lights with, though.

What year is your Speed P8? Good luck, I hope it's superficial, like you suggested.

i commute 75-80% on a road bike & the remainder on my beater Dahon, back & forth through the Silicon Valley. Overall time & difference between bike types very similar to buelito's... only 12-15% in practice (and mostly due to a long straight stretch near the Dunbarton bridge). Good luck in most city riding having a long enough stoplight-free span to enjoy that roadbike advantage over 20mph....

Add a rocket engine..

2009

Yeah that's about the size difs between my fast and slow folders as well - somewhere close to 10%.

Off topic, but I think you have the wrong idea about Copenhagen. It is a cyclists paradise, but that has the downside that a lot of people cycle. The cycle lanes are usually crowded, so the speed you travel at is the speed of the slowest cyclist: say 10mph.