veggie_lover

I am curious what the time differences are between the two bikes on your commute? Is the folder faster because of better acceleration?

Lalato

I don't commute on both... but I can say this. It will largely depend on distance traveled and the number of stops. If you have a five mile commute with lots of stops, a bike that quickly accelerates might win out. If, however, you have a five mile commute without stops, the bike with a higher top speed might win out.

That said... speed is largely defined by the rider... not the bike.
--sam

snafu21

There's a train of though that says smaller wheel bikes accelerate faster and are more nimble through traffic. My 20" bikes are certainly handier in town than my 26" wheeled bike.

Another piece of cycling metaphysics: bikes with suspension absorb the power a rider makes, but may sometimes be quicker on rough urban roads as the rider doesn't slow down so much...

And another: narrower handlebars, smaller wheels and a shorter wheelbase let you squeeze through gaps in traffic...

At the other end of the scale, urban bike shops are selling no end of 'hybrids' - light hardtail rigid fork bike frames with 700mm wheels. I had a Ridgeback Genesis which was about the fastest thing I've ridden through town. No idea why. Probably because it didn't weigh anything..

Light = quicker.

nigelme

I also think confidence in your bike makes a difference to your overall speed. I know I am generally faster on my Moulton, partly because I feel safer at higher speeds on it; also it can break better than my other bikes.

mulleady

How many bikes have you got Nigel lol?

You must be the UK's main rival to Jur lol!

nigelme

Only four. Have you seen the pictures of Sammyboy's shed. It looks like he lives in Evans ( Evans being a popular Bicycle Shop, not a Welshman )

Although I do also want a Downtube Mini...oh and Mezzo, and a Dahon MU XXV and a.....oops, that's a different thread.

msincredible

I have a lot of traffic lights on my commute (25 miles one-way). On the road bike it is just under 2 hours, on the Birdy it is a bit longer, 2 hours and 10-15 minutes.

vik 

I've commuted on both...I'm pretty sure I'd be faster under almost all conditions on the road bike, but in many cases the difference would be negligible...say 10% or less. This assumes you ride both on the same route...the folder may give you other multi-modal transit options that could totally change the equation.

Looking at it another way...I wouldn't hesitate to ride the folder rather than a road bike for a commute as the versatility of the folder for taking into buildings, getting on transit or getting a lift in someone's vehicle make up for any performance gap.

This of course assumes the folder fits me well and I am comfortable on it for the req'd length of my commute.

veggie_lover

Thanks, I guess that settles it.

babo

I will never complain about the one traffic light on my 2.5 kilometre commute (one way) again.

I switched to a folder with 20" wheels this year from a mountain bicycle with 26" street tires with comparable inch gears that I normally and comfortably road in. I find it far easier to get up to speed and maintain my speed on my micro-commute with my folder than I did with my mountain bicycle. My comfortable cruising speeds were around 20 kph, now they are around 25 kph and the commuting time well below the 10 minutes of what it used to be.

Sixty Fiver

I commute on my folder (it's a fixed gear) a good deal and don't find that it slows me down to any appreciable degree... the bike is fast and handles rough roads better than my road bike (also fixed) so I probably pick up a little time with that and because the bike is geared lower and spins up faster.

cooker

The small wheels of a folder accelerate slightly faster than a road bike, and if you have to use the brakes a lot, wasting the energy you put into getting your wheels spinning, that might offer a tiny advantage. However if there isn't a lot of braking the advantage is negligible. Often folding bikes have a more upright position than road bikes, and thus are less aerodynamic, which would more than offset the wheel effect.

msincredible

Keep in mind my Birdy has big fat tires...with skinnier ones, it would probably be faster.

Sixty Fiver

They (the fixed gear bikes) run similar gearings...

Fast...



Faster...



Fastest...

mroli

I do about 9 miles through London traffic each way and use the following bikes:

1) Dahon MuSL
2) Dahon Hammerhead
3) Old Raleigh single speed racer.

The Hammerhead is the fastest (around 30min), followed by the MuSL (34 minutes), followed by the single speed (37 minutes). But by the time I have bagged up the Hammerhead (taken off the headset and pedals and fitted it into the bag), I may as well have taken the MU. The single speed is there for when I go places where I need to leave the bike - it is a road bike with decent tyres on it, but just not as manouverable or quick (acceleration) as the Dahons, but it teaches a different type of cycling - momentum is all!

veggie_lover

Which model Birdy and road bike do you have?

msincredible

Birdy Yellow and Orbea Onix.

veggie_lover

Impressive looking bikes. The wheels look fairly similar in both, I would guess the suspension in the Birdy is slowing you down more than the tires?

msincredible

Thanks! I think it is the angle of my picture, the Birdy definitely has much fatter tires.

But you are right that the suspension has a very significant effect too.

pm124

I agree with this balanced view of bikes in general. I find that my Birdy is faster than a road bike, but I rarely ride road bikes (when I do, they belong to friends). The ride quality is definitely different. My old unsuspended Mu SL rode like crap relative to my friend's carbon road bike. I think my suspended Birdy rides better, but the roads here are crappy.

pm124

On a road bike, I average about 18-19MPH (though few samples). On my Birdy (equipped with a flat prone Stelvio on the front and a Brompton Green on the back of my 349 rims), I average about 20MPH (many samples, with an ever fluctuating mean over various seasons). But the conditions in NYC are more favorable for the Birdy. We have a long stretch of bike path. But once you get off of it, roadies have to stand and use their bodies as shock absorbers. It's here that I usually say parting words and ride off ahead.

Probably, all in all, both are roughly as fast. But it is highly dependent on the conditions.

Also, I should add that the Birdy with regular Marathons on it (not Racers) averaged about 17MPH when I was unloaded and on great roads in Thailand. That is a *huge* difference, and makes me think that small wheels might exaggerate rolling resistance differences between tires.

And one final point, if I wasn't into ego gratification and settled in to the 17MPH Marathons, I would probably have a faster average time to work; I get at least one flat per 10 days, and take 15 minutes to repair it.

pm124

Probably just as importantly, you are likely to be more upright on the comfort stem, no? I wonder how things might change with Selvios and a sport stem.

makeinu

To accelerate the bike to a certain speed the wheel size itself doesn't matter because even though smaller wheels have a lower moment of inertia they also have to be spun faster (and, in fact, we've looked at the equations here before and it turns out to be an exact wash).

Therefore, smaller wheels will only offer better acceleration if they are lighter. Now, although it might be argued that the lowest possible physical limit on weight should be lower for smaller wheels, folding bike wheels are almost always built closer to the relative design proportions of BMX wheels (in terms of the relative spoke angles, relative spoke hole placement, relative hub widths, relative flange heights, etc) than road bike wheels and even when the designs are more optmized for speed they still usually suffer due to the economic infeasibility of tooling up with the same state of the art manufacturing technology used to build the (more popular) larger wheel sizes. So in the end it seems that, more often than not, folders have worse acceleration not better.

Skeleton

I commute everyday on any of my four bikes. The commute covers 10 kms from my suburban house to my downtown office in Vancouver. Below are the one-way travel times averaged for each bike.

1) Cervelo R3 - road/racing bike
- Sunny summer conditions
- 18 mins

2) Dahon Cadenza
- Summer rainy conditions
- 20 mins

3) Dahon Speed TR
- Occasional
- 22 mins

4) Norco Commuter (heavy)
- Winter rainy conditions
- 24 mins

So, why is the racing bike only marginally quicker in time than the Dahon Cadenza? Well, cuz speed on a commute is only significant during the acceleration phase of the stage. On an urban commute, about 20% of my time is accelerating; it is in this stage that my Cervelo is WAY quicker, but in doing the math, it only can reduce my commute time by 10%.

So, my point is any good road bike will be sufficiently fast overall in an urban commute.

bhkyte

All my "fixed bikes" are slower than my main folder !