How much slower 20" folder vs 700c?
 

So do any of you avid riders have statistics as to how much slower you are on a specific ride with your 20" folder vs your 700c bike.

With Strava (map my ride etc) it is really easy to ride the same route on different bikes and figure the difference..

https://www.xootr.com/swift-folding-bike-faqs.html

I used to pass rodies on my Xootr Swift w/NuVinci N360 hub.

for some of the riding i do--in-town, frequent acceleration/deceleration, speeds limited by traffic and the human environment--I'd reckon a 406 wheel bike is just as fast, if not faster due to the easier acceleration.

I don't claim to be a fast or strong rider but I seem consistently ~1 mph slower on a Brompton M6R w/Marathons and half clips vs my Specialized Tricross Comp w/700x32 and clipless which is ~7%. I just finished rigging a lower more aero position for my Brompton's M bars that should reduce the gap significantly (an initial run proved promising).

I've used a Garmin 60csx on fixed loops through mildly hilly terrain several times to compare.

Though I think I am quicker on my Dahons as opposed to my Hybrid Trek 7.2fx (700x35), I would sometimes be more comfortable on my full-sized Trek (I upgraded the crankset to a Tiagra 50/34). Though, I think the fastest I've recorded on Strava is on my Dahon Vybe c7a (53t FSA crankset with 14-28t 7spd gearing). I would actually be with a road bike for some time but I'd red and they'll just pass me by eventually. Regardless, I love both my Dahons and my Trek 7.2fx. I average both around 8-11mph (I'm from NY, so climbs actually slow me down a lot)

I tend to be just a little (< 1 mph) faster on my Cannondale 700c bike than on my Bike Friday (451mm). But the Bike Friday is a bit faster than my 700c Spec. Sequoia.

My 20" tired Moulton is as fast my 700c touring bike. Both have drop bars.

My Brompton feels a little slower than my Swift, especially when I load it up with 15-20 lbs of stuff compared to 3 with the Swift. My Fuji track on level ground with no headwind feels faster than the folders. My Centurion with studded 700 C Schwalbes is the slowest of the bunch. My Holdsworth with 21 to 110 gear inches is the fastest with a lot of winds or steep hills. The kind of riding, the tires and the headwind make the most difference to me. I will say that on longer rides on poor pavement the 700 cs are more comfortable but that may be due to different handlebars.

How fast the bikes go is a matter of how hard you pedal as the rider.

How efficient are the bikes is a better way to ask the question, because it gets to the issue of how much speed do you get for a given effort or power level.

To address that issue, though, is very complicated, because it involves things like rider position, tire quality, and gearing.

Generally speaking, a 20" wheeled bike is no slower than a 700c wheeled bike if they're set up the same. If both bikes put the rider in the same position, if they have tires of the same Crr, if they both deliver the same kind of stiffness and pedaling efficiency, and are geared equivalently, then apart from small variances of aero drag of the frame designs which could really begin to take a toll at very high speeds, then the speed results should be about the same.

Practically speaking, though, 20" wheeled bikes tend to be slower at spirited road riding speeds because they are under-geared and tend to put the rider in a more upright position than a racing type drop bar bike.

Be aware that "tend to be slower" means little, and someone riding, say, a Tern Verge X18, which can hang in a spirited road riding group working north of 20mph, may be way faster than someone who only leisurely rides their 700c.

In the end, though, there are very few 20" wheeled bikes built to hang with a typical road bike being ridden by a strong rider. The 20"ers are generally slower simply because it's hard to find one with the gearing to support it.

I have a 20"er with a 60t large chainring and an 11t rear, but while that's more gear inches than a typical Dahon folder, it's less than the Verge X20, and far less than your average 53/11 gear combo on a 700c.

In theory a smaller wheeled bike would be faster on a perfectly smooth surface since it accelerates faster and has less aero drag, but a 700c would be easier to maintain high speed since the wheels have more inertia.

It would be tough to make a fair comparison unless you matched things up.
Most important is the body position since that makes the most drag.
Then the wheels should be full discs running the same brand/compound of tires and set to psi levels that allow identical size contact/friction patches.
The bikes would need the same drivetrain components and stick to one identical gear ratio after a running start in an enclosed no wind space.
A power meter and cadence meter would be needed to keep those the same over a run too.

With all that said, I think a 700c suspension (2017 Domane/Roubaix) would be fastest on a long run, but a Birdy or Moulton in stop and go traffic.

I think your gearing is larger than the X20. As far as I know, the X20's largest gear is 55/11.

I have a heavily modified P18 (w/ 20 speeds)

I do a fair amount of riding with fairly decent riders on full size CF bikes w/ 700c wheels. On flats and hills I'm right there with them and often ahead of them on hills. However, on descents, I don't have a chance. It's simply impossible to keep up. They lose me every time.

I agree that it largely comes down to gearing. My largest chainring is 56 and smallest cog is 11.

Sorry, you can't keep up with the roadies on the downhills because of the gearing on your bike is too low?

There's only so big a chainring you can install on a 406er before the ring is too big for the chainstay, it leaves you with gearing too tall for the hills, or it just looks incongrously big.

An great option for wide-range gearing on a small-wheel bike is the SRAM Dual Drive hub. I've got one with a 47T single ring which, coupled with the SDD hub, is as if I were carrying a 64/47/34T triple crankset. 64/11 gives about 108GI. Couple it with a 53T and an 11-36T cogset, and you've got a 72/53/39T triple with 20-121GI. Another advantage of the SRDD is little cross-chaining on the single-ring drivetrain; instantaneous, no-clunk shifts; and ability to shift at a standstill.

Ah, I was thinking that the X20 used the Capreo hub design to fit a 9t cog.

Even if a 20"er has the same gearing as a 700c, in any given gear pedaled at the same RPM, 700c will travel a greater distance, so a 20er needs even more gear range than a 700c bike to keep up. Outside of one-off record attempt small wheelers, I've never seen a 20" with gearing to match a 700c's capability.

The high end of a roadie, sure. But that sort of gearing is only needed with high speed downhill racing. On level roads, a 20" bike with 60t ring and 11t cassette is more than adequate. My Ti Swift's highest gear is 109" while a roadie with compact crankset has just 1 extra higher 10% step for 120".

So maybe you won't keep up with a roadie on a long downhill while they are cranking massively but for all other road riding 109" is just fine.

No, if the top gear is the same (expressed in either gear-inches or in development) then the speed at a given rpm will also be the same. E.g. my Bike Friday with 451mm wheels (20" outer tire diameter) has a top gear of 109 gear-inches using a 60t ring and 11t cog while my Cannondale road bike with 700c (622mm) wheels has almost the same top gear (110 gear-inches) using a 53t ring and 13t cog. I could certainly get even higher gearing for both bikes, but the current high gear is already only useful for downhill runs or when in a fast paceline since I'm not strong enough to spin that gear on flat ground. Ultimately the highest useful gear on a bike is determined by the legs of the rider, not the size of the bicycle wheels.

Exactly which Sram hub do you have? I'd like to check it out.

So I totally understand that gear inches is the true wheel size equalizer.

My swift came with a 11-32 8 speed and a 52 big ring and 406 wheels. As I understand it that gives me a top gear of about 90 gear inches. I do not need a higher gear on flat smooth pavement with this bike as I run out of power.

I have an old road bike I have not ridden in years but I am going to pace myself on an 6 mile paved bike trail that is fairly flat. I set up a course with Strava that has no interuptions from stop lights and only 125 feet of elevation change.

I am going to setup a course going the opposite way also to try to eliminate wind issues and to get more readings.

I was hoping someone else could give true numbers in a similar test. Over the next week I plan to run the course at least a couple of times on both my old 700c and my swift. I will post my results.

When I said "same gearing," I meant as in a 53t big ring and 11t cog; that gearing (gear combo?) at the same RPM, will give a slower speed on the 20er compared to a 700c. I was trying to figure out what the OP was getting at; the "how much slower" question didn't make sense to me unless we arbitrarily and artificially restrict gearing to single speed at a fixed RPM.

I am using the SRAM Dual Drive hub (v.2) which, in addition to taking a regular cogset, provides for three drive bands. Over-drive at 1.36x, Drive at 1x, and Under-drive at 0.73x. You can think of it as a multiplier on your chainring, or a multiplier on your effective wheelsize.

https://sram-cdn-pull-zone-gsdesign....lick_web_2.jpg

The advantages? Wide gear range, plus the three advantages I listed in the earlier post. Another advantage is that the hub, clickbox and needle (the interface between the hub innards and clickbox) costs only $150.

The disadvantages? As I see them, and for my use and experience in two years, there is only one minor disadvantage, the weight. The hub alone weighs 960grams, which is about 2.5x the weight of a normal freehub. Others will say the allegedly fragile clickbox is a disadvantage. In two years of riding, and riding hard at times, the clickbox has never come off once, and it is intact with no damage at all. The clickbox, imo, is a non-issue. Still worried? Carry a spare. It costs a whole $10, weighs 90 grams, and is easily available at Amazon. Ditto for the needle; five grams, five bucks. In the event, catastrophic failure of the clickbox still leaves you with the entire range of the cogset in Under-drive (18-59GI) at your disposal. It does not mean you will be walking back.

Another disadvantage is that v.3 of the hub comes only in 36H, and that is overkill for 20" wheels. Good thing I have the v.2 hub with 28H. Finally some will say that there is some drag or loss of efficiency in Over-drive. I haven't noticed it. Perhaps because my hub is still in tip-top working condition.

You want the top range of a 55T ring on a 622 wheel? Easy peasy. 57T ring with the SDD hub on Over-drive. Worth the price of admission for people's reaction as this seemingly docile pony hauls @zz.

What does it look like on the bike? It looks like a regular derailleur drivetrain, plus the clickbox.

https://dl.dropbox.com/s/sn6h8pz8p5t...25_1.jpg?raw=1

18-108GI on tap!

https://dl.dropbox.com/s/7lq62w4havr...2026.jpg?raw=1

If you ride them both at 14mph average both ways, how much slower will the 20"er be? Or, which one will be faster?

Do you see what I'm getting at? I really don't think you're looking at this right; it's only a question of which wheel size is faster after you've controlled for a bunch of variables first. Do you have a power meter?

I do not have a power meter. I am comparing a lightly rolling ride bike trail section that has no car crossings.

I would guess you are joking--If I ride them both at 14 MPH then there is no difference. My first head to head on different sections of this ride. This was a light workout ride for me, I don't run with a speedometer but use Strava on my phone to look at my post ride results.

4.8 mile rolling section with 73ft of elevation change.
700c 16.2 mph 17:55
20" 14.1 mph 20:32

In a short flat section of that same ride with a downhill section leading into it--I did not know where it started or ended while riding.

700c--17.0 mph--4:58 minutes
20" 15.8 mph--5:21 minutes

So my 700c bike is 1 to 2 mph faster than my Stock Xootr Swift. I am going to play with my position on the Swift and maybe try some different tires.

Abu,

That is a really good looking build. I don't understand using an Adjustable stem with all the extra weight. With the ability to move the stem up and down the stalk a little. I am not a complete weight nut but that adjustable stem is probably 1/2 a pound heavier.

I wasn't joking, rather illustrating the point that your effort is the key issue in this type of evaluation. Without monitoring your power output, I would not accept that the Xootr is any "slower" at 16mph. I'm not saying it isn't possible that it is "slower," only that you haven't controlled the relevant variables which would support that conclusion.

Like what I said earlier, the 20incher will be quicker from a stop and go, but the 700c could be faster in the long run or at least more comfortable to maintain the same speed. Then again, it would really depend on components like the drivetrain and tires/wheelset. I went on a bike ride with a hybrid,fixie and a roadie when I was on my Dahon Speed P8 (upgraded to a double crankset older ultegra ~2005) and I got to drop them on a climb in a bridge but on the way back I kinda kept up with them but was struggling to do so. On the flats in the greenway/trail, roadies seem to just zoom by me, of course those are fitter riders and on a lighter/faster road bike set-up. A 53t by 11t geared foldie would be slower to a 53t by 11t geared 700c given the same cadence/effort because of the smaller wheels I think.

I've been seeing you a lot in the forums, and your bike/s are gorgeous! You're in India right? Kinda jealous of the folding bike market back in Asia since there are so much more choices including the fuller-sized/bigger mini-velos equipped with the lockjaw hinge or the "lighter" fnhons! Even the dahons have more variety in Asia.