Thank you both for the excellent history lesson.

I find my Moulton TSR 30 to be just a little slower than my conventional road bike.

Measured (eg. GPS) or perceived?

Curious on this one given what appears to be very similar riding positions, broad range gearing, and clipless pedals.

Measured, but only by way of monitoring my average speeds over various rides using my Garmin 500. I have not kept records, but after two seasons of alternating between the two bikes, which are set up with identical positions and pretty similar gearing, I find I am somewhere between 0.5 and 1.0 mph slower overall on the Moulton for a given course. My rides are almost all solo, and my average speeds range from about 14 mph to about 17 mph. Climbing amounts are in the 50 to 80 feet per mile range most of the time.


FWIW, the Moulton is 5 lbs heavier. It uses Panaracer MiniLite tires that are 28mm wide. I am on 28mm wide Clement Strada LLG's on the Spectrum.


Gear range on the Moulton is 98 to 25 gear inches. On the Spectrum it's 110 to 29 g.i. (The pic of the spectrum is old; I have a triple crank on it now). The difference in the top end is not very meaningful because I can't remember the last time I pedaled above 28-30 mph or so.


On the road, the performance difference doesn't seem to be in any one particular area (flats, climbs, etc.). Although I can say, when climbing seated, they feel similar, but the Moulton is not good for out of the saddle climbing (front suspension bob), but that's not a big deal since I don't stand much anyways.


My gut says the Moulton has to have slightly higher Crr due to the smaller wheels, and probably slightly higher CdA too (due to the wide and wind catching space frame). But the right way to figure that stuff out is to do some Virtual Elevation type roll down tests using the auxiliary speed sensor I have for my Garmin. I just haven't bothered.


The only unfair disadvantage the Moulton has is that it has fenders and the Spectrum doesn't. The fenders are compact and well fitted, but I am sure they are adding some drag.


Something else to keep in mind is that you can draft (and be drafted) a bit closer on the Moulton with the smaller wheels.

I should add that I enjoy riding these two bikes equally well. They feel pretty different, but I guess that's the point and why I have no intention of getting rid of one. I like variety.

My Ti Swift feels the fastest of my bikes. I am convinced it's because it's the lightest bike. Any bit of slope and extra mass slows you down.

On my now-defunct blue Xootr Swift, I sometimes rode with a peleton as training for a big Audax ride, and I found I could keep up just fine except in one spot where there was a long, steady climb, I would tend to get dropped near the end. I recognised that was a fitness issue not a bike issue. On the same ride, in a spot where there is a steeper climb, I would be able to drop other guys again. And in one memorable long downhill, in the middle of the peleton, all of us tucked down, I reached 84km/h.

So I have never felt the bike was an issue, although I can't be as fast on all my bikes. Often people will ask me if the smaller wheels are harder to pedal, mostly I answer no, but sometimes I poke a bit of fun and say ah yeah, much harder.

Thanks for sharing that...

When it moves offroad, the 20" wheels will be even slower?

I'm 56 and 190 lbs

Giant Defy Advanced III - Carbon Road Bike - heavily customized down to 17.4lb Cadence 80 - Heart Rate 140 21mph average

Giant Expressway II - Customized with giant chain ring, extra tall seat post, carbon saddle, DuraMax clip pedals, drop aluminum handlebars (no name - in the box of stuff). Aluminum Folding Bike 21lb Cadence 80 - Heart Rate 140 18mph average and a lot of wasted energy in the flexing of the frame! I can go about 20 miles and then have to stop!! :-) But it folds and goes in the plane.

More details here:

https://www.bikeforums.net/19175072-post377.html

and

https://www.bikeforums.net/19175095-post378.html

I've always noticed my 20" wheeled bikes accelerate slightly faster than my 700cc carbon Specialized but the 700cc hits a higher top speed. But only slightly.

Bike Friday and Trek 5200. Light wheels on the Friday. Same ride of 42kms, 4 times. Road bike consistently faster by 2.4 kms per hour. Still love riding the Friday most, but those are the stats.

For the past seven months I have been a Jimmy John's bicycle delivery driver. I am 20-25 years older than almost all the other bikers. Earlier this week while I was a mile from the store, I found myself half a block behind a coworker that rode a single speed 700C bike. I did not try to close the gap, instead I tried to keep the gap constant until we got into downtown. Once in town I was able to hop curbs, ride on the sidewalk and turn on a dime ( to get through red lights ). I beat him by at least 30 seconds.

The 700C single speed bike was faster on long flats, but my folder was much faster in town. FYI the other biker is super fit, he's a certified personal trainer & an athlete.

Thanks,
Yan

Bigger wheels have an advantage on rough roads.

On smooth pavement, its close enough that rider ability will be the limiting factor.

Here is another take on the comparison:

1963 Moultons beats big bikes!LOLs

To the end of the block one is no faster than the other. But on long rides there really is no comparison, 700c bikes are faster. I ride both types, one is a 20" Birdy folder with Ultetra hubs, and a Dura-Ace/XTR 22 speed driveline. My road bike is a steel-framed Gios Compact Pro with Record carbon 10 speed kit. Both bikes weigh the same, and have the same cockpit dimensions, but the Birdy is not remotely as efficient or fast. That said, the Birdy is a fast bike, but "fast" is a relative word.

Racers have been using 700c bikes for decades, and not because smaller wheels are faster. You'll sometimes see old time trial bikes with 650cc front wheels, but this was done for aerodynamic efficiency rather than because the smaller wheel is faster.

I've raced in the pro peleton, and the thought of trying to keep up on any 20" bike is enough to make me laugh.

But I ride my Birdy much more than I ride my road bike. On the big scale of things, it's not fast, but it is fast enough for me now.

Sangetsu, what tires do run on your Birdy?

I run Panasonic Minits Lite, 20x1.25" with Panaracer R'air tubes at 110 psi. Tires are 170 grams, tubes are 59 grams.

Cool, my favorite tire.. I have them on my Moulton ..

I thought the reason all road racing is done on 700c bikes is because the Uci has limited race bikes to that wheel size.

Well - that's a bit of an invalid argument. In the first place there are no small wheelers in official competitions because they have been forbidden to take part in those races 50 years ago. Not because they would be slower but because they would possibly be faster (as proven by Mr. Moulton and his mates). There are no recumbents in these kind of competitions either as those have also been forbidden (as early as in the 1930ies) - because they were massively faster than conventional road-bikes (and still clearly are). Aerodynamics are not the least reason for a bike being faster in a race btw...

There's enough evidence through the various records held by moulton bikes that this laughter may be misled. A Birdy is not designed to be a race bike, some moultons are to a degree. As small-wheelers are not allowed in official races there is no point for manufacturers in developing small-wheelers dedicated to racing. Still at least the Moultons seem to be more than competitive though having a huge disadvantage in weight. If the same effort towards developing a dedicated racer that went into conventional bikes was put in small-wheelers I could imagine they could be more than competitive. We will never know.

I am sure there are fast group rides in your area, take your small wheeler and see if you can keep up. I've ridden a lot of bikes, and done more than a little competitive racing. My Birdy weighs 18 pounds, has the same components you would find on any $3k road bike, I have even set it up so the riding position is identical to my road bike, same saddle, same pedals, same bar width. It is very fast for a folding bike, but it cannot touch a road bike in regards to speed, and the difference is not small, it is huge. On a road bike, I am a competitive rider in any group, on a small wheel bike, I can't even keep up with the B team.

Racing associations didn't adopt the 700c standard because it was inefficient, or made the bikes slower. It has more or less boiled down to be the optimum size for racing. And a standard was needed so spares could easily be supplied. But group rides have no wheel size restrictions, you are welcome to see how your 20" bike fares against the big boys. If anyone else here has tried it, it would be interesting to hear your experiences.

+1
My observations are the same.

I am at least 1 rider tier lower if I am on the small wheeled bike, while on my road bike, I am in the peleton and even sometimes at the front.

Interesting discussion. I have never raced but have ridden a few times with a peloton. On my Swift. So I can't really compare. I have had the impression my Birdy was slower than my Swift, in fact every other bike is slower than the Swift. With the Swift I never had the idea that if and when I got dropped, it was the bike's fault. But again, I don't have the direct comparison you have.

Any idea why your folder is slower? One guess would be slightly more rolling resistance in the smaller wheels, although records are routinely set on smaller wheels so that does not stand up to scrutiny. Maybe the frame soaking up energy?

If true, then there would be no reason for UCI to make small wheels illegal. No one would use them.

I've used both. It's hard to control for all of the factors -- my NWT is a touring bike and at least 5 pounds heavier -- but my club and training ride times were remarkably close.

@ sangetsu: I think it would be too simple come to the conclusion that small wheelers are generally slower than 700cc bikes from the experience with one single bike. You could race i.e. your Birdy against a crowd of 700cc-equipped dutch bikes and then claim that small wheelers are faster ten 700cc bikes. Or you could say "folders are slower" (as your Birdy is also a folder). There is a whole range of different 700cc bikes as there is a whole range of different small wheelers. And there are a lot of 700cc bikes developed for racing and (to my knowledge) not a single small-wheeler. Moultons with drop-bars are mostly more in the randonneur's class, not so much in the racing class. Jur's ti-swift may be close to a racer (I do not know). But for sure a Birdy frame is not a racing-bike frame plus one single birdy with one single rider cannot speak for all small wheelers (including those small wheeled dedicated racers that have never been developed thanks to the UCI) and all riders. What you have is a single experience with a bike based on a touring-/city-frame (no harm intended) and there are people out there that have made an opposite one with small-wheelers vs. 700cc. Personally I am no racer, I am cycling for transport. Therefor no real-world-experience from my side on the topic. But clearly there are the various Moulton-records and race-successes. And there exist i.e. small-wheeled recumbents. Supposed those were quicker than a 700cc racer - what would then be your conclusion? Or, to stay in the class, you could pimp a big-wheeled folder in the same way you did with your birdy to even out chances and then try out which bike is faster. Still there would be no general judgement possible if you ask me.