Fat Boy

OK, I did an interesting comparison, and I wanted to share.

I have a Cannondale road bike that's about 5-6 years old that is my normal ride. I also have a 'new to me' 1997 Air Friday. I do the same basic ride over and over on the C'dale. I've been waiting for some parts for the Friday, which is getting prepped for travel duty. So, I got my seat, seat post, tubes, and Primo Comet tires delivered and installed.

I have an older cyclo-computer on the Friday that gives me speed/time/average. On the C'dale I also get cadence. They are different computers and since the tire sizes are different and I'm not 100% sure of the calibrations (I used Sheldon Brown's chart for both, blame him) that is a possible variable. I'm pretty consistent in that I like to spin from about 90-100 rpm. That's probably not a big variable.

The Friday has 62/52 front chainrings and an 11-23 8-speed cassette. The C'dale has 53/40 front chainrings and an 11-27 9-speed cassette. Gearing isn't a huge deal. I run both in the big ring unless I'm climbing and generally in the lower/middle part of the cassette.

So, my average speed on the C'dale for my 'normal' training ride is from 19.5-20.0 mph. I have averaged up to 20.3, but that was with favorable wind conditions. The path of the route I take tends to cancel wind effects, but there still seem to be more and less favorable conditions.

Today on my Air Friday I averaged 19.2 mph over 20.1 miles. I was carrying all of my normal stuff with me, so no real variables there. I did have a real tough workout yesterday that was 30 miles with 10 of those being _serious_ climbing miles. I definitely was not 100%. The wind was blowing in it's least favorable direction, but it wasn't really all that strong, so it didn't skew the data too badly. If I were going to guess, I would guess that on my C'dale today I would have averaged 19.5 or 19.6 mph.

So with a completely un-scientific analysis, I'd say that the Air Friday is about 0.3-0.4 mph slower than my C'dale over a 20 mile ride.

I will also say that there were a couple of things I noticed. The Air Friday is a much smoother ride. There is one section of asphalt that I ride on which has a rough, exposed chip surface. The C'dale gets a lot of aluminum buzz over that stuff. The Friday didn't even know it was there. There is another section on the ride that goes over some older pavement with small potholes, frost heaves, patches, etc. Again, the Friday was much smoother. The front might pop up a little over a patch, but the rear beam would completely soak it up. There are many sections of this second section where I'll stand on the pedals for an instant as I go over the bump. I didn't do this at all with the Friday. It just wasn't necessary. On 1 particular spot there is a compression bump at the base of a short, steep uphill. The bike really loads vertically at this point. I wasn't even thinking about it, but I put enough load in the Friday's beam that it made a hlel of a noise. I initially thought I broke one of the bolts that holds it in. Everything seemed fine for the rest of the ride, though. Just something to be aware of....I should have been on the pedals, not the seat for that one.

So there ya go. It was an interesting little experiment and one that I might repeat for scientific purposes. I thought y'all might be interested. If I have any parting thoughts, I would say that if this were a 5 hour ride instead of a 1 hour one then the Friday might have faired a little better just because of being a little nicer to it's rider.

spambait11

Interesting findings, FB. Just a couple questions: (1) what are the weights of both bikes, and do you think this made a difference? (2) You didn't mention any pogo-ing effects of the Ti beam, so I assume that was a non-issue, or you've somehow gotten used to it?

Less than 1/2 mph is pretty comparable. Hm. Maybe the "bigger wheel is faster" theory is overblown.

vik 

Less than 0.5 mph is too close to call if you haven't calibrated your bike computers. You can measure the roll out on both bikes fairly easily and see if your programed values are accurate. If not you'll be able to adjust them.



The only other Bike Friday that interests me besides my Tikit is the Air Glide. I have a Cannondale R800 which is a fun/fast bike, but it would be nice to have that Ti beam to smoothen rough pavement as you note.

Enjoy both your bikes.....

jur

I found the very long carbon seatpost (400mm) on my Swift does the same thing - buzz just isn't there. It is super smooth.

Fat Boy

Agreed, which is why I mentioned it in the spirit of full disclosure. I just used Sheldon Brown's numbers to get a quick and dirty start. I just Google Earth'd my path. It shows that I was about 1% positive on distance, so that means that my was about 0.2mph slower than my computer showed. When I get my Garmin, I can get more scientific.

----------------------------------------------------

The weight of the Friday is a little more than my C'dale. It's probably 23 pounds and the C'dale is probably 19. The path I took was very flat. I honestly doubt it was much of a factor in the overall comparison. Something I forgot to mention was that I rode in the drops pretty much the entire time on both bikes. That, too, is pretty much a non-player.

In terms of the Ti beam 'pogoing', this was something that I was concerned about when I bought the bike. It's really a non-issue. I don't believe I have anything special in terms of a smooth pedal stroke, in general, I'd say I'm a hack. It doesn't bug me at all. In fact, until you mentioned it, I had forgotten about it.

I do think there is an advantage to a 700c tire. I know there are debates about it, but I feel the advantage is there. Having said that, when you get a narrow, high psi tire on a good bike (folder or not) that has the gears you need to really crank down the road, then make no mistake about it, you can go pretty well indeed.

scarabeoguy

I also have a C'dale tourer, and a Bike Friday Air Glide. For me the Air Glide is much smoother. In fact it is the most comfortable bike I have ever ridden and that includes recumbents. However, the Air Glide / Air Friday is not really a folder in the technical sense. But I did not buy it for that. To me it's my prime touring / long distance mount.

vik 

Bike computers are very accurate for speed & distance when you calibrate them. Why not measure the roll out for each bike and enter that value into your bike computer? Then you'll be able to compare the results directly. Shouldn't take more than 15mins for both bikes.

Fat Boy

Somewhat of a side-note.

I went out again last night on the C'dale. The wind was in the same direction, but this time blowing like crazy. At one point on my final leg home it was directly into my chest. I was in the small chainring and grunting to do 14.5 mph. It sucked. I had recovered much better than the night before, so I was doing a better job. I averaged 19.5 mph. I took note of the distance on my computer vs. Google Earth. The computer on the C'dale was within 100 feet over 10 miles. It was probably just several errors cancelling each other out, but the accuracy of it really surprised me. I've changed the calibration on the BF a little to compensate.

While the Air Friday isn't a quick folder in the sense of my Downtube, I did pack it in a suitcase last night with my SPD shoes and helmet for my trip tomorrow. It does a pretty amazing job of getting small.

Fat Boy

In short, sloth. The proper way to do it is to make a mark on the pavement and tire out in front of my house and then walk with the bike. At 10 revolutions make another mark. Measure the distance between the marks and divide by 10. That takes a lot of the measurement error away and would give me a very accurate number. I guess I just haven't worried about it quite that much.

Like I said the B.F. was about 1% long. I've redone the calibration on that computer to line up with the C'dale. In all honesty, the important part is that those two are the same. It's more of a precision thing rather than accuracy. Having said that, the accuracy of the C'dale is pretty good, as noted above.

Bacciagalupe

I think your "tests" are good enough to give you a basic idea that both bikes are about equal efficiency. While cyclometers are reasonably accurate, the "average" feature is a notoriously poor way to measure performance. There's also a bit of the New Bike Syndrome, where the new wheels will feel faster just 'cause it's a new bike. And I agree with Vik that you've got a big margin of error there.

A *slightly* more reliable test would be as follows:

- pick your testing route, preferably at least 20 miles of uninterrupted riding (e.g. a loop in a nearby park)
- use a stopwatch to track your times
- do at least 2 rides with each bike, preferably 3
- compare

Unfortunately, even with this method you're going to run into lots of environmental and effort variables -- temperature, wind, hydration levels, rest / recovery levels, training phase and so forth.

I.e., I have my doubts that you will get a more accurate test than what you've already done without resorting to a power meter.

That said, I would not be surprised at all that the BF Air is about the same level of performance as a high-quality road bike, particularly if you set up the position properly. If anything, riding position will probably have a bigger impact than tire size in terms of your effort & efficiency.