For fast commuting I recommend a sport touring bike, which is basically a racing bike with eyelets for easily mounting racks. Aerodynamics favor a front “low rider”, mid axle, rack and packs (preferably a small streamlined pair). The Sport Tourer also has a mountain bike style triple ring crank. Add a large rear wedge seat post/behind the seat pack to balance the weight of the front packs. This combo is known to produce a bike more aerodynamic then a standard racing bike, see “Bicycling Science.” Fenders should be used if your area is often wet, otherwise avoided. The wheels should be stronger then a typical race bike; my pick would be a 32 hole front and rear, laced in front with all radials and in back with radials on the drive side for lateral strength where the wheel is dished out, and with a 2x cross crow’s foot pattern with a radial next to it, referred to as a 2x crows foot hybrid, on the non-drive side to transfer torque through the solid axle. Radials with the spoke head on the inside maximize lateral strenght, but the spokes as much in one plane with heads out maximizes aerodynamics which is about 80% of the resistance to motion of the bike. Spoke heads to the inside on cassette side of the rear could get chewed if the chain comes off between the spokes and cassette. For a full blooded touring bike I would use a standard 2x or 3x crow’s foot pattern everywhere and 36 hole rims putting strength above aerodynamic radials. You should use spokes relatively thinner at least in the middle of the spoke for radials to get equal flex with the diagonal, crossing, spokes for a resilient wheel that stays true. I recommend a battery powered light with battery in the seat post pack to aid balancing the front packs; maybe a dual beam halogen light with a small SEALED motorcycle battery, otherwise acid spills in charging will damage the pack and potentially you, connected at the pack with a dual line jack. This battery is a lot stronger and cheaper then the commercial bike light battery. A motorcycle battery charger or 1 amp, trickle charger, car battery charger would be fine at home or work. Now for the rear get a multiple red LED taillight fastened to the seat bag with a screw, washer and spoke twisted around the screw in it’s middle and the two ends in the two bottom back corners to stabilize the pack and light whether it is empty or full. Practice in your head but NOT for real, falling without hitting obstacles or the handlebars tucked to roll on the backs of your hands, with thumbs kept inward, helmeted head to the side, rolling to one shoulder and over – the natural outstretched hand leads to slow healing wrist breaks, see how to fall in Aikido.
Finally add a reflective yellow or neon colored windbreaker or vest to add visibility day or night. Now pick a route that avoids perils and traffic. Safe Cycling is not just obeying the traffic laws.

I solved the traffic lights' failure to detect my bike. I realized that my bike lacked enough steel to have its’ magnetic moment detected even if I ran into the middle of those detecting loops in the road. So I just happened to be at Industrial Liquidators on Convoy in San Diego, CA and found some of those incredibly strong little magnets, there was one that looked like a side slice from a cylinder and weighed about 1/3 ounce, 9 gms. I bought two, $5 each, one for each bike, and put them nearer the back on the chain stay opposite from the chain side – to prevent magnetizing my chain, bottom bracket bearings or rear hub bearings. I have never failed to be detected by a traffic light since that day, and as a result speeded up my commute.

Thanks for the interesting post, good food for thought here as I have been contemplating getting a tourer that will do double duty as a fast commuter.

Although I'm not sure what "front low rider, mid axle, rack and packs" refers to, could you post a link to a manufacturer's website?

My hardtail mountain bike is my primary commuter and it has been slowly morphing into a hybrid. So much so that I'm about to change the handlebars to drops and replace the suspension forks with road forks. Apart from the weight I'm pretty happy with it, just need to get myself into a more aero position as I'm only averaging around 19MPH at the moment. I'm really at a crossroads wondering if it's worth while pursuing further mods on my mtb or starting again with a tourer and maybe relegating the mtb to wet-weather/backup commuter status. I do about 60 miles a day, 4 or 5 times a week. What do you think?

if your riding 60 miles a day, do yourself a favor and get a nice comfortable touring bike or cyclocross bike with all the rack mounts and do-hickies!

i am of course biased because i own one but i think the perfect long distance commuter is the surly crosscheck.

Even on my high racer I set the lights off because my wheels aluminum sets them off if I get it right over the line in the road that shows where they have buried the wire in the asphalt. Incidentally the bottom bracket on that baby is about 3 feet off the ground. So the aluminum rims are the only thing that it can be sensing unless it is the rear dropouts but those are pretty high too.

Incidentally I found a 21 pound 105 equiped road bike with rack eyelets ideal for my 18 mile (one way) commute and then my 24 mile commute when I moved. The cool benefit was I got to train for centuries and stuff every time I commuted because it was the same bike I used for both puposes. I logged about 13000 commuting miles that way without a problem over the last few years. I eventually switched to a bent as my back just wouldn't let me put out enough power on a traditional road bike due to an old injury that only acted up when I was pushing hard.

An example of a low rider front rack is: https://circlecitybicycles.com/bracks.htm or https://www.outdoorsportz.com/BGRCOOO...ml?051602-6628 and example of a more aerodynamic pack is: https://cgi.ebay.com/ws/eBayISAPI.dll...tem=7162266653 and finally a large wedge shaped seat bag is the Trek Pro Pack 1230CC Large Seat Bag on this page: https://www.stifsport.com/gear/select...productid=2149 the front packs add aerodynamic efficiency by shunting air around the turbulant pedal area and breaking the swirling vortex of air coming out of the front wheel/spokes. MIT Press' original "Bicycling Science" discussed the improved air flow of low front packs. Special low rider racks are made to fit a bike with front shocks, but the panniers hit rocks that are over about 5 inches tall - but there is a rack where you can move the front packs up for the rocky trail and back down for the superb balance and aerodynamics- see: https://www.oldmanmountain.com.

Aluminum has no net magnetic moment - it is not magnetic - perhaps your spokes or the magnet for your bike computer on the spokes is setting the traffic loop magnetic detector off. Or perhaps the theshold for magnetic detection is lower on your signals then here in San Diego. A 21 pound racer with eyelets for racks is a Sport Tourer in my book, and a great vehicle for a fast commute. I have not tried profile aero handlebars where you lay forward on your forearms - but my understanding is they are easier on the back as you are better supported on your forearms, but get neck strain from looking up. The neck strain can be helped by a higher stem, but that reduces the aero properties.

Enjoy the best, and survive the worst.
San Diego, CA

Thanks for the informative post, RJOsprey!

I too have settled on a sport touring bike for my commute. It's my own build, started with a lightweight steel touring frameset. Added 105/Mavic wheels with 28 mm tires, drop bar, triple crank, bar end shifters.

One thing that I would highly recommend for fast commuting: a triple crank and a CLOSELY spaced cassette. That way you have a wide range of gears for the hills and when you're tired, but you also have lots of gear ratios close together, so you can always stay in a good ratio and move fast. I use 30/42/52 chainrings and an 11-23 cassette, for example.

I think it is more fun to morph an existing bike then to buy new. But if your basic frame isn't what you want then the morph maybe wasting money, some parts may not fit a new frame. I bought my sport tourer frame stole some components from my old racer and built, rebuilt and continue tweeks, if I had all the money spent over the years I could buy a better bike today - but I have all the joy of those years and the smile.

I use a GPS instead of a bike computer so I don't have a magnet. Could be the spokes though. There is one sensor I have trouble setting off but I think that is mostly as you can't see the line to park over as they paved over it recently. I thought the induction circuits worked like a theramin. I can make a theramin work but I am not necessarily magnetic. Even aluminim transmits electricity. Course I am probably just talking about stuff I don't understand.

The aero-bars made it worse as the injurey was in my lower back. My average speed has jumped several miles an hour and I am able to push as hard as I want without backpain which was something I couldn't do for more than 20 minutes before (got real annoying on long hills and long rides) going to the recumbent. From the first ride it was night and day for me. Don't think it is everyones solution but it was for me.

In a sense a thermin is like the traffic loop detectors, but a thermin is multiple loops with better electronics and sensitivity. I like Ms Alice Malloy's bra thermin - sounds a lot better then a guy beating his chest. But a moving magnet induces a voltage spike as its moving magnetic field cuts across the stationary coil in the road. Thus while a loop of metal or flat metal is detected the magnet increases the magnetic field of the coil of seat tube and rear stays. One could lay their bike down in the middle of a loop to get it to detect the bike better. Also the loops of the wheels would aid an induction change in the loop even if non-magnetic but current carrying aluminum. But the magnet aids the detection. Ultimately some engineer may have set detection to low to detect many bikes so as not to detect a truck in another lane.