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Comparison of Beam Bikes
"This article compares four designs: Softride, TitanFlex, Air Friday, and Thudbuster seatpost. No recommendations are provided, only information to help you decide what's appropriate for your own riding."
by Terry Zmrhal
Terry Zmrhal is the UMCA Records and Events Calendar chair. He qualified for RAAM at Furnace Creek and is a veteran of Boston-Montreal-Boston, Paris-Brest-Paris and Bicycle Across Missouri.
Over the past six years, I've ridden over 16,000 miles on various bike designs that provide suspension for the rider. This article compares four designs:
No recommendations are provided, only information to help you decide what's appropriate for your own riding. (Other suspension designs are available and include Zipp, Kestrel, Trek Y-Foil, rear suspension mountain bikes, and other suspension seatposts.)
All suspension designs share three traits.
- Road bike suspension designs will provide a more comfortable ride. The caveat is that you must have a saddle that is comfortable and fits you. If not, no amount of suspension will help - just ask Muffy Ritz.
- The feet, arms and upper body generally take more abuse than normal. The energy of the bumps and rough spots has to go somewhere: the suspension absorbs most of it, but the rest tends to be dissipated on the frame and body. The upper body may be more fatigued after riding one of these bikes.
- Finding one of these bikes to test ride may be difficult. The best suggestion is to find someone nearby (most companies can help with this) or attend an event like PAC Tour or Hell Week where you may find someone with the bike you are interested in.
Softride Softride bikes use a carbon fiber beam designed to "suspend the rider rather than the bike." Since a seatpost isn't necessary, the frame of these bikes has been designed to accommodate the beam. The Softride website has useful information about their beam design and bikes. The Ride On my first ride, I went over railroad tracks and wasn't bounced out of the saddle, though I still felt the tracks in my arms. I started looking for rough sections of road to feel what affect the beam would have. I was amazed at the difference. Most of the roughness of the road disappeared. The bike felt amazingly comfortable and stable. The beam also had the effect of making corners seem easier to handle. Instead of the rider bouncing through rough corners, the body stays still and the wheel and beam handle the roughness. Going around corners also produces a natural outward force (the bike wants to keep going straight). As a result the beam compresses and the center of gravity of the bike lowers a bit, producing more stability. It feels really cool in a fast, tight turn. On the first few rides on a Softride you will likely bounce. The bounce is because the beam itself is responding to your body movements as you pedal. The more you ride a Softride, the smoother your pedal stroke will become thus reducing the bounce. If you watch a rider with a very smooth pedal stroke on a Softride, you will still see the beam will still bob just a bit. The Softride has two noticeable disadvantages. The first is weight; the beam weight adds about 1.5 pounds over the use of a normal seatpost. Second is a reduction in standover height. The beam adds about 1.5 inches to the top tube height. I bought a 52 cm Softride (I normally ride a 55 cm) and still had some trouble standing over the bike. Of course the idea is to stay moving and not stand around very long. Pros Cons Summary
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Air Friday The Softride was very comfortable, but it was difficult to overcome the weight penalty. The next step was a Green Gear Cycling Air Friday. The Air Friday is a folding bike designed to fit in a suitcase through the use of 20" wheels, hinges, and creative engineering. Even with the unusual design, all the dimensions are the same as a regular road bike. The weight penalty for the hinges is small; a complete custom fit bike weighs around 21 pounds. The Ride Unless you look down, you will forget you are riding a folding bike with 20" wheels. It rides and handles just like a regular road bike. The bike has been designed to have the same dimensions as a bike with 700c wheels, but with different tube placement, hinges, and overlaps. It accelerates and climbs a little better with the smaller wheels; on the flip side you won't maintain as much downhill speed because the 20" wheels don't sustain as much momentum. Standing can be a little odd the first couple times with the smaller wheels; the bike can feel floppy. Stability is amazing; riding with no hands or with aerobars is a breeze. The titanium beam/boom provides suspension. The beam doesn't provide as much suspension as the Softride, but it comes close. The Air Friday picks up the little bumps and the big bumps equally well. It does have a quick rebound that can push you off the saddle. The quick rebound is because of the properties of titanium which bounces back quickly after being deflected. On the Air Friday, I didn't feel in my arms and feet as much of the chatter of chip-seal surfaces as I did on the Softride. Part of this is because of the long stem and part of it is that titanium seems to absorb more of the road bumps. The bike definitively has extra weight for the hinges and for the overlap of material for disassembly purposes; still 21 pounds for a complete bike (sans bottle cages, pump, etc.), is very respectable. The only real drawback to the Air Friday is some of the components are only replaceable by Green Gear. This is why I have gone back to 700c bikes. For ultramarathon events like brevets and PBP you can end up 'in the middle of nowhere' and you won't be able to find some of the parts for this bike. You will need to call Green Gear to get replacements. After spending months of preparation, I wouldn't want a bike-specific mechanical or part problem to cause me to have to abandon. For everyday riding, this is not as much of a problem. I can't say enough good things about the bike. It can serve as a great long distance bike or add a front and rear rack and you're off touring. Pros Cons Summary
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Thudbuster suspension seatpost Suspension seatposts can and do offer the comfort of beam designs, without requiring a specific frame design. Most suspension seatposts incorporate a spring or elastomer inside the seatpost. While these seatposts can be fairly lightweight, they suffer from stiction problems. Stiction occurs when the movement of the rider (up and down) is not the same direction as the movement of the suspension mechanism (along the seat tube). The Thudbuster uses a parallelogram design with elastomer bumpers above the top of the seat tube. The bumpers are adjustable for different weight riders. The result is a fairly heavy seatpost (1.1 lbs) that requires about four inches between the top of the seat tube and the seat rails. The Ride I recently bought a tandem and wanted to provide my stoker with a more comfortable ride. After researching several seatposts, I bought the Thudbuster since reviews indicated it would provide the best comfort without stiction problems. At first I wasn't certain the seatpost was working, my stoker had indicated she wasn't feeling the bumps but most seemed small. The clincher came on a ride on a very rough road. My arms and hands were hurting from the roughness and steering was tricky to get through the roughest stuff. I asked my stoker if she felt how rough the road was and she said 'No'. At that point I knew it was working. Because of my stoker's experience, I tried the Thudbuster on my rain/brevet bike. My impression is that it works, but you don't know it's working. In contrast, you feel the downward movement of the Softride and you feel the downward movement and quick rebound with the Air Friday. There is no similar experience with the Thudbuster. The only time I've felt the compression is hitting some bumps going downhill. It seems as if the rider stays stationary and the bike moves up underneath you. I don't know if this is actually what happens, but I don't feel the post moving. Still I know it's working because I feel the bumps much less. Pros Cons Summary
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TitanFlex The TitanFlex combines some of the best qualities of the Softride and Air Friday - lightweight, titanium beam/boom for suspension, 700c wheels - without the weight penalty and standover height problems. The frames were originally made of a tubular design (aluminum), but are now only available in a monocoque design (still aluminum). The Ride Pros Cons Summary After all this riding and comparison, I am currently I am ride a traditional double diamond steel frame with the Thudbuster seatpost in the winter and rain (in Seattle this is eight months of the year) and the TitanFlex otherwise. If you're looking for a more comfortable ride and are considering road bike suspension technologies, there are many to choose from. Each has its' own trade-offs. Most importantly, each works well! You need to judge for yourself what's important to you. Good Luck and Happy Riding! Other Riders Opinions TitanFlex Overall impressions: Both the Softride and the TitanFlex reduce road shock, the Softride more so than the TitanFlex. Both bikes are better on downhills than traditional bikes due to the flexing around corners. Suspension bikes will not eliminate prostate numbness in men or crotch rub in women. It is the seat that reduces those pressures, not the bike. You are compromising weight for comfort in the Softride. The TitanFlex combines the best of both worlds-comfort and lightweight. From Lon Haldeman I had one of the original fiberglass Softride beams. It was very springy with about four inches of travel. I never did get used to it. The next generation was much better. I love it on the back of the tandem. The beam as about 1/2 inch of side to side flex which is also nice on the tandem. The Trek F-foil is by far the stiffest, but I still find it comfortable. I think my Trek handles the best but that could be from the overall geometry. I think Softride is on to something with their titanium beam. Like the Titan Flex and Air Friday they should be able to make a lightweight bike that still has suspension. I can't wait to ride one. Now if they only made a one speed version. From Mike Bauman
http://www.softride.com
I've ridden about 5,000 miles on Softrides during the summers of 1994-96 (not practical for fenders), including many centuries, double centuries, brevets, and some of the Furnace Creek 508.
The Softride beam is the most comfortable bike around (with the right seat!). It is versatile and can be used on a variety of bike designs and frame material, resulting in a large price range from the affordable ($600) to the exotic ($3,000+). With this versatility, weight and standover height reduction remain as drawbacks.
http://www.bikefriday.com
I've ridden the Air Friday about 9,000 miles since 1997 including centuries, double centuries, tours, brevets, a 24 hour event, and Furnace Creek.
If I could only have one bike, this would probably be it. It does so many things well - climbing, accelerating, stability, commuting, touring (easy to add a rack), descending, long distance. If I didn't do ultra-marathons and lots of long unsupported rides, this would probably be my first choice for a bike.
http://www.thudbuster.com
I've ridden about 1600 miles on the Thudbuster including PBP.
If you have four inches of clearance between the top of the seat tube and the seat rails and want a more comfortable ride, the Thudbuster is definitively worth a try! A lot of benefit for very little cost and frame requirements.
http://www.ttinet.com/tf
My impressions are limited since I have ridden this bike less than 500 miles. It's very comfortable, but still feels like a regular road bike. The suspension is good, less than the Air Friday, but still plenty sufficient. It too suffers from the titanium rebound where the titanium springs back quickly, but not as much because the length of titanium exposed is less. The front end seems to be a little harsher than the other bikes.
I can't summarize the ride because of the little amount of riding I've done on these bikes. I think the design has great potential and look forward to spending more riding time on the TitanFlex.
From Muffy Ritz
Softride
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I have ridden at least 5,000 miles each on a Trek Y-foil, Air Friday and Softride. I suggest that you ride one for at least 100 miles before deciding. The best test is if the bike and road disappear beneath you while still being responsive.
Professor Softride