We don't do 30 on the flat very often, but we can pull at 24 when we're in good shape. That's down on our aero bars. We can use every watt we can get. Our oversized PRO4 tires don't look so stupid on 23mm rims. I think just replacing the front with a Kinlin and CxRays made a little difference on the flat. The bike seem to run just a little free-er. I'll do the rear when I wear that rim out, not too long if it keeps raining.
Regarding bead roll off...your experience is with off road? The folks at HED tell me that it's perfectly fine to run at moderate versus high pressures on their rims due to the design of the bead shelf. I'm running 70psi-f/85psi-r on 28mm tires that spec to 110 psi.
Last edited by UnfilteredDregs; 03-07-14 at 04:49 PM.
Poetically vacant... -U.D.
Maxxis UST Tires(variety) plus a few other brands
Note for tires to get UST designation tires must go on by hand and inflate without compressor, and hold air without Sealant.
I found that inflating to max helped seal tire to rim, and as a habit I would try to inflate nite before if I changed tires for conditions.
Also, note that due to roll offs in cross I switched to tubulars.
FWIW, the 700 X 23 Schwalbe tubeless tires show a pressure range of 70-120psi on the sidewall. I am happy with 90/95. I have ridden the wheel hard on my single and it feels great, corners extremely well. I have also ridden it hard on the tandem with absolutely no issues. So far so good!
We now have over 300 miles on the Schwalbe One tires and give them 2 thumbs up. As soon as the tubeless 25's are available here in the US, I will upgrade the rear wheel on the tandem to tubeless and move the tandem wheel to my single. I have converted the front wheel of both of my bikes to tubeless and will eventually update both rear wheels. I do however have some tires to wear out first.
We have just a few rides on our 28 mm Schwalbe One's, but both captain and stoker agree that they have a nice feel. I don't know if we could pass a blind test to differentiate between the Schwalbe One and Ultremo. They do provide a robust, confident feeling.
The whole point of Schwalbes is their availability in 28 mm, whereas the Continental GP4000s is not (yet). Choosing Schwalbe One's but selecting 23 mm is like going back in time to purchase a MKIII AC Cobra, but telling Shelby that instead of the 427 cubic inch FE V8, you'd like a 170 cu in straight six.
Avoidance of pinch flats is an excellent reason to go to 28's.
28 mm tires: Get them for the pinch flat avoidance; stay for the ride comfort.
In the past 15,000+ miles of tandem riding we have NOT had a pinch flat, front or rear. 23mm or 25mm tube or tubeless therefore for now I will stay with the 23/25 setup. The 23 on the front is supposed to provide a slight aero advantage. We are happy with the ride comfort!
Of course, Wayne-DubT is riding 19mm rims (HED) vs. Will-Ritterview riding 22mm rims (ENV Classic 65?). Big difference in wheel specs.
Increased air volume = comfort and lower required pressure. Tubless has more room (no tube) for more air, so less pressure needed. A wider rim also allows for more air volume so it too can achieve comfort and a lower required pressure.
As a direct comparison, we moved from 18.5mm Spinergy rims with 25mm Conti 4-Season tires pumped up to 116-118psi. This pressure was necessary to retain the tire shape especially during hard cornering. The Spinergy rims were the narrowest we have ever had on a tandem. Now we are riding 23mm Kinlin 279/BHS472 rims with the same 25mm tires & tubes pumped to a firm but more compliant 105 psi. Cornering is actually better as the tire does not tend to deflect and it has a larger contact patch providing more grip (not to mention having a significantly laterally stiffer wheelset which track infinitely better). Surprisingly, we are feeling less road surface vibration with the new stiffer wheels vs the Spinergy, which I attribute directly to the reduced tire pressure required with the wider rims.
Bio specs: our current team weight is 265lbs + 30lb tandem. Other: euro touring (unloaded) we use 28mm tires to help span the varied surfaces (gravel, cobbles, etc) we encounter there.
Now to spice things up vs. the Schwalbe One is the Continental GP 4000 S II, analyzed here.
It comes in 28 mm in black and reflex.
A table at Slow Twitch I think shows that the 28's have the least resistance. Is this really for a 50 kg rider? Or is that 50 kg on maybe the rear tire? So with our 28's we are not only reducing the risk of pinch flats, and increasaing ride comfort, we are also reducing rolling resistance. This effect must be magnified with the greater weights of a tandem. We have 140 kg total, figuring 55% on the rear wheel makes it 77 kg.
Finally, letís talk rolling resistance. Similar to the story Iíve heard from Specialized and Schwalbe, Continental says that larger tires roll faster. Hereís a breakdown of their four width options in the GP4000 S II (Crr on the Y axis, pressure on the X axis)
^^^ yes, they are providing their rolling resistance stats based on a 50kg load on a single tire.
The GP 4-Season is also listed as a Conti "race" tire, and supposedly a slightly heavier version of the 4000. This one has "2-layer Vectran™breaker and DuraSkinģ sidewall reinforcement", otherwise the specs and performance are closer to the 4000 than the cheaper Gatorskin (lower tpi, much heavier, etc). No mention of the "Chili" compound on the 4-Seasons.
If you are concerned about blowouts, punctures, etc, then the GP 4-Season may be a better choice over the 4000. Over the last 2 years, we have not had a single flat when using the 4-Seasons. Now that we are running a lower 105 psi with the same 25mm tires (but on 23mm wide rims), it will be interesting to see how that effects the tread wear pattern especially on the rear tire. Previously, we always tended to burn through a narrow middle strip on any tire we used, but with the lower psi I expect a more even (and increased longevity) wear pattern.
To us, the Conti ride quality is definitely less plush than the Schwalbe ZX. If for example I try to sneak +1 psi more into a Conti, my stoker asks me during a ride if I pumped the tires up harder... and she is usually correct when she feels the diff in harshness. Pumped to a similar firmness, the Schwalbe ZX feel more compliant (smooth) and still have great tracking while cornering hard. However, I have heard from other friends of many more punctures with the Schwalbe ZX than they had been experiencing with the GP 4-Season. So, there is a balance / choice to make...
Last edited by twocicle; 03-24-14 at 03:36 PM.
We previously road 28mm tires and have moved to 40mm width kelvar bead flexible tires with a 3mm thick road tread similar to road tires discussed above. They roll fast, corner well and provide a smooth ride. Conti and Schwalbe are not in that tire market. Biggest downside is that most bikes can't run tires that wide. Food for thought when designing you next custom tandem. We slow guys are not the only ones that think so. Below is the Blayley's tandem with 42mm tires. Their blog is at: The Blayleys
Blayleys Seven Ti 650B Tandem.jpg
Aero is a concern as DubT point out. This would depend a lot on the surface. The bumper the road the more benefit from lower pressure hence from wider tires. On a very smooth road narrower harder tires should be faster. There is however a huge advantage on a bumpy road to lower pressure. Unlike small aero changes the lower pressure advantage is large enough to be readily seen and causes cobbled racers to ride very low pressures risking a often getting pinch flats on tubular tires in the process.
Last edited by waynesulak; 03-24-14 at 11:39 AM.
Some marketing folks and bike reviewers will have you believe the different grades of materials and butting have a big influence in bike comfort, but IMNSHO, any difference in materials is absolutely dwarfed by different width tires and tire pressure. In a blind test with the same frame geometry and tires, but different materials (steel, aluminum, carbon, titanium), I believe most riders will struggle to tell much, if any difference. But change the tires from 18 to 23 to 28 to 35mm, and I believe most riders will instantly notice a significant a difference in comfort.
This experiment can be tricky in practice though, when many production bikes are not designed for tires fatter than 25mm.
This isn't to say that one cannot fine-tune the ride of a bike with different materials, or butting or geometry, but tire volume differences don't (necessarily) require a new bike, and will likely give a bigger bang for the buck!
New England roads take a beating in the winter. Snowplows and the freeze-thaw cycle do their best to rip up our roads. Anyone who has ever ridden BMB can confirm that the roads can be brutally rough (and sometimes the pavement is missing completely). Skinny tires, 750 miles and rough pavement on the BMB course will beat up any rider. A 25mm or bigger tires can make a tremendous difference. My recommendation is to mount the widest tire you can get in your frame!