TXbikerider

We're enjoying our new Santana Team Niobium. Team weight 330-340 lbs. Came with Rolf wheels and 700x25C Continental 4-season Gran Prix tires. The one problem we're having is rear tire flats. In 400 miles we've had 4 flats, 3 of which were pinch flats. Minor bumps that were no problem on our previous tandem (steel Santana Sovereign running 28C Continental Ultra Gatorskins on conventional 48 spoke wheels/rims) are causing pinch flats on the new bike.

OK. I've read a lot of the threads on pros/cons of 25 vs. 28C and my first action will probably be to replace the rear tire with 28C. I think I'll keep the 25C up front to keep weight down (love the acceleration in these lightweight wheels/tires). Any comments on that (vs. going 28C for both wheels) appreciated.

My dealer suggested that Bontrager Hardcase would be better even than Gatorskins due to stiffer sidewall and thus pinch flat resistent. Anybody have experience with that comparison? The Hardcases are heavier unless I go with the X Lite version, but those only come in 25C, not 28C. If you have experience with them, do you think they are so strong (sidewall) that they'll work well at 25C? Or is it better to go with 28C Gatorskins (or other?)?

But my big question is, Is it better to go with a heavier tire like the Gatorskins or Bontrager, or to go with a heavier tube? Something like the thorn resistent tubes available, for example. Seems to me if it is the tube being pinched that's the problem, maybe rather than stiffening the tire sidewall it would work better to thicken the tube material. If we assume equal weight increase, is it better to put the extra weight into thicker tubes or into heavier tires?

Chris_W

One piece of useful information that you neglected to mention is what tire pressure you are using, both on the current 25c tires and your previous 28c tires.

TandemGeek

Does you dealer use the Hardcase on his tandem or has he gotten good feedback from other tandem teams in local area who are using these tires? If not, then aside from assuming a heavier tire and tubes will be more durable, he may not have an appreciation for what the trade off will be in performance, i.e., that nice placebo effect you get with lighter weight wheels relative to acceleration.


As Chris W. implies, perhaps you're not running the 4 Season's at a high-enough PSI. You should be running them at 120psi given your team weight which, coincidentally, is the maximum PSI rating for the Rolf's. Now, if you're already running them at 120 PSI and getting pinch flats then you need a 28mm tire. In which case, you can opt for the 4 Season in a 28mm size (they make 'em, you just need to figure out who has 'em) or just deal with the 70 gram wire bead weight penalty and stick with your tried and true Conti Ultra Gatorskins in the 28mm width.

TXbikerider

We were using about 110 psi at first, then after the first couple pinch flats raised it to 125-130 psi but didn't seem to make a difference.
On our old bike with the 28C Gatorskin tires we typically only ran about 100 psi.

I'm especially interested in any comments regarding putting more mass into tube vs. tire. Thanks!

TXbikerider

Tandemgeek,
I don't know the basis of the dealer's comments other than he said that the Bontrager Hardcase has a stronger sidewall, and I looked up on their website and they advertise this tire as being more pinch flat resistent due to extra sidewall reinforcement. I'd be interested if anyone has experience on these, and if a 25 of these would be better than a 28 of something lighter.

Thanks for the info on max pressure for Rolfs. I didn't realize there was a 120 psi limit. Guess I exceeded that when I went 125-130 psi on the 4 seasons this last time!

Is the durability of the 4 season (28C) close to the Gatorskin, i.e., if we go that route? What about a combination of 4 season with a heavier tube vs. Gatorskin w/conventional tube? Interested in any personal experience or opinions.
Thanks!

rdtompki

We're a 350 lb team running the 4 Seasons on 28mm rims: 120 psi rear, 115 psi front. Haven't had a single pinch flat. I'm guessing we'll get 1500 miles out of the rear tire, more out of the front of course. Around where we ride I don't know that a thicker tube would help. Nothing stop's a goat head and when they mow next to the shoulder those little, suckers are all over the place. We haven't had a single rear flat since the first rain of the year. I was concerned about even the 28mm, but Todd at daVinci said we'd be fine if we kept the pressure up: he was right. I started with Gatorskins, but switch to the 4 Seasons when I started carrying a folding tire on longer rides; I know carrying a spare tire is overkill, but I actually used it when I got a piece of glass in a tire that I couldn't remove. And the 4 Seasons are so easy to get on/off.

Carbonfiberboy 

I'm in the PNW, where it rains a lot. And more than that, it mists even more. As you probably know, that's the best thing for transforming road dirt, sand, and assorted grit into a grinding paste that will wear through your brake track in one season. I've gone through quite a number of rims in this manner, until I figured out the solution for singles: ceramic coated brake tracks. But there aren't any ceramic rims suitable for tandems, at least that I know of.

All this to say that in my experience, the PSI ratings which manufacturers give their rims are based on degraded rim thickness. I know that, because I regularly run 140-145 PSI in tires on 120 PSI rims. When you buy a road tire that says, "Maximum inflation pressure 160 PSI," on what road rim do they think you will run it? In my experience with these high inflation pressures, the rim doesn't start to blow out until it's down to at least 1/3 of the new track thickness.

If you look up the rated rim PSI, you'll see that the manufacturer will give a different rating for different tire widths. 23c higher than 25c, and that higher than 28c, etc. If you work it out, you'll see that they've arranged it so that, if you go by their table, you don't gain anything, pinch-flat-wise, by going to a wider tire. I guess my point is that we are running equipment that is, at base really designed for singles, on very large bicycles with riders weighing over 300 lbs. If that were not the case, our tandem rated wheels would have rims rated for over 120 PSI.

Anyway, that's my reasoning. We're a 300 lb. team. I run either 23c at both ends at 140 lbs., or 23c front at 140 and 25c rear at 130. With this combination, we ridden a couple thousand miles with exactly one pinch flat, which happened because I ran over a large rock in poor light. We have to go over the worst RR crossing I've ever seen every time we go for a ride. No problem. Other than our tandem, I've ridden various singles with various rims over 50,000 miles with these pressures and no rim failures other than, as I said, those caused by wear.

So that's my solution: buy tires with a higher sidewall limit and pump 'em up. You might also check your gauge against one known to be reliable. I doubt that stiffer sidewalls will do much. Push on a deflated tire with your fingers in the store. How much resistance to pinch flatting are they really adding? And how much road feel are they subtracting?

BTW, you know you have a rim problem if your brake lever starts pulsing when you apply that brake. Discontinue use of that brake and take it easy until you can inspect the rim carefully.

TXbikerider

Carbonfiberboy, you live in a beautiful part of the country, but I find it depressing to visit when it is overcast and misting, which is often. Now you've given me yet another reason not to live there--"grinding paste"! LOL Seriously, I would think that disc brakes would pretty much take care of that rim-wear problem for you on a tandem, wouldn't they?

I'm sure you're right about a safety factor being built in by manufacturers on rim pressure rating. I am a cautious person so do hate to exceed the recommended rating, but pinch flats aren't a good deal either, so if the tire design doesn't take care of it, I may have to. Other option is for my team (yes, both of us!) to lose some weight! ;-)

Still looking for some comments on tradeoffs of stronger tubes vs. stronger tires, with respect to which is the most efficient way (weight-wise) to add pinch flat resistence.

WebsterBikeMan

Not definitive, but according to Sheldon Brown:

Pinch flats (also known as "snakebites" because there are usually two small holes in the tube, as if made by the fangs of a snake) are usually caused by carelessness or riding under-inflated tires. They can also be caused by the use of a tire which is too narrow for the weight it is asked to carry.

As indirectly indicated by TG, the amount of pressure you need drops with increasing tire width. There's a handy chart at www.vintagebicyclepress.com/images/TireDrop.pdf.

Of course you have to know your load distribution (riders plus bike) across the two wheels.

Given that Sheldon doesn't mention the possibility of a more robust tube, I suspect there's little to be gained from changing the tube, and everything to be gained by increasing the tire width and/or pressure.

reversegear

As someone who has experienced three front tire blow outs at speed in the last three years I believe you might change your mind about that the first time it happens to you on a twisty road with oncoming traffic.

We tend to put more distance on our stuff than most people do, so I think that we do experience stuff that rarely happens to other riders.

I know that Carbonfiberboy and Tandemgeek will write at length about the advantages of running narrow tires at high pressure. To each his own. Maybe that is the way to go for you too.

Homeyba likes narrow tires on his tandem too since anything wide won't fit that Calfee of his.

I would like to offer an alternative. You can run a wider lightweight tire such as a Grand Bois 30 or 32 with a lightweight tube and not get pinch flats. With a lightweight, wide tire, rotating weight is as low or lower, so acceleration is as good or better than a narrow heavy tube and tire set up, necessary for the high pressures and safety. It may be due to the taller sidewall that even with the lower pressure and heavier team weight I very rarely get a pinch flat.

Of the three front tire blowouts, one was a Continental Gatorskin 28 wire bead, one was a Panaracer Pasela 32, and the most recent was a folding Gatorskin 28. The Gatorskins both blew out after or on steep twisty descents. The Panaracer blew out on the Santa Ana River Trail - flat - no braking - no clue as to why. Might be due to the fact that the Panaracer had a lot of miles on it???

I have found the Grand Bois 30's to be fast, comfortable and reliable with lightweight tubes. We are a relatively heavy team and I do not think we have pinch flatted in the last year.

Some have reported these tires to be less durable. I think that is true. While I would not consider them to be mileage monsters, they will be my next tire purchase. By the way, they very well may be the most comfortable tires out there and have a low rolling resistance on rough roads. Hate to sound like a commercial, but that has been my experience.

As a respected PNW blogger, Dr. Codfish, likes to say, your results may vary.

TandemGeek

OK, that was the text book answer which I was obligated to provide. That said, I've discussed the PSI rating with someone at **** in regard to tires like my Vredestein's that run at 140 PSI. They did not freak out and simply suggested that I not leave the tire's fully pumped up when we were done riding. While I didn't quite grasp why they felt that prolonged static loading was a bad thing, I was encouraged that they didn't flat out say "bad idea".

TXbikerider

My Rolf Tandem wheels are for up to 28c width tires. I read the owner's manual and it says that wider can work but isn't recommended. Not sure why or what that means. Your experience doesn't sound like fun--a blow-out on a steep descent sounds frightening (and possibly very painful)!

Carbonfiberboy 

Note I did not mention running tires at over their labeled max pressure, and I don't. I have had tire failures with some brands, running them at rated pressure, notably the old Conti 3000, which was a truly terrible tire. But I've always noticed the tire going before it actually blew. I have a lot of experience with my Tricomps, and never a problem that I didn't cause.

I thank you and will add the Paselas to my list of tires I will never run, which already contains the Gatorskins. What blew on the Pasela?

I will be wanting to run 28c for a European cc/UL camping tour. I'm leaning toward the Vittoria Rubino Pro Tech.
https://www.vittoria.com/index.php?op...318&Itemid=116
It has a variety of features that interest me in a touring tire. Its max pressure of 115 should be fine.

BTW, I also don't leave my tires at full pressure between rides.

Homeyba

I usually run 25's on my Calfee though I have been known to run 23's on occasion (just cause that's whats lying around). As Reverse gear knows, those balloon tires look funny anyways. I have a variety of stokers so my bike weight varies quite a bit but I'm 240 by myself right now so that makes my team heavier than the OP. I haven't had a single pinch flat on the rear tire of the Calfee since I received it last May. I have had three front flats this year on the tandem all between 40 and 55mph. One in the middle of the night during a rain storm when we hit a pot hole (bent the wheel too!), one from a sharp W. Virginia rock and the last front flat was on a Vittoria 23mm tubular tire when we hit a rock on the famously bad Baker/Kelso rd. If I could keep from hitting rocks and potholes I would probably have had zero flats on the tandem this year. I probably put between 3k and 4k miles on the tandem in that time...three flats isn't so bad.

specbill

TXbikerider…since I currently use the tires you mentioned, along with having experimented with some of the popular tube types here are a few thoughts...…probably a few too many actually.
Last year we ran near new stock 28c Bontrager Race Lite Hardcase tires/tubes on our ’07 Trek T2000 on stock low spoke count Bontrager Race Lite Tandem. Wheels for near 2000 miles.. Last year we also ran 28c Continental 4 Season Grand Prix tires on our C’dale Road Tandem mounted to conventional 48 spokes custom wheels for over 2500 miles…in fact we have run Conti 4 Seasons GP’s for the last 3 + years on the C’dale with a variety of different tubes. including those with slime, the super thin ones, and your basic standard tubes.
We are a 305 pound team (plus the bike), that generally ride on less than ideal pavement…pot holes and stray rocks and junk are common place We run both brand of tires at 100psi front and 110 psi rears.
Here is what our experience has been:
Both brands/models of tires have produced notably less flats than the other tires we have tried in similar sizes over the last 10 + years.
Both brands of tires have produced no pinch flats last year. In fact we have avoided pinched flats completely since landing on the Conti 4 Season GP’s at these sizes and pressures.
Tubes…Over years of experimenting with tubes I have had no conclusive difference in flat frequency with any of the tubes we have used …and ultimately I’ve landed on plain vanilla Forte tubes for the 98% of the riding we do. I gave up on the super light tubes for three reasons: they cost more, their thinness made be nervous and they provided no benefit that I could measure for how we ride. However, on my single bike I do mount up the heavy duty slime filled tubes for any rare long distance rail trail rides I might do for the extra thorn protection peace of mind.
Tire Life: Conti 4 Season GP’s - I consistently get 1500 miles out of the rear before the threads start to show. For the Bontrager’s I was very surprised to only get 1500 miles on the rear tire as well before the diagonal seam in the tread started to show bare threads…since that was my only wear experience with the Bontrager I’m hoping that was a fluke because they look and feel like a heavier tire that would wear much longer.
Handling Characteristics:: This is pretty subjective and is probably influenced by the wheels that each are mounted to but regardless, I prefer the Conti’s by a larger margin for confidence inspiring handling when speeds increase, the road changes direction and you start to stress the Tandem’s turning abilities.
Final thoughts: Based on our weight, and the fact that I like to leave a margin for extra safety and reliability on our Tandems, I intentionally run the larger 28’s instead of 25’s and go with what I consider the best quality tires I can afford.. For the tubes, except for the small exception mentioned, I don’t see much gain beyond .the standard tubes for how/where we normally ride.
FWIW…If I were pinching as frequently as you described, I would go to 28c Conti 4 Seasons and experiment with pressures in the ranges you used before. Good luck!

Bill J.

TXbikerider

Thanks for the great feedback! I think it is clear that 28c is what most people prefer to get out of pinch flats (that, or raising pressure beyond manufacturer's rating). I'll definitely be trying that direction. I'm still trying to learn more about tubes. The more I read, I see that several of the thorn resistant tubes advertise themselves as pinch flat resistant. Is it hype or reality? I also found that Specialized makes an aramid fiber containing tube that is supposed to be thorn resistant but without the heavy weight of other thorn resistant tubes. It weights 110 g for a 700x28. I'm a bit puzzled because Specialized's own webstore has only 26" size for sale and at $4 price ($10 MSRP), so it looks like a clearance sale; maybe they are discontinuing them? Maybe they didn't work? Anyway, I have written Specialized and will see what they say. I may yet try that on 25c tires and also get the 700x28 tubes and try them on 28c tires. The latter would be heavier but more robust.

mkane77g

We use latex tubes, and have been for over 10yrs. Very supple, last for years, really. Michelin Krylon's 25mm 1200miles average on rear tire, 300lbs. combined weight. When we do get a flat, the tires usaully very worn.

Retro Grouch 

We run Continental 700 X 28C Gatorskins @ 110 psi on the rear and don't pinch flat. Team weight is around 380 lbs. We only average around 14 mph so maybe we don't hit the pot holes quite as hard as you do.

coloroadie

We are a 280# team and run 28C gatorskins at 115 psi with great results in terms of longevity (1500-1800 mi on rear tire) , durability (1-2 flats per 6,000 miles with no pinch flats) and performance (sub 5-hr centuries in rolling terrain).

Since we live in the foothills of the Rockies and routinely see descent speeds of 50+ mph, we want the extra seconds that a larger volume tire may provide if something unexpected happens. Also believe the added plushness of a lower pressure/higher volume tire is better for longevity of the spokes/rims.

YMMV.

merlinextraligh

We run 25c's with a team weight of 340 or so. I do not recall the last pinch flat.

3 pinch flats in 400 miles equals :

1) too low tire pressure,
2) really bad luck,
3) improper installation (i.e you're not getting the bead set correctly, anf the tube not pinched to start with.

I vote for 3.

But 2 is still possible.

Butcher

We run with 25c's. Last year are team was 400lbs but this year my daughter is stoking and just with that we lost about 80-90lbs. Tire pressures are 130 rear and 120 front. We have run with latex and butyl and both seem to blow on the rim side. I am using Velo plugs now and have not had a leak since.
I too live in the Seattle area but I am one of those that hate the rain and therefore does not ride in it. Cuts down on the bike rides but since it is always dry, it makes all the other rides enjoyable. I went on my first ride with my daughter and man, loosing 80 lbs is amazing [esp when I live on a 15% grade hill].

joe@vwvortex

After running 28c wire bead Gatorskins for the 5 years I've owned our CoMo - I just switched to the folding 28c Conti 4 Seasons. We have the older version of the Rolf Wheels. The tires were easy to put on but the bead was a bit tighter than the wire beads so I'm not too worried. We've only experienced 1 pinch flat on our tandem in the 5 years of riding and that was after hitting a partially gravel/dirt road for about 3 miles. In fact we've only had a total of 3 flats including that one since owning the bike. One of the reasons I stuck with the Gatorskins. The tandem felt alot better with the 4 Seasons then I expected. I'm hoping they prove as durable as the Gatorskins. We are a 340lb team and I run 115psi +/- in both front and rear.

A friend of mine runs the Bontrager Hardcases on his roadbike and I recently replaced one of his tires as it was worn out. It does have a very stiff sidewall.

TXbikerider

That's exactly the configuration I've decided to try, though also getting some heavier tubes to experiment with if I keep having problems. Your team weight is the same as ours, and we'll have Rolf wheels with 28c Conti 4 Seasons. I flatted yet again yesterday, though this time not a pinch, but this is getting old!

TXbikerider

P.S.--I don't have the 28c tires on yet. Still waiting to receive them from Bike Tires Direct.

joe@vwvortex

Are you flatting on the same wheel? Have you checked for anything in the tire?