merlinextraligh

The 28mm Continental 4 Seasons that came with our bike are already shot.

So the plan was to replace them with 25mm Continental 4000's (which the bike was supposed to come with originally).

The LBS didn't ahve them,and couldn't readily get them so they put on 24 mm Continental Forces front and back.

The Force is marketed as a rear tire, paired with a 22mm Attack.

The LBS's thought process was that at 24mm the Force would be wide enough for our team weight (345lbs and hopefully dropping.)

I have 2 concerns; 1) pinch flats, and 2) cornering, given that the Force is allegedly optimized as a rear tire only.

We've ridden them about 125 miles and they feel good. In fact they feel very fast (which might be affected by the fact I haven'te recalibrated the computer yet.).

Sevenrider

In May I put Continental Force tires on my tandem that I keep in California. We put 200 miles on them and didn't have any problems with them. Handling was fine.

specbill

I have to say I'm a bit nervous for you on these new tires knowing how hard you ride and that you do hill training with step downhills that really load that front tire. If you were a light weight, weekend flatlander team then no big deal but you guys are not. I'll admit to being on the conservative side in general but I would recommend gettig to Conti's tech people and get their blessing before punishing the Attack or Force tires on a Tandem. I have no doubt that they roll qiuck with a lot of air in them but I worry about side loads on down hill bends on unknow surfaces with an aggrtessive Tandem team......that is real high risk stuff!
Regarding the 28mm Conti 4 Season tires....We (305 pound team plus the bike) have had great reliability and stability with these tires in mountainous conditions although we probably do not stress them as hard as you.
Have considered going to the 25's but ...we're not racers and I prefer a little more margin for safety. The only down side to these is the rear tire wears out fast...it squares-up at 1500 miles and I replace then at less than 2000. The front gets twice the wear of the rear but I replace it anyway. I justify the replacements as cheap insurance knowing the possible consequences.
When you say "they are shot already" is it tread wear or something else?

Bill J.

merlinextraligh

The rear was worn to the threads in 1200 miles. The front still has a little life.

We're doing Brasstown Bald this weekend so that will be the acid test.

mrfish

I would try some Pro Race II 25mm tyres. These are a good bit wider than the 24mm contis and wear better than the Contis without going square so you tend to get more life out of them. They provide a similar excellent ride and great grip in slimy conditions. If you want a bit more tyre life then the Michelin Krylions give many more miles and excellent cut resistance for only a tiny reduction in ultimate grip. I have tried 23mm and 25mm tyres and would stick with the 25mm unless riding on the sort of billiard table roads I've only seen in Germany.

All that said, these are all road racing tyres so when you double the load and torque, they aren't going to last for ever so you need to regard them as consumable items.

merlinextraligh

Ok, you guys have scared me enough that I changed the Force tires out to 25mm Conti 4000's. ( One of the forces is already in use on my single)

The 4000's are nominally 1 mm wider. However to the naked eye, I can't see any difference.

We put about 100 miles on the Force tires with no issues. We'll see how the 4000's work.

By the way, if anyone is looking for a high performance tire, the 25mm Conti GP 4000 in black is essentially the same tire as the 4000 S.

The 4000s gives you the Black Chili compound which supposedly enhances grip. The 4000s isn't availablein a 25mm. However, the black on black 4000 in 25mm has the black chili compound, and is essentially a 4000s, albeit not labeled as such.

dvs cycles

I've been very happy with the 25c GP-4000's. Much better ride and rollout than the 28 Gatorskins that came with the bike. Have 1000 miles on them so far and barring road hazards looks like the rear will go to at least 2000 before the wear indicators say it's time to replace.

specbill

Good man...giving you and the Mrs a little more margin in the mountains is a wise thing, ' can always use those go-fast skinny devils in a nice flat time trial.....enjoy Brasstown Bald this weekend.

Bill J.

Hermes

Our tire experience...278 pound team plus bike.

Conti 28 mm Gatorskins - the bike came with these and they were fine.

Conti GP 4000 25 mm - I installed these because we wanted a "lighter more responsive tire" for racing. We liked the ride but the GP 4000 unraveled so that I was cutting off black strands. Not knowing exactly what this meant but assuming it was not good changed to the Michelin Pro II.

Michelin Pro II 25 mm - We liked these a lot better than the GP 4000. Qualitatively the ride was better than the Contis.

Conti GP 4000s 23 mm - We installed these with the idea of having lower rolling resistance and a faster tire for time trials. The ride was good and the tires seemed fast - both qualitative measures. At the District TT Championships, the rear tire blew off the rim at the starting line. Since we were ready to race at the prescribed time, the starters gave us 5 minutes to fix the tire and start. 5 other racers converged on us and the team repaired the flat and we raced. You will note that no one was going to let us not suffer a 40K TT.

My wife rode a 20 K TT with the women at 8AM. I took the tandem off the car at 8 AM and the temperature was 45 degrees at an altitude of 5000 feet. I pumped the tires to 125 psig and began my prep and warmup. When we were at the starting line at 10:30 Am the temperature was 65 degrees - PV=NRT or P=NRT/V. As the temperature rose, for the small volume of air the pressure rose and blew the tire off the rim. We were LUCKY it was at the start standing still.

Micheline Pro II 25 mm - We now using these tires and pump the tires when we start the ride.

Good luck with your riding and racing. YMMV

KRhea

We're a 300lb hard riding team that "looks" for climbs and loves to dive the corners and brake late and we ride either Conti 4000 25mm or Schwable Stelvios.
We've nothing but great luck with either tire, no blow outs or blow offs and no unusual wear. I run our tires at 120/125psi 90% of the time. If it's happens to be an unusually hot day I'll back off the pressure a bit.

I'm a very careful captain and really watch road hazards, pot holes etc and we get excellent mileage out of both tires. I'm running Stelvios on our newest build because I liked the "look" of the tires on the bike better than the Contis.

I have been running Pro 3s on my race bike and absolutely love that tire. One of the best I've ever ridden on a single. I'd be curious to know if anyone has tried them on a tandem. I also don't know if they're available in 25mm.
I did run the Conti 4000S Chili tire and it was OK just not as supple as the Pro 3.

Good luck on the "Bald" this weekend. We'll be attacking the climbs in the Columbia Gorge this weekend.

KRhea

mrfish

Pro Race 3 wasn't available in 25mm last week as they were introducing 23mm black then colours then grip, lite and 25mm versions. Doubles the novelty factor I suppose.

Hermes,

re. PV = NRT, the key thing is that T is measured on an absolute scale, i.e. degrees Kelvin with 0= -273 degC, so moving from a cold area to a hot area only marginally changes pressure in tyres, rather than doubling pressure as it seems at first glance.

45degF = 7 deg C = 280 deg K
65degF = 18 deg C = 291 deg K

So pressure change was (291-280)/280 = 3.9%, so not likely to have caused the problem. That said, something made the tyre blow off...

Hermes

Thanks for the calc. I knew the calculation was deg K and the convective change was a few percent. However, there is also the increase in pressure caused by radiant heating due to the sun and heat gain from the black pavement (we were in the mountains at 5000 feet elevation). Also, it had been on a fluid trainer for about 45 minutes while warming up. I do not know how to calculate or model all that.

It would seem logical to me that the pressure could increase from all the combined elements by 10% over two hours - 125 psig to 137.5 psig. I would have thought that the GP 4000 S 23 mm could take that but maybe not. As you point out, there was a failure mode that blew it off the rim. I will still be more careful about pumping up tires in the cold and racing on them after the sun rises and it gets warmer.

professorbob

Rotate them often

dvs cycles

Or run the back till it is worn out then put new one on front and move front to back.