Friday 20 May 2011

New tyres - Continental SportContact

Continental's Grand Prix tyres are
fast, but don't like high speed
cornering and braking.
For a few months now I've been riding with Continental Grand Prix tyres on the front of my Mango. They're lovely lightweight and fast tyres, but unfortunately I have to say that they've not really worked out, at least on this bike. I used my pair briefly last year before removing them for winter, and re-fitted them only about a month ago. They've been used for about 800 km, which is not all that impressive.

The main problem, I think, is that they are simply not intended for use on a fast tricycle like the Mango. Sideways forces, especially when braking, are too much for them. On a two-wheeler it isn't possible to put such a sideways force on a tyre, nor to brake with a considerable sideways force on the front wheels without instantly falling off. The rubber was lost right outside our home, as I rode in quickly. A touch on the brakes, the wheel on the inside of the turn was in a skid, and there was a smell of rubber.

Even if I'd not had this problem, I was already planning to replace the tyres. Both Grand-Prix tyres already had cuts in them presumely due to small stones or pieces of glass (I didn't find the cause). This all happened a bit too soon for a practical tyre.

I'm now trying their SportContact
tyres instead. Hopefully these will
stand up better to everyday use.
I've not given up on Continental, but have replaced the Grand-Prix with the Continental SportContact. These are the same size, 28-406, but they are designed for everyday use. They weigh a bit more, have a bit more rubber, have the "SafetySystem" anti-puncture protection, sidewall reflectors, and a lower cost. they're also still supposed to be fast. It sounds like a promising combination, so I'll see how I get on with them over the next few months.

The advertised weight for the SportContact in this size is 295 g, however mine were actually a little lighter at about 270 and 280 g each.

New tyres fitted and ready to go, on a cycle path wide
enough that riding an unusual bike is never a problem.
One very nice thing about both the SportContact and the Grand-Prix is that both are easily mounted on and removed from the rim without tools, and both sit well on the rim and run true straight away. This can be quite difficult to achieve with some tyres.

The maximum pressure stated on the side-wall on the SportContact is 6 bar ( 85 psi ), but the accompanying paperwork attached to the tyre says 7 bar ( 102 psi ). I'm using the higher pressure. I have suspension so don't need the tyres to contribute too much to comfort, and they'll roll faster at the higher pressure.

My rear tyre remains a Schwalbe Marathon Racer. This still barely looks run-in. Actually, it wouldn't have been a bad choice for the front wheels as well.

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dr2chase said...

I find myself wondering (as I design a yet-again-improved dynamo-driven electrical system, this one perhaps good enough to build) how long it will be before someone deploys reliable ABS for bicycles. There is one described in Bicycling Science, tested to fork destruction even, but somehow it has never seen the light of day.

Jon Bendtsen said...

Why would you not run Marathon racers in the front?

DrMekon said...

I have marathon racers on my bike - the front has done over 10000km with no punctures, and the rear did 7000km with only 2 punctures. For a relatively light tyre, I am really impressed.

Slow Factory said...

@dr 2: There is already ABS on bikes: To discover it, get in a car with ABS and go down a steep hill. Now cut the engine and pull out the fuses on the brake assist circuit...

OK, sorry, just kidding of course, the problem with ABS on bikes is more philosophical than technical. A bike is simple. ABS is not.

@David: Maybe if you still have problems with these Contis you can see if they will develop a special "David Hembrow Edition" tyre that will match your needs :-)

Anonymous said...

I've been using Conti Travel Contact on Bristol's streets for some years, with virtually no punctures and good longevity. The side-wall reflectors are great too, try taking a flash photo of your tyres in the dark and you'll see what I mean. Recommended.

kfg said...

". . .ABS for bicycles. . . it has never seen the light of day."

Perhaps because it is a solution looking for a problem.

Might make some sense in a pedal by wire system (of questionable sense in and of itself), but you'd still want purely mechanical backup.

Dr C. said...

The paraboloid-esque profile of bicycle tyres isn't really ideal fortri/quad/etc cycle applications where the cycle does not lean to at all/to the same degree. What would be a good idea is if a company made square profile (car-like) tyres designed for tri/quad/etc cycles

Slow Factory said...

Yes! The Square, a.k.a. as "The Hembrow"! ;-)

David Hembrow said...

Actually, there have been attempts at making square section tyres for velomobiles. Vredestein made one, but then everyone decided they didn't like it much so it didn't sell well (it's not a bad tyre at all, just not an exciting one - neither especially fast nor especially durable). Schwalbe are supposed to be producing something special about now. I've not seen the result yet.

David Hembrow said...

Oh, and as for why not Marathon Racers on the front ? Actually, that's a very good question. Perhaps the best answer is "just because". I felt I would like to try something which is potentially a little sportier. However, if the sensible me gets in charge then I'll probably end up with Marathon Racers all around, as they're a very fine choice.

kfg said...

"square profile (car-like) tyres"

These are actually made. However, they are necessarily heavy (try to make a square balloon and you'll quickly see why), have high rolling resistance and require camber neutral suspension systems to actually derive any particular benefit from them (even at fairly low cornering forces the carcass deforms enough to "peel" the tread from the surface). They also introduce the possibility of hydroplaning.

And there's really no problem with round profile tires on HPVs that can't be addressed with carcass construction and rubber compound.

Ron said...

Are they good on a rainy road?

David Hembrow said...

I've only had damp roads so far, and have not ridden them in pouring down rain. Also, we're kept away from the worst of conditions here. However, no problem so far.

I do know what it can be like. The Tioga Comp Pool and Avocet Fasgrip Carbon 12 tyres are my reference for dreadful behaviour in the wet. Both of these are lethal on any damp surface.