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Old August 3rd 03, 06:56 AM
Dan Daniel
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Default Q. Will I benefit from different tire size or type?

On 2 Aug 2003 19:19:02 -0700, (Joe Samangitak)
wrote:

I have 700 x 35 tires on my hybrid bike, and I've recently learned
that I can change the 35 (width?) to a different size, ie. 32, 28 etc.
Question is, do I want to? I ride exclusively on pavement in a city,
so I'd like to maximize tire efficiency for this type of driving.

- First of all, will it work to put different width tires on my
hybrid/city bike, or is there an issue with narrower widths coming off
the rim, etc.?


Yes, you can put thinner width tires on.

- Secondly, is there an advantage to using a different tire size if I
can, or should I assume the original 700 x 35 tire size was already
designed ideally for city driving?

The 35mm was chosen for its aesthetic appeal to the target market for
the bicycle. I'd imagine that most hybrid buyers will put more value
on comfort and the feeling of safety a bigger tire gives than on speed
and efficiency.

There are advantages and disadvantages to narrower tires.

Since they are smaller and often have less rubber than wider tires,
they weigh less and are easier to accelerate. My city riding has a lot
of stops and slowdowns, so it makes a difference for me.

A smaller contact patch means less friction, so they are faster, but
my gut says that this is actually a relatively small difference.

Higher pressure, so less time and energy spent over bumps, etc..
moving the tire itself rather than the whole bike.

Higher pressure and thinner rubber can mean more flats. And more road
bumps transmitted into your body rather than absorbed by the tire.

Road cracks and potholes become much more important. Something that I
can ignore on wide tires can catch a skinny tire and send me down if I
don't pay attention.

For me, different tires and bikes lead to different riding experiences
in a city. A narrow tire requires more attention to the road, I seem
to go faster and so have to pay more attention to traffic, and going
faster can be both stressful and fun. A fatter tire lets me be more
relaxed about the road condition, is less jarring, and lets me jump
curbs and do other things that I wouldn't try on narrow tires.

That's the trade-off I see- speed, precision, and the need to maintain
focus on the road versus comfort, slop, and the ability to not be too
concerned with the road. Each of us finds our own balance point.

I would suggest finding a 28mm tire that is lighter than your present
one and trying it out. Maybe your bike shop has a bike similar to
yours with tires this size, and you can run it around the block to see
how it feels?

Don't forget how important tire pressure is, also. The same tire can
take on very different characteristics at different pressures. I have
some Continental Travel Contacts on a mountain bike, which are 1.75
inches wide. I can use than at 45 lbs or at 80 lbs, and it is close to
changing tires when I change the pressure. If you are running your
present tires at the lower end of their pressure range, go to the top
end to get a taste of some of the changes skinnier tires will make.
Even five or ten pounds can make a huge difference in how a tire
rides.

- Lastly, I read expert testimonials that said slick tires are best
for pavement riding, cornering, wet driving, traction and have less
rolling resistance, basically because more rubber contacts the road. I
was looking to buy the Michelin Transworld City, but its not a pure
bald slick, it has fairly deep recesses, presumably to siphon off
water (which I read isn't necessary for bike tires, and that this
system doesn't work better than slicks). So my question is, would I be
better off driving in my city with a pure bald slick, such as the
Avocet Road 20, instead of the Michelin Transworld City? Or is it even
better to use DIFFERENT TIRES for the front and back? Any commonly
known disadvantages to going with pure bald untreaded slicks on
pavement, such as premature tire wear, as compared against tires with
a tread?


20mm tires in a city seems extreme. I ride 23mm on one bike and I
think that the next set will be 25mm. 23 just requires more attention
and care than I feel like giving all the time. Then again, I've ridden
23mms in a city for years and keep buying them. 32mm on another bike
was just a bit too heavy and wide for my needs and taste.

Tire life depends on the thickness and quality of the rubber. Tread
per se has nothing to do with it. No tread pattern or a minimal
siping is what I look for. About all you gain from heavy treads is a
funny road buzz and energy going into moving the tire knobs around
rather than moving you forward. But as someone already said, marketing
drives a lot of the tire design issues, so I wouldn't let minimal
treads stop you from buying a tire outright. City riding is not about
the absolute highest level of efficiency. What is very critical to a
racer is one small factor among many for non-competetive city riding.
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