Mountain Bike Reviews Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
50 Posts
Discussion Starter · #1 ·
I've been doing some experimenting and now have some questions. There is a hill on a paved road where I can coast for about .8 mile. I start at the same place and mark where I stop. I would try different things such as tire pressure and body position and sitting or attack position and each time I would be + or - 30 feet. My bike was a full rigid Cannondale with Python Airlights.
I got a new bike, a Specialized Stumpjumper with Resoloution tires, and do this same test. I get nowhere close. Probably 120 ft. short. I've tried everything I can think of. Front and rear locked out, change the tire pressures, different positions and nothing seems to help. The wheels seem to spin fine with no brake drag. The hill is surrounded with trees, so it's not like a wicked headwind or tailwind.
All I can come up with would be the rolling resistance of the tires. Now, I know that this probably is'nt the best test, but wouldn't it be some indication? These Resoloutions seem to make more noise when riding on pavment than the Pythons do. I don't spend much time on pavement, but I have to ride it some depending on what trails I choose. The two tires seem to hook equaly well in the dirt too.
Please give me your input.
Thanks,
Scott.
 

·
Team BikeWood
Joined
·
161 Posts
It's the tires...

The Pythons are a fast rolling XC race tire. The Specialized tires are much more of an all around tire. And from my own personal experience, every Specialized tire I've owned has a very high rolling resistance compared to other tires in their class. The data obtained from some of the German rolling resistance tests seems to reflect this too.
 

·
Team BikeWood
Joined
·
161 Posts
It's true there could be several factors contributing to what you're seeing (hubs, weight of bike, weight of wheels, etc.), I'd still bet that the tires are the major difference. If you want to be sure, throw some Pythons on the new bike and see what happens.
 

·
Registered
Joined
·
50 Posts
Discussion Starter · #5 ·
Thanks for the help.
Both bikes seem to be fairly close (drag from seals and bearings) on just spinning the wheels. The weight of the two are within about 1 lbs. From a physics standpoint, the weight wouldn't make any difference. I know these are two different bikes, but the only real difference is the tires. That's why I was asking about the rolling resistance.
Where can I find the test you are talking about?
Thanks again,
Scott.
 

·
Ride on
Joined
·
639 Posts
I'm sure the Python has less rolling resistance than the Resolution. It has smaller knobs and is made of harder rubber. That said, I would never spec a Python on my trailbike. My friend constantly complained about the lack of traction he got with his Python Airlights. I use a Resolution as my front tire and I am generally pleased with grip in a variety of conditions.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top