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Rolling resistance
On a ride recently i noticed my bike didn't really wanna roll all that well at speed, when i say speed i say 45-55km/h. My mate on his merida dualy could pretty much come past me rolling 10km/h faster. We were both on 2.1 knoblies with similar setups besides hes being a bit lighter. Could a change of hubs from deore to xt make a difference.
Besides tyres what could make a difference?
Thanks
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The way I see it, Tyres, Pressure, hubs, brake discs rubbing, aerodynamics and the weight of the wheels all play a part in how fast you roll/move without pedalling.
The higher the pressure the better, but finding the happy medium between traction, weight handling and rolling resistance is the key.
Hubs vary a fair bit, the better the quality of hub the less friction is has when rolling. They use better seals, better bearings and lighter.
Make sure your discs don't rub on your pads. If they are warped, straighten them out.
Aerodynamics are huge. The more frontal area you push, the more resistance you have. Tucking down as low as you can and tucking your chicken wings in, make a massive difference.
There's probably a lot more technical answers out there, but that's my take on it.
Well at those speeds hubs make bugger all difference, along with most other things. Your biggest enemy once the speed gets up is wind or more accurately front on resistance caused by your body primarily (wind).
Just think about a time trial on a road bike at those same speeds, Your number one aim is to be as aerodynamic as possible.
To do this on a MTB you need to get your head very low like almost on the bars arms and hands tucked in and in line with your body. Your aim is to reduce the amount of your body exposed to the air/wind from front on.
Is your mate tucked up into a crouch position when he goes past you?
Give it a try and see what difference it makes.
At that speed the aero drag makes a massive difference, if you tuck down then sit up you will feel the deceleration.
I have found switching tyres makes a massive difference as well. When I swapped from 2.1 corssmarks to 2.25 ardents on me trail bike it slowed me down a lot in the down hill road sections to and from the trails.
funnily enough my head was at the same height as my bars, arms fully down, So minimal wind resistance.
I actually completely forgot about tyre pressures thou. I was running probs around 30 psi
so thats most likely the problem.
there. I normally run my tubeless tyres at about 30psi because I'm a gumby and like (need) all the grip I can get, but over the weekend while topping up the Stan's goop in preparation in preparation for next weekend's trip to Parkes, I left them at whatever the compressor blew them up to when remounting the tyres - a lot higher than 30.
Took it for a spin and was impressed by how easy it was to pedal. Thinking hmm....
might have to try the rear at least with a bit more air in it.
How hard was your mate pedalling before he went into freewheel and sailed past you?
Is your mate stronger than you?
Were you both riding on the same surface?
How steep was the hill you were coming down and where on it did he pass you?
I doubt the bikes would have made any difference. Eliminate the differences in the people before the bikes - same as trying to lose 200 gms off your bike when you're 5kg's overweight...