How much does hub affect speed?
12-12-16 | 11:04 PM
#26
Insane Bicycle Mechanic
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Dude, if you're riding knobbys at 15 to 25 mph on flat ground, you're an ultrastud and obviously training too much.
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12-12-16 | 11:42 PM
#28
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
One accurate measurement is worth a thousand expert opinions - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
12-13-16 | 09:56 AM
#29
Keepin it Wheel
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That's just crazy. Those road 'pros' must not have been any good. I wish they had said exactly what tyres he had, they must have been pretty small/tight knobs for hardpack.
12-13-16 | 08:14 PM
#30
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12-13-16 | 11:33 PM
#31
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From: Elevation 666m Edmonton Canada
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WRONG. The hub that has the extra drag probably has DAMAGE, and/or has been improperly adjusted. The ONLY thing, other than bearing condition/adjustment/grease, that might cause higher drag would be any rubber seals on the hub.
as to MOMENTUM... the rim and tire/tube weight lends momentum to the wheel when spun in-frame... I always test for bearing tension with the wheel OUT of the frame, and tire/tube removed... i lay the axle on two open fingers after spinning it up... if the axle wants to turn on my open fingers, it gets readjusted or rebuilt as needed.
"slightly tight"... this will cause heat buildup during use... the product of heat is increased friction... the heating can, and DOES, cause melting of the cones' hardened surface! Ever taken a close look at the "worn" cones with pitting going on? yep, MELTED surfaces. Heat and pressure causes GALLING of the surface. Rust can also promote galling... once again, the extra friction from the rust pitted surface causes heat to build up... add pressure, more heat gets produced, expansion of parts involved further increases heating... whalla! time to replace cones and balls....
A properly adjusted set of hubs does in fact effect your "speed", since a dragging hub bearing set WILL slow acceleration, and yes, TOP SPEED. a bit of fresh, light grease, and proper adjustment makes for a happy, FASTER, rider. Rotating mass also plays into enjoyment... Note all those fancy bikes with carbon fiber and aluminum bits all over the place on them... there are good reasons for those pieces!
Grease... too heavy of grease viscosity will cause issues, too... "FLOWBACK" is needed to keep grease on the bearing surfaces... friction sets in... heat builds... guess the rest... i use a bicycle specific grease... it is light enough to allow flowback, without getting too thin during use.
Reduce any ROTATING MASS to improve acceleration... and get those bearings right, if you have the tools and skills needed.
as to MOMENTUM... the rim and tire/tube weight lends momentum to the wheel when spun in-frame... I always test for bearing tension with the wheel OUT of the frame, and tire/tube removed... i lay the axle on two open fingers after spinning it up... if the axle wants to turn on my open fingers, it gets readjusted or rebuilt as needed.
"slightly tight"... this will cause heat buildup during use... the product of heat is increased friction... the heating can, and DOES, cause melting of the cones' hardened surface! Ever taken a close look at the "worn" cones with pitting going on? yep, MELTED surfaces. Heat and pressure causes GALLING of the surface. Rust can also promote galling... once again, the extra friction from the rust pitted surface causes heat to build up... add pressure, more heat gets produced, expansion of parts involved further increases heating... whalla! time to replace cones and balls....
A properly adjusted set of hubs does in fact effect your "speed", since a dragging hub bearing set WILL slow acceleration, and yes, TOP SPEED. a bit of fresh, light grease, and proper adjustment makes for a happy, FASTER, rider. Rotating mass also plays into enjoyment... Note all those fancy bikes with carbon fiber and aluminum bits all over the place on them... there are good reasons for those pieces!
Grease... too heavy of grease viscosity will cause issues, too... "FLOWBACK" is needed to keep grease on the bearing surfaces... friction sets in... heat builds... guess the rest... i use a bicycle specific grease... it is light enough to allow flowback, without getting too thin during use.
Reduce any ROTATING MASS to improve acceleration... and get those bearings right, if you have the tools and skills needed.
I could always feel the drag, especially with my new derailler bikes. Mine were more often a bit loose I think.
A different story , but my SA 5w spins 2 or 3 minutes and my Rohloff, with 4 bearings, about 20 seconds.
Top speeds on same bike and same tires ... SA 45.8, Rohloff 42.1 on same hill. I can feel the slightest slope with the SA5, it's a heavy bike of course. No way I would bet on the racer with a bit tight hub.
12-14-16 | 12:04 AM
#32
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So yes, bad hubs can cause exactly the behavior the OP described, and the difference can be significant.
One word of caution though. Angular momentum of the rim plays a huge part in how long a rim takes to spin down. A heavier rim will spin longer than a lighter rim, with the same hubs. This can be hugely misleading when comparing too different wheelsets, for example.
12-14-16 | 06:46 AM
#33
Passista
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This comes up so often it deserves a sticky.
The differences in drag related to how long a wheel spins off the bike are miniscule. They have about as close to zero as possible effect on the drag or speed of a bike.
It's a simple question of inertia, compare the mass of the wheel to the 200# bike and rider as a unit.
The differences in drag related to how long a wheel spins off the bike are miniscule. They have about as close to zero as possible effect on the drag or speed of a bike.
It's a simple question of inertia, compare the mass of the wheel to the 200# bike and rider as a unit.
12-14-16 | 09:34 AM
#34
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Joined: Apr 2007
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From: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Previous bikes:Motobecane Mirage, 1972 Moto Grand Jubilee (my fave), Jackson Rake 16, 1983 C'dale ST500.
Secondly, the OP's question was whether one hub was better and faster than another, with no mention of a bad hub. With no other info to go by the answer is no. Both I and others have noted that there are exceptions.
There would be no point in addressing the question of whether a damaged or maladjusted hub could have a negative effect.
As for angular momentum, what you say is true, but there's little point in doing such a comparative test in the first place.
Last edited by cny-bikeman; 12-14-16 at 10:00 AM.
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