Glenn1234
05-20-09, 09:28 PM
How do you tell if a wheel hub is straight or not?
Bicycle Mechanics - Hub Straightness
Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.View Full Version : Hub Straightness
Panthers007
05-20-09, 10:29 PM
As in it spins true? Remove the axle and roll it on an even surface - such as a glass table-top.
Glenn1234
05-20-09, 10:41 PM
As in it spins true? Remove the axle and roll it on an even surface - such as a glass table-top.
As in whether the wheel will spin true if all else (the axle, the bearings and so on is good). The part in the middle of the wheel that the spokes hook to.
As in whether the wheel will spin true if all else (the axle, the bearings and so on is good). The part in the middle of the wheel that the spokes hook to.
Panthers007
05-20-09, 11:33 PM
Those are called 'hubs' and the holes for the spokes - eyelets.
Through the center of the hub you will find the axle-spindle, unless someone removed it. To get to the axle-spindle you would need to disassemble the hub, as if for an overhaul. There is a large amount of space dedicated to how-to a hubset,
Through the center of the hub you will find the axle-spindle, unless someone removed it. To get to the axle-spindle you would need to disassemble the hub, as if for an overhaul. There is a large amount of space dedicated to how-to a hubset,
Glenn1234
05-20-09, 11:41 PM
Okay it seems we're talking past one another. I'm not asking about how to tell whether the axle is straight. I'm asking about how to tell whether the hub itself is straight.
mrrabbit
05-21-09, 12:04 AM
There are three types of hub straightness...
A. Body Straightness
B. Machining Straightness
C. Cup Straightness [Extremely Important!!!]
A1. This assumes same size flanges on each side. Roll hub on flanges on chalk, etc. If perfectly parallel lines are created - no flaring out or in. STRAIGHT
A2. This assumes unequal flange sizes. Place hub in truing stand. Bring truing guides all the way up and bring points to within 1/8" of the flanges one at a time. Rotate hub. If flanges rotate perfectly - or both deviate a tad at the same time... STRAIGHT
B1. This test doesn't mean the hub is bad. Place hub in truing stand. Rotate. Does one side or both sides rise and fall during rotation. About 90% of all freewheel hubs will do this...about 10-20% of freehub equipped hubs will do this. If present, even when extreme, it has very little impact on shifting or chain drop - despite common myth.
C1. Adjust hub so that it has a slight grind. Turn hub several times. Does it bind in 2 or 4 places consistently? If yes...
- Unlock cones.
- Hold hub vertical.
- Remove top cone...clean grease around the outer 2-3 mm's of the edge of the body so you can clearing see the entire circumference of the cup edge.
- Turn the hub...does the cup turn flat...or does the cup noticeably rise and fall at certain points in excess of a couple millimeters?
- Put cone back in.
- Turn hub over...repeat the above.
If a cup rise and falls more than 2mm during rotation...
- Higher end hubs such as old Campy SR's and NR's can be salvaged with a press in a machine shop.
- El Cheapo generics...toss 'em. Don't even try to save 'em...don't even try to use 'em. They will grind out prematurely in the binding locations...for every 10 I import from Taiwan...I have to toss out on average 1 hub shell. (One way to build a supply of spare axles, cones and bearings...)
=8-)
A. Body Straightness
B. Machining Straightness
C. Cup Straightness [Extremely Important!!!]
A1. This assumes same size flanges on each side. Roll hub on flanges on chalk, etc. If perfectly parallel lines are created - no flaring out or in. STRAIGHT
A2. This assumes unequal flange sizes. Place hub in truing stand. Bring truing guides all the way up and bring points to within 1/8" of the flanges one at a time. Rotate hub. If flanges rotate perfectly - or both deviate a tad at the same time... STRAIGHT
B1. This test doesn't mean the hub is bad. Place hub in truing stand. Rotate. Does one side or both sides rise and fall during rotation. About 90% of all freewheel hubs will do this...about 10-20% of freehub equipped hubs will do this. If present, even when extreme, it has very little impact on shifting or chain drop - despite common myth.
C1. Adjust hub so that it has a slight grind. Turn hub several times. Does it bind in 2 or 4 places consistently? If yes...
- Unlock cones.
- Hold hub vertical.
- Remove top cone...clean grease around the outer 2-3 mm's of the edge of the body so you can clearing see the entire circumference of the cup edge.
- Turn the hub...does the cup turn flat...or does the cup noticeably rise and fall at certain points in excess of a couple millimeters?
- Put cone back in.
- Turn hub over...repeat the above.
If a cup rise and falls more than 2mm during rotation...
- Higher end hubs such as old Campy SR's and NR's can be salvaged with a press in a machine shop.
- El Cheapo generics...toss 'em. Don't even try to save 'em...don't even try to use 'em. They will grind out prematurely in the binding locations...for every 10 I import from Taiwan...I have to toss out on average 1 hub shell. (One way to build a supply of spare axles, cones and bearings...)
=8-)