Lew PRO VT-1 Wheel Hub and Bearing Maintenance Guide
Support photos at bottom of page

Tools/Additives:
• No tools required for adjustment and assembly. We encourage the use of vernier calipers and/or a gap measuring device.
• No adhesives needed for holding the bearings in place thanks to the high precision of the bearing seats which are very consistent for a hand press fit. The bearing seats are molded on high precision ground tooling at a precisely controlled temperature.

Technical data:
• Front axle length = 3.64 inches / 92.456 mm
• Rear axle length = 4.74 inches / 120.396 mm

Assembly instructions:
1.) Take care to handle the cut ends of the boron axle. Small boron fibers can be very painful if pushed into the skin of the fingers. Light gloves and eye protection are recommended to ensure safety. Boron fiber/ boron dust is not harmful to a degree exceeding wood dust or fiber.

2.) The axle should not move end-to-end when loaded in the direction of the axle tube.

3.) If the axle moves end-to-end and the bearings do not move, then the over-axle spacer between the axle end and the bearing inner race is insufficient in length. Increasing the length of the over axle-spacer will eliminate the movement (a 0.015" / 0.3810mm steel shim is an acceptable and common solution).

4.) If the over-axle spacer inside the hub is not firmly captured between the inner bearing race it may move (rattle). If the over-axle spacer inside the hub has movement in the direction of the axle tube increasing the length of the over axle-spacer will eliminate the movement (a 0.015" / 0.3810mm steel shim is an acceptable and common solution).

5.) The end caps should not contact the cut end of the axle. The load should transmit from the end-cap to the over-axle spacer to the bearing, through the internal hub over-axle spacer, through the opposing bearing/ bearings, through the over-axle spacer and into the other end-cap. The end caps have an internal depth of 0.280" / 7.1120mm. The exposed amount of axle protruding beyond the over-axle spacer is to be between 0.260" / 6.6040mm and 0.270" / 6.858mm. The 0.010" / 0.2540mm gap is required to ensure the load path is directed through the ID bearing race and series of spacers. This is the reason the effective cut-off of the Lew Pro VT-1 axle is not required to be straight nor parallel. While it is good manufacturing practice to cut the ends parallel (from a cosmetic consideration), there is no effect if the cut is slightly off of square.

6.) The reason we recommend the USE SpinStix quick release is because they offer an increasing compression force as the quick release is closed. Unlike a ‘cam style’ quick release the SpinStix does not "drop" pressure in the final "closed" position. A very small amount of movement back-and-forth in the direction of the axle may be available using a cam style quick release which generates the highest pressure prior to the fully-closed position. This drop in pressure will relax the compression in the series of over-axle spacers and bearings and the bearing wear will accelerate. It is like a crack in the dam... first a trickle, then a stream, then the dam breaks.

7.) We emphasize the necessity of the SpinStix style quick release, but unfortunately most cyclists do not understand the technical reason why ‘cam style” must not be used.  Most people assume that cam style should not be used because the axle is not strong or stiff enough to resist the compression. That is not true: in a properly assembled Pro VT-1 system the axle does not receive any compression load from the quick release. The load the axle receives is from bending moment (force and acceleration), not compression.

8.) If the bearings shift when loading the axle along the length of the axle tube, then the over-axle spacer inside the hub is too long and the bearings do not fully "seat" in the hub. Shortening the over-axle spacer inside the hub will eliminate the movement.

9.) If the bearings "bind" with compression from the quick release this does not mean the axle is compressing or flexing (significant pressure cannot be generated from the quick release to compress the axle-- the axle is too strong and stiff), it only means that the over-axle spacer inside the hub is too short and the ID bearing race is forced out the plane of the bearing, side-loaded and drag increases. This situation must be corrected to avoid rapid aging or failure of the bearing. The bearings are not needle or thrust type designs and they do not take side loads unless they are connected through the series of over-axle spacers which physically links them into a "double" row of balls. It is only in a "linked" configuration that the wheels can properly accept an axial (in the direction of the axle tube) load. This is also the required condition not only of the front hub and rear hub, but also the cassette body. The cassette body must also be linked with an internal over-axle spacer to create a "double-row" of ball bearings.

10.) The amount of space between the cassette bearing and the hub bearing on the cassette side should be the smallest space possible. Too much space will diminish the engagement of the pawls into the outer ratchet leading to accelerated aging. If the clearance is too small the cassette will mechanically drag on the wheel hub and excessive mechanical friction will accelerate aging. The system is typical adjusted by placing the cassette body onto the rear wheel hub without the springs or pawls and only one 0.015" / 0.3810mm thrust washer. In this manner, the drag can be determined without any contribution from the transmission. If any metal-to-metal drag is present a second thrust washer may be added. A third or fourth thrust washer may be used if needed to eliminate any metal-to-metal interference. When smooth turning is achieved no more thrust washers should be added. The minimum number of thrust washers to achieve smooth turning should be used. Adding additional thrust washers beyond the minimum number required will minimize the performance of the system: less is not better and more is not better. The proper quantity the number required for smooth turning and no more.

11.) Once the cassette-hub spacing is properly adjusted, load the springs and pawls into the cassette and assemble the system.

12.) Ensure the springs are placed into the cassette with the open end of the spring hook oriented toward the OD of the wheel. It is possible to insert the springs with the open hook end facing toward the center of the wheel. Proper spring rate will not be possible with the springs improperly inserted and adversely alter the simultaneous engagement of the pawls. The result may be accelerated aging.

CASSETTE BODY MARKING FROM THE PAWLS
Uli Fahl / TUNE emphasized to us the requirement for concentric precision of the hub and cassette.
• Concentricity of the cassette and wheel hub is very high. The aluminum bearing location in the hub was first turned and then taper guided until the final ream size.
• It is suspected the heat-treated hardened pawl to over-power the anodizing.
• The pawls must move within the slot in the direction of the slot (in the direction of the axle) for this wear to occur.

* The Green Color End Cap is only for the photographic purpose of differentiating front end cap from rear Shimano SRAM End Cap because they are identical height.