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How to Install a Bottom Bracket

The following information was derived from the Chris King Company instruction manuals

Spinning bike bottom bracket installation requires some specialized tools. To ensure proper installation, the use of high quality facing and thread chasing tooling is strongly recommended. Use an indoor cycling bottom bracket marked MTN (A) on 68 or 73mm bottom bracket shells with mountain-style cranks. Use a spinning bottom bracket marked ROAD (B) on 68mm bottom bracket shells with road-style cranks.

Preparation of Bottom Bracket Shell
Proper preparation of the bottom bracket shell on your indoor cycle is required for best bottom bracket performance, durability, and longevity. Chase the bottom bracket shell threads to ensure that threads are properly oriented on the spin bike. Face the bottom bracket shell to ensure that the ends are square and parallel to each other. Be sure to remove all indoor cycle frame paint from bottom bracket shell/bottom bracket cup interface. Using a small file, deburring tool or sand paper, carefully remove any sharp edges or burrs from the spinning bike's bottom bracket shell surfaces. Clean bottom bracket shell threads and surfaces to remove any chips, shavings, and/or cutting oil.

Installation of Bearing Cups
Note bottom bracket cup orientation on the indoor cycle marking on the bottom bracket threads before greasing threads, as the grease may obscure the mark. Apply a generous coating of waterproof grease to the threads on the bottom bracket cups on your spin bike, as well as on the bottom bracket shell threads on the indoor exercise bicycle frame. Follow crank arm manufacturer’s instructions to determine proper bottom bracket cup spacer orientation. Proper spacer configuration is essential for correct bearing preload, chain line and crank arm positioning. If using a 68mm bottom bracket shell with 0 or 1 2.5mm bottom bracket cup spacers, move center sleeve inner O-ring to inner groove on center sleeve. See exploded bottom bracket diagram for details.

Some indoor cycling crank set designs may require additional spindle spacers to be installed onto the crank arm spindle to achieve proper bottom bracket bearing preload. Three spindle spacers are included and are only required when dealing with undersized bottom bracket shells, oversized crank arm spindle lengths, and other spinning bike bottom bracket spacing inconsistencies. Make sure that the double O-ring side of the center sleeve is pressed into either bottom bracket cup, seating the inner O-ring on the inner edge of the bottom bracket cup. With proper bottom bracket spacers installed on bottom bracket cups, thread bottom bracket cups into the spinning bike frame using a compatible bottom bracket cup spline tool and torque to approximately 40Nm (30ft/lbs).

Indoor cycling bottom bracket cups are compatible with the following external bottom bracket cup spline tools: Chris King External bottom bracket Tool, Park™ bottom bracketT-9/bottom bracketT-19 and Shimano™ TLFC32/ TL-FC33.

Clean crank spindle and apply a thin layer of grease to indoor cycle's spindle surface.

Spindle should be insertable into exercise bike's bottom bracket using hand pressure. Use of a mallet or other excessive force may cause bearing to separate. Before passing spindle through second bottom bracket bearing, be sure spindle is properly aligned with the spinning bike's bottom bracket bearing spindle sleeve. Follow crank arm manufacturer’s installation instructions to properly install crank assembly and achieve optimal bottom bracket bearing preload. Readjustment of bearing preload may be necessary as the exercise bike's bearing breaks in. Check for play in bottom bracket/crank set assembly periodically and adjust as needed.

Indoor Cycling bottom bracket bearings are designed to provide the maximum life of any bottom bracket with a minimum of maintenance. Besides an occasional bearing preload adjustment, the only service necessary is an occasional cleaning and regreasing of the bearings. Exercise conditions and use will dictate how often to service your spinning bike's bottom bracket. In wet conditions, service may be necessary as often as every 3 months; in dry conditions, up to every 6 months.

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