Shimano UN55 Square Taper Bottom Bracket User Manual

1. Sarrera

This manual provides essential information for the proper installation, maintenance, and care of your Shimano UN55 Square Taper Bottom Bracket. The UN55 is designed for traditional square taper cranksets, offering reliable performance and durability for various cycling applications, including road and off-road use.

It features a sealed cartridge design for protection against dirt and moisture, ensuring smooth operation and extended lifespan. Please read this manual thoroughly before installation and use to ensure optimal performance and safety.

Shimano UN55 Bottom Bracket in packaging

Figure 1: Shimano UN55 Square Taper Bottom Bracket in its retail packaging.

2. Konfigurazioa eta instalazioa

Proper installation is crucial for the performance and longevity of your bottom bracket. If you are unsure about any step, it is recommended to consult a professional bicycle mechanic.

2.1 Beharrezko tresnak

Crank puller tool
Bottom bracket removal/installation tool (compatible with Shimano square taper)
Torque-giltza
Grease (e.g., bicycle-specific lithium grease or anti-seize compound)
Trapu garbiak

2.2 Instalazio-urratsak

Osagai zaharrak kendu: Use a crank puller to remove the crank arms. Then, use the appropriate bottom bracket tool to remove the old bottom bracket. Note the threading direction; the drive-side (right) cup often loosens clockwise on English/BSA threads.
Clean Bottom Bracket Shell: Thoroughly clean the bicycle frame's bottom bracket shell threads. Remove any old grease, dirt, or debris. Inspect the threads for damage.
Aplikatu koipea: Apply a thin, even layer of bicycle grease or anti-seize compound to the threads of the bottom bracket shell and the threads of the new Shimano UN55 bottom bracket. This prevents corrosion and facilitates future removal.
Install Drive-Side Cup: Insert the drive-side (right) of the UN55 bottom bracket into the frame. Begin threading by hand to ensure it starts straight and avoids cross-threading. For English/BSA threads, the drive-side cup tightens counter-clockwise.
Install Non-Drive-Side Cup: Once the drive-side is partially threaded, insert the non-drive-side (left) cup. Thread it in by hand. For English/BSA threads, the non-drive-side cup tightens clockwise.
Tighten Bottom Bracket: Use the bottom bracket tool and a torque wrench to tighten both sides to the manufacturer's specified torque (typically 50-70 Nm, refer to specific Shimano documentation if available). Ensure both cups are flush with the frame and securely tightened.
Biradera-besoak instalatu: Apply a thin layer of grease to the square taper spindle ends. Slide the crank arms onto the spindle, ensuring they are fully seated. Install the crank bolts and tighten them to the manufacturer's specified torque (typically 35-45 Nm).

Shimano UN55 Bottom Bracket with square taper spindle

Figure 2: The Shimano UN55 Bottom Bracket, showcasing its sealed cartridge design and square taper spindle.

3. Mantentzea

The Shimano UN55 bottom bracket features a sealed cartridge design, which minimizes the need for frequent maintenance. However, periodic checks are recommended to ensure optimal performance and extend its lifespan.

Ohiko ikuskapena: Periodically check for any play or looseness in the crank arms or bottom bracket. If play is detected, ensure crank bolts are tightened to specification. If play persists, the bottom bracket may need replacement.
Garbiketa: Keep the area around the bottom bracket shell clean from dirt and debris. While sealed, excessive buildup can still affect performance or lead to premature wear of external components.
Saihestu presio handiko garbiketa: Do not direct high-pressure water sprays directly at the bottom bracket area, as this can force water past the seals and contaminate the bearings.

Shimano UN55 Bottom Bracket showing the non-drive side cup

3. irudia: hurbileko planoa view of the Shimano UN55 Bottom Bracket, highlighting the non-drive side cup and sealed bearing unit.

4. Arazoak

Ohiko arazoak eta irtenbideak
Sintoma	Kausa posiblea	Irtenbidea
Creaking or clicking noise from bottom bracket area	Loose bottom bracket cups Dry threads on bottom bracket or crank bolts Worn bottom bracket bearings Loose chainring bolts	Check and re-torque bottom bracket cups. Remove, clean, grease, and re-install bottom bracket. Replace bottom bracket if bearings are worn. Check and tighten chainring bolts.
Play or wobble in crank arms	Loose crank arm bolts Worn bottom bracket spindle or bearings	Check and re-torque crank arm bolts. Replace bottom bracket if spindle or bearings are worn.
Stiff or rough pedaling	Contaminated or worn bottom bracket bearings Over-tightened bottom bracket	Replace bottom bracket. Ensure bottom bracket is torqued to specification, not over-tightened.

5. Zehaztapenak

Ezaugarri	Xehetasuna
Ereduaren izena	BB-UN55
Marka	SHIMANO
Errodamendu mota	Kartutxo itxia
Buru Mota	Square Taper (JIS)
Maskorraren Zabalera	68 mm
Buruaren Luzera	110 mm (as per product description, other lengths available)
Materiala	Aluminum (body), Steel (spindle)
Pisua	Approximately 0.1 Kilograms (100g)
Lubrifikatzaile bateragarria	Grease (for threads and spindle interface)

6. Bermea eta laguntza

For warranty information and detailed product support, please refer to the official Shimano website or contact your local Shimano dealer. Keep your proof of purchase for any warranty claims.

Official Shimano Webgunea: bike.shimano.com

For technical assistance or questions regarding installation and maintenance, it is recommended to consult a certified bicycle mechanic.

SHIMANO BB-UN55