What's the difference? Shimano Hollowtech 2 and BB comparison summary and points to consider when choosing

Posted at: Nov. 28, 2021

In-depth comparison of Shimano Hollowtech 2 and BB (bottom bracket) units! A comparison of the specs of the different BBs in terms of weight and compatibility. The following is a summary of the points to consider when selecting a BB.

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Hollowtech 2 BB lineup

For road bikes

Hollowtech 2 BBs for road bikes are available in three types of screw-in type and two types of press-fit type in the current model lineup.

The BB of DURA-ACE, the top grade for road bikes, is BB-R9100, and it uses small bearings. Although it is a top grade part, some user reviews complain about the reluctance of rotation and durability.

The SM-BB72-41 is a press-fit BB for ULTEGRA/105 grade road bikes, but it cannot be used with threaded BB shells.

The ULTEGRA 105 grade threaded BB for road bikes is the SM-BBR60, which is a popular and standard BB because of its high quality and only 8g difference in weight compared to the higher grade BB-R9100. adaptor (TL-FC25) is required because of the different diameter.

BB-RS500 is a TIAGRA grade screw-in BB for road bikes, which is often installed on 105 and TIAGRA grade complete bikes, and is an entry-level Hollowtech 2 BB. Slightly heavier than higher grade BBs.

BB-RS500B=PB, a GRX grade press-fit BB for gravel roads, slightly heavier than the higher grade SM-BB72-41, but more durable thanks to a new sealing structure.

For MTB

The Hollowtech 2 BB for MTB is available in three screw-in types in the current model lineup. There are no press-fit BBs.

The SM-BB93 is the top grade XTR screw-in BB for MTB, weighing only 73 grams and compatible with not only 73mm but also 68mm, so it can be installed on road bike frames.

The gold-colored SAINT SM-BB80 threaded BB for MTB is slightly heavier at 95g, and is compatible not only with 73mm but also with 68mm and 83mm.

BB-MT800, DEORE XT’s screw-in BB for MTB. 82g heavier than the top-of-the-line SM-BB93, but other than that, there is not much difference in specifications.

Comparison of Shimano Hollowtech 2 and BB

Here is a comparison of the Shimano Hollowtech 2 BBs introduced so far in terms of grade, weight, system, and compatible shell width.

Threaded BB

Products Grades Weights Formulas Supported Shell Widths
BB-R9100 DURA-ACE 65g Threaded 68mm、70mm
SM-BBR60 ULTEGRA/105 77g Threaded 68mm、70mm
BB-RS500 TIAGRA 92g Threaded 68mm、70mm
SM-BB93 XTR 73g Threaded 68mm、73mm
SM-BB80 SAINT 95g Threaded 68mm、73mm、83mm
BB-MT800 DEORE XT 95g Threaded 68mm、73mm
SM-BB52 - - Threaded 68mm、73mm

In terms of weight, it does not make much difference which grade you choose, as it is light enough to be under the 70g range.

On the other hand, shell widths are available in a variety of widths, so there is a good chance that one of the models will fit your frame.

Press-fit BB

Products Grades Weights Formulas Supported Shell Widths
SM-BB72-41 ULTEGRA/105 69g Press-fit 86.5mm
BB-RS500-PB GRX 70.4g Press-fit 86.5mm

There are only two options for press-fit BBs in the current models, and both have almost identical specs. The GRX, which is a gravel component, is built for dirt, so you can choose the BB-RS500-PB for gravel or the SM-BB72-41 for road.

Points to consider when selecting the Shimano Hollowtech 2 BB

First, let’s narrow it down by “mounting standard.

Shimano Hollowtech 2 BBs are divided into two types: screw-in and press-fit. There are many screw-in BBs available, but there are only two press-fit BBs available from the current model lineup.

Next, you can narrow down your selection by the width of the BB shell. Shimano Hollowtech 2 BBs are available in five different widths: 68mm, 70mm, 73mm, 83mm, and 86.5mm, so choose the one that matches the width of your frame.

At this point, your choices will be quite limited.

Weight, Color, and Grade are the Final Deciding Factors

Once you’ve narrowed down your search by “mounting standard,” the last thing to consider is weight, color, and grade.

Most of the Shimano Hollowtech 2 BBs are lightweight models to begin with, so there is not much of a weight difference.

Also, Shimano Hollowtech 2 BBs are not available in many colors, so you can choose the color you want to match your frame.

Lastly, the grade of Shimano Hollowtech 2 BBs is generally said that there is not much difference in performance between the different grades.

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