SHIMANO BB-RS500 BSA-Innenlager (Lagerschalen) // Tiagra, Sora

Product Information

The design comes about as a solution to the well documented creaking issues associated with oversized press-fit systems. While these issues are near always the result of poor tolerances, the T47 standard promises to fix the creaking issue without sacrificing the benefits of an oversized interface. Pros: Stiffer than BB/PF30, in theory, without impacting other attributes; good crank compatibility, cheaper to manufacture than threaded or BB30 Cranksets with 24 mm spindle diameter are not all the same! SRAM and some other manufacturers make spindles that are 24 mm wide at one end, and 22 mm wide on the other, so the correct matching BB needs to be acquired.

In concept, at least, all of the standards we’ve covered are functionally sound. But the realities of relaxing tolerances can create other issues. Pros: Lighter than conventional setups but retains compatibility with ‘legacy’ cranksets; creates a wider BB shell without affecting crank width So it’s mostly eyeballing and trial and error. Some very rough guide (what I often try with first) would be:Threadfit 82.5 is not really a new standard in that it is compatible with BB86 cranksets and bearings. Crank designs that will fit: Standard 24mm external-type only. A GXP conversion kit is also available With the PressFit 30, they’re using the same technology with the larger bearings and the same technology with the bearings living inside the frame, but they’re utilizing the nylon to their advantage where you have a more realistic tolerance.” Cons: Can’t use cup-mounted chain guides; shell is wider but still small in diameter; requires a separate bearing puller and press for service, bearing bores can wear out and loose tolerances

This system is not without its issues however, with shells becoming oversized (due to wear) being a relatively common problem (leading Trek to release the very slightly oversized V2 bearings to compensate). 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. Technically only the R9100 is considered 'Dura-Ace', the others are 'non-series'. In any case they are all interchangeable - you can use BB-RS500 with an R9100 crankset. From what I've seen with balls you have the issue of ball material Vs race material (probably best if they are both the same - stainless is probably not an advantage), then ball size, then lubrication, then sealing. It is possible there is a difference between the sealing on the different models however it doesn't seem to be something Shimano promote Cranksets with 30 mm wide spindles won’t fit into frames with BB86, or BB90 BBs, but with correct BB some can be made to fit into threaded frames.

If the frame has a press-fit BB shell (without threads, threadless), then you need quite expensive, special tools to install and remove/change BBs. If not using such tools (like a bearing press), bicycle frame can be damaged. Specialized uses PF30 for its high-end mountain bike, confusingly also calling it OSBB though it is a different standard to the OSBB standard found on its road bike. BB30’s larger 30mm-diameter spindle, compared to the standard 24mm size, allows the use of lighter alloy Immediate Media Pros: Lighter weight; more resistant to axle twist; more heel clearance; larger-diameter shell and spindle; potential for narrower pedal stance width There are three current Hollowtech II road threaded BB designs (different model numbers of identical designs also exist).

As it stands, this new standard may just become the hot new thing among smaller manufacturers of metal bikes. PF86’s wider shell allows the chainstays to be pushed further apart – a big advantage for ‘cross bikes Immediate Media Trek introduced the proprietary BB90 standard in 2007 on the revamped Madone and soon followed with the mountain bike-specific BB95. I think it’s more about the simplicity of the manufacturing process,” says Drew Guldalian of Pennsylvania-based custom builder Engin Cycles. “Boring out a [standard] BB30 is not impossible, but in my opinion it’s an unrealistic task from a manufacturer’s standpoint that needs to do something to make money. BB30 shells, however, do require more stringent dimensional tolerances to work well, meaning that they’re more expensive to manufacture. Moreover, with the notable exception of Felt, which uses a carbon tube, BB30 also usually employs an alloy shell insert that has to be bonded or co-moulded into an otherwise carbon frame.Cons: Heavier than press-fit systems; frame design limited by relatively small-diameter and narrow shell Other names PF41 (Hope – refers to BB shell diameter), PF24 (Chris King – refers to spindle diameter)