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So I've got ekar chainset and pro tech bb, didn't have a correct bearings so fitted 6805 which are 7mm width, because its 1mm wider than original I've got +2mm over. Cannot see if it's pulling enough both chainset pieces. Do think it's safe? And did anyone tried similar combination before?

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  • I feel like this would cause wear on the spindle joint and damage the spindle halves...
    – Erlkoenig
    Commented May 14, 2023 at 18:53
  • That's what i thought as well, but its really hard to tell when it's inside the frame.. but yeah 2mm is quite big gap, so under pressure it will start showing wearing signs . Probably better not to risk and get 6mm
    – Virmantas
    Commented May 14, 2023 at 19:04

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For those who don't know, Campagnolo cranks use a non-standard version of the 6805 bearing that's 1mm thinner than the standard bearing. Thus, the standard bearings will push everything 1mm outward on each side.

Modern cranksets will not tolerate that amount of change in the system. Campy and Shimano cranks require a splined interface to engage. If you add 2mm of clearance into the system, the spline won't be fully engaged. Now imagine that you are pedaling. Almost all riders probably cruise at well over 100W of power, and peak power during a sprint is much higher. If you put that amount of power into a splined system that isn't engaged fully, the splines are going to get damaged.

For SRAM cranks, there is a preload adjuster to take up variations in BB width that are within the allowed tolerance of the system. However, it is not going to be designed to take up 2mm additional slack - that's the difference between the widths of BSA and Italian BB shells. Basically, the same issue will happen.

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  • Hi and thank you! You've been very informative! 🤝🏻 Appreciate your help
    – Virmantas
    Commented May 14, 2023 at 21:00
  • Done little bit more research on this one and find out that campag use 6805N bearing which is same 6805 37×25 but N stands for narrow which is 6mm instead of 7mm. At least it's clear now in my head 🧠 Thanks again for knowledge sharing! Any issues I will come back here. One love
    – Virmantas
    Commented May 15, 2023 at 6:02
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    @Akapat would you consider accepting this as the answer? this site works by upvoting and accepting answers.
    – Weiwen Ng
    Commented May 16, 2023 at 0:33
  • Yes, definitely! And thank you again.
    – Virmantas
    Commented May 16, 2023 at 19:01
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    The tolerance for threaded BBs appears to be ±0.5mm after reviewing SRAM and Shimano’s frame design documents. So a 2mm abnormality would be bad.
    – MaplePanda
    Commented Jun 15, 2023 at 6:02

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