pic: 4WD Concept

[Chris is me]

Originally Posted by AdamHeard

The bearings are spaced plenty far apart. Most teams that run 2 piece blocks (like 254) are counter boring the bearings anyway, yielding the same bearing spacing (or only .125" more).

The rigidity and concentrically advantage over most 2 piece blocks (as most 2 piece blocks don't adequately align to each other) is nice as well.

I didn't realize these were COTS bearing blocks when I made the post, which increases my confidence in them a lot.

That said, since the bearings are hex, I think there's at least an argument to be made to be paranoid about how heavily the bearings are loaded. This year, our bearings were spaced 1.75" apart (just happened to be, we didn't design around this problem) and we had no hex bearing failures. Other teams with bearings 1" apart or less had problems with some hex bearings exploding under regular drivetrain loads. Hopefully the manufacturing problems with hex bearings are cleared up for 2015 and we don't have to think about out of spec COTS parts when designing, but if you want to be paranoid it's something to consider.

An easier solution than going with a different bearing block would be to just turn that part of the shaft round and use round bearings (less prone to failure), or better yet use a dead axle bearing block (also available from 221) since your chain is on the same side as the wheels. But this might not even be a problem next year, so...