ZRACE RX dub crankset... preload?

[mrdawson]

see link for exact crankset with magene p505 PM.
https://www.aliexpress.com/item/1005004272205793.html?spm=a2g0o.order_list.order_list_main.53.13f21802QU9SXd

---going to be using this on frame with t47BB...  Have not attempted install yet, but the problem I am foreseeing is with BB preload... every other dub crankset I've ever seen has a way to set / adjust preload.  I see no way of doing this with these cranks other than hope / pray the washers provided are exactly the correct size you might need.

thoughts?

[acedeuce802]

I've got this crankset on 2 bikes, one with BSA68 and one with BB86, both used with ZRACE BB's.  You are correct that there is no preload adjustment.  If I remember right, there's a wave washer to take up the slop, which buys you just a tiny bit of room for error.  I couldn't find info on which size spacers were needed where, so I installed the crank with no spacers and centered the cranks, then measured the gaps.  The gap was a nominal value which matched what was included in the ZRACE BB, and when torqued up with spacers there was no slop, but also no excessive drag.  So it worked out in my case, but I could also see that if there's manufacturing tolerances in the BB shell that there could be issues.

[mrdawson]

I've got this crankset on 2 bikes, one with BSA68 and one with BB86, both used with ZRACE BB's.  You are correct that there is no preload adjustment.  If I remember right, there's a wave washer to take up the slop, which buys you just a tiny bit of room for error.  I couldn't find info on which size spacers were needed where, so I installed the crank with no spacers and centered the cranks, then measured the gaps.  The gap was a nominal value which matched what was included in the ZRACE BB, and when torqued up with spacers there was no slop, but also no excessive drag.  So it worked out in my case, but I could also see that if there's manufacturing tolerances in the BB shell that there could be issues.

- Thanks for the info.  Yes, this is exactly my concern... Does not seem to be any room for potential error in the BB shell / BB widths.  Hence why every other dub crank in existence has the preload ring ha.