I'm assembling a 3T Exploro Team 2020. It seems like the fork has an integrated crown race. Should it be greased before assembly and pre-loading?
3 Answers
Yes, it should. Grease all the contact surfaces.
answered Jan 5, 2021 at 16:10
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@T0TTE Doesn’t really matter, since bicycles aren’t a very demanding application. That said, any bike branded grease will do, or NGLI class 2 grease from the hardware/automotive store. I personally use this: amazon.ca/Super-Lube-41160-Synthetic-Multi-Purpose/dp/… Commented Jan 5, 2021 at 21:54
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1Super Lube is an awesome product. Clear/translucent, waterproof, PTFE additive for better lubricity and a lower viscosity that is more appropriate for bicycle applications are the top characteristics that make Super Lube my go to grease for bikes.– JeffCommented Jan 25, 2021 at 12:46
It seems like the fork has an integrated crown race. Should it be greased before assembly and pre-loading?
Current headsets have a conical or spherical seat for the cartridge bearings. The purpose of this seat is to absorb shocks that the bearing would be unable to otherwise absorb. This absorption requires the seat to be greased. With no grease, it won't absorb these shocks as reliably as it would with the grease.
Why is this shock absorption so critical, then? Before the conically or spherically seated cartridge bearings, headsets had the bearings directly running on the crown race and the cups. Because these bearings cannot absorb shocks similarly, older bicycle headset bearings tended to develop so-called "indexed steering" where the steering of the bicycle has a notched "home" position in the middle so that turning the fork away from the unsteered position required slight force.
This "indexed steering" is not dangerous but it is annoying.
If you leave the conical/spherical seats of the cartridge bearings ungreased, you are increasing the risk of the headset bearings developing this "indexed steering" annoyance.
Thus, all (top and bottom) interfaces of both headset bearing cartridges require lubrication.
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Do you have a reference that backs up what you are saying? Commented Jan 6, 2021 at 1:23
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1I'm not sure I buy the argument of a greased integrated crown race preventing indexed steering pits in a cartridge bearing. First, there is no direct contact between the fork crown race and individual bearing balls as the lower part of the cartridge bearing, angled to mesh with the angle of the crown race separates the crown race and the bearing balls. Further, this lower aspect of the cartridge bearing acts to spread the load more evenly. The overall design does far more to prevent indexed steering than grease on the crown race– JeffCommented Jan 25, 2021 at 13:11
My gut instinct says no grease. Point one, The Park tool manual makes no mention of applying grease to the fork. Second point is that generally you don't want grease in continuous contact with carbon fiber. Third point is that by lubricating the interface you risk the inner race spinning on the fork. The idea is for the fork and inner race to move at the same time, while the outer race stays fixed in the headtube. If the inner race were to slip on the fork it could cause severe damage to the fork. It is the same logic as to why you don't grease handlebar clamps or stems.
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1The injunction to not grease carbon fiber is apparently a myth. Paint remover does dissolve the resin, but grease is not paint remover. velonews.com/gear/… Commented Jan 5, 2021 at 21:40
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The loose inner race won’t happen with a properly adjusted headset. The bearing should be much easier to spin than spinning the race on the crown. Without grease, you potentially risk having Swifty’s corrosion nightmares. Commented Jan 5, 2021 at 21:58