Solid axle locknut tightness

I've just converted and rebuilt a quick release disc hub into a solid axle bolt-on fixed gear rear, perfectly spaced for chainline etc.

I have 20mm of spacers on on one side and 15mm of spacers on the other, between the respective cone and locknut.

Now how tight does the locknut have to be against the spacers and cone? I was a bit worried, if it is too loose, could the cone on right hand side not push against the bearings and seize up the wheel while riding or am I not seeing it right?

Cheers

Ah the old how tight questions. Tricky to answer on the internet.

You just need to make sure the locknut doesn't come untightened from the cone, throwing out your nice adjustment on the cone which takes ages to get right. Although solid axles are easier than QR axles to adjust.

Well, I use the standard Park Tools home workshop cone spanners which are 4" or so long, and I do them up "firmly". They are thin metal wrenches, they aren't digging into my hand or hurting or anything like that. Not putting any body weight through. Just snugged down and then an extra 1/8th of a turn I guess. Think more "stem bolt clamp" than "bottom bracket" :o)

I'm not sure about seizing the bearings... If one of the locknuts comes undone the rim will start moving laterally on the hub, which will just feel nasty to ride on and if left (for a long time) will lead to failure of the cone/cup surfaces.

Thanks for your knowledge. I think I did it correctly. I tightened the locknuts to the strength it takes to close a jar of pickles firmly, just until it felt tight enough basically.

Also, on the bearings, I think I have it right. I put quite a bit of grease in with the bearings, tightened up the cones until I just felt the slight pressure of the cone pressing on the bearings, then backed off just enough for it to feel loose (fraction of a turn).

When I spin the axle on the hub it does have some resistance but still turns freely. Is it right to feel some drag when turning the axle round in the hub with your fingers?

Can be fine line between too loose and too tight. You will sometimes feel some drag when turning the axle with your fingers but would hope not to feel any when you spin the wheel. Sometimes if you leave it just a little loose the pressure when you clamp the wheel in tightens it just enoughn to make it perfect. Hard to describe in words....

I tightened the locknuts to the strength it takes to close a jar of pickles firmly

This needs to be the new measurement of tightness. Never mind your silly torque-wrenches!

You don't need a torque wrench! Unless, of course, you're working with kabon.

better to be slightly less tight than too tight. less tight on the cones will then be sorted out a bit by the tightness through the axle nuts when wheel is in fork/frame.
Too tight you can total the bearing surfaces or on cheaper hubs actually push the bearing races out of whack.
You might also find that you need to inject fresh grease into there after a week or so of riding as it sorts itself out in there. Then recheck cone tightness/ bearing play.

AFAIK what you aiming for is an axle that can be rotated without any gritty feeling, turns free enough though there will be a fair bit of resistance from the grease and should have a knatts whisker of play (almost unmeasurable, but can be just felt with the fingers).

I tightened the locknuts to the strength it takes to close a jar of pickles firmly, just until it felt tight enough basically.

Sounds perfect!

A well adjusted hub will have the same amount of friction to the fingers as when the cones are too loose, but with no discernible side to side play in the axle or side to side play when you wiggle the rim in the bike. Definitely no grittiness or tight spots.

In my opinion solid axle hubs don't deform like quick releases do so there is no need to leave a bit of play off the bike. A good adjustment off the bike is a good adjustment on for the solid axle. QR is a pain though.

In my opinion solid axle hubs don't deform like quick releases do so there is no need to leave a bit of play off the bike.

Not just an opinion, an actual science fact. There is no end to end compression of the axle with track nuts, whereas a good QR can put about a ton of pressure on the axle, so it's no wonder it compresses a bit, pushing the cones together and taking up the bearing free play.