Bike Forums

Bike Forums (https://www.bikeforums.net/forum.php)
-   Bicycle Mechanics (https://www.bikeforums.net/bicycle-mechanics/)
-   -   BB Spacer/Headset Preload (https://www.bikeforums.net/bicycle-mechanics/1243554-bb-spacer-headset-preload.html)

Rdmonster69 12-11-21 09:49 AM

BB Spacer/Headset Preload
 
I have done builds before but they have been mashups with used parts etc and I never seriously asked these questions before.

1. I am installing a new Dura Ace crankset into a Chris King BB. How do I determine if I need the spacers included with the fit kit. The inner chainring is no closer to the chain stay than my other bikes. If I was assembling today I would probably just go for it and see if it worked OK and ad spacers if needed. If someone can tell me how to determine this beforehand that would be great. I am using a DA 11-30 cassette.

2. I have a Chris King No Threadset headset that I pressed in. It is flush with the steering tube and solid in all respects. I have a 1 inch fork with a shim, stem and carbon spacers. When fit together (but not tightened)there is very slight movement when rocking the fork. My thought is some pressure on the stem to provide slight tension/downward pressure then in the assembly should eliminate this then tighten the stem. Am I on the right track or is there a definite technique. I have used this technique before with success on a different bike but with a different headset.

3. Should the steerer tube be flush with the spacers or slightly recessed when installing and tightening the star nut. I can't remember for the life of me how I did it the last time.

This is a 2000 model year Lightspeed Classic Ti frame. All components are modern 9100 Dura Ace mechanical

Also ,if your just going to comment to tell me I'm stupid and don't know what I'm doing , Please save it. I shouldn't have to ask for that courtesy but unfortunately I do.

Thanks in advance.

cyccommute 12-11-21 10:10 AM


Originally Posted by Rdmonster69 (Post 22336512)
I have done builds before but they have been mashups with used parts etc and I never seriously asked these questions before.

1. I am installing a new Dura Ace crankset into a Chris King BB. How do I determine if I need the spacers included with the fit kit. The inner chainring is no closer to the chain stay than my other bikes. If I was assembling today I would probably just go for it and see if it worked OK and ad spacers if needed. If someone can tell me how to determine this beforehand that would be great. I am using a DA 11-30 cassette.

Assuming a 68mm bottom shell width and a 73mm bottom bracket , you should probably start with two 2.5mm spacers on the right and one on the left. If the bottom bracket is a road bottom bracket that is 68mm wide, you probably donít need any spacers.


2. I have a Chris King No Threadset headset that I pressed in. It is flush with the steering tube and solid in all respects. I have a 1 inch fork with a shim, stem and carbon spacers. When fit together (but not tightened)there is very slight movement when rocking the fork. My thought is some pressure on the stem to provide slight tension/downward pressure then in the assembly should eliminate this then tighten the stem. Am I on the right track or is there a definite technique. I have used this technique before with success on a different bike but with a different headset.
Yup. Thatís the way you adjust the bearing preload. Donít make it tight enough to bind the headset but also donít make it loose enough to allow for movement


3. Should the steerer tube be flush with the spacers or slightly recessed when installing and tightening the star nut? I can't remember for the life of me how I did it the last time.
Slightly recessed. It needs to be about 3mm (bit more than a US nickel) so that the cap doesnít sit on top of the steer tube.

Rdmonster69 12-11-21 10:24 AM

Score !! Thanks Cyco !! It is a 68mm BB and everything is road standard so I probably wont need the spacer but have it if I need it. Glad I was essentially on the right track.

Rick 12-11-21 11:32 AM

I recently put a Chris King BB on my Rohloff equipped bicycle. Prior to taking of the old crank I measured from the seat tube to the top center of the belt ring to have the proper belt alignment. I called Chris King about the preload and they said any feeling of play would lead to a damaged BB.

Rdmonster69 12-11-21 11:55 AM


Originally Posted by Rick (Post 22336606)
I recently put a Chris King BB on my Rohloff equipped bicycle. Prior to taking of the old crank I measured from the seat tube to the top center of the belt ring to have the proper belt alignment. I called Chris King about the preload and they said any feeling of play would lead to a damaged BB.

I can feel no play at all in the BB. Its solid as a rock. Almost imperceptible play in the headtube. Pretty sure it will be easy to preload.

HillRider 12-11-21 01:24 PM

Chris King recommends a preload of about 4 to 10 inch-pounds on their headset top bolts. This assures no play but no binding either.

The steerer top should be about 3mm below the top of the stem or top spacer. I like to cut my steerer so it sticks out about 7mm above the top of the stem and then use a 10mm spacer above the stem to give that 3mm gap. This way the steerer is fully supported by the stem which isn't critical for a steel steerer but highly desirable for a carbon steerer. I trust you haven't installed a starnut in a carbon steerer.

Rdmonster69 12-11-21 04:57 PM


Originally Posted by HillRider (Post 22336702)
Chris King recommends a preload of about 4 to 10 inch-pounds on their headset top bolts. This assures no play but no binding either.

I trust you haven't installed a starnut in a carbon steerer.

My fork has an aluminum steerer as have the other forks I have installed a star nut in. Is there a special procedure for carbon forks ?

Andrew R Stewart 12-11-21 05:58 PM

Carbon steerers don't like the gauging aspect of star nuts. Also carbon tubes are not the best at holding up to compressive forces so some sort in the top of the steerer reinforcement and preload draw bolt threading is needed. We call these pressure plugs. A few get bonded in place, most have an expanding inside the steerer design. Andy


All times are GMT -6. The time now is 04:37 PM.


Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.