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I'm in the process of building up a new bike from scratch. Since the last time I have done this many things have changed, reading varios forums and watching numberless videos on YouTube have not helped.

I have a carbon frame with a carbon fork without a crown race. The crown race is laminated into the fork. The bottom bracket is a press fit one.

Now what is the best way to install the integrated head set and bottom bracket. Some suggest to dry fit the bottom bracket, other grease it, yet other use Loctite.

Various forums suggested Loctite 641 or it's stronger form 609. There seem to be various opinions if one should use the Loctite activator 7471 or not. Also some say you must clean the frame with a special Loctite cleaner before applying.

I have settled to use only Loctite 641 without the cleaner and activator, as I see no benefit in using both. The contact points can be cleaned with alcohol or similar. The activator will only speed up the process from 30min down, I'm in no rush here.

But will the Loctite cure without the activator, and is this the best/correct way to do this. Obviously I want to be able to remove and replace this parts if they wear down.

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  • What did you end up doing? I'm about to build up a titanium frame with press fit headset and press fit bottom bracket.
    – Ben Mills
    Commented Feb 22, 2016 at 20:03
  • I used the Loctite 641 and it is working fine ... have made about 1000km so far and no clicking or screatching sounds so far from the fork or bottom bracket. But due to cold and bad wheater I have not made any hill climbs where those areas are under full stress. I was quite concerned putting this on a carbon frame but once it cures it's like a paste. PS: I had quite a hard time getting the Loctite where I'm from, so first I have done it with normal screw/bolt securing fluid, which was working also fine. So if you can not get it use this.
    – Drejc
    Commented Feb 23, 2016 at 13:04

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As a general rule: if the manufacturer says it's press fit, then it really is press fit meaning it will be plenty tight after normal installation, and also meaning that because of the small tolerances any extra layer (like loctite) will make it harder to fit.

Not saying there aren't exceptions but none of the press fit bike components I ever installed had problems or became loose. In fact before I had the proper tools for press-fitting I just used to hammer the components into the frame and when you do that it is obvious you don't need extra: it takes some serious meticulously aimed hammer strikes to get the cups in. No way they are going to loosen. Same story getting the cups out again: it takes sheer force - but the adequate tools provide this. Just to illustrate you should not need anything special at all for installation/deinstallation.

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Install following the manufacturers' specifications. If they don't recommend Loctite, then don't use it. It might affect the carbon compound of the frame. In no case I would use Loctite on the headset since these part need to be taken apart, reassembled and readjusted frequently.

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  • Loctite 641 is intended for disassembly it is not a permanent bound. I is meant to prevent squeeking and to fill minor voids. The manufacturer didn't provide any info about installation.
    – Drejc
    Commented Oct 10, 2015 at 8:13

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