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Installing steel fork into alu headtube (Montague bike)

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Installing steel fork into alu headtube (Montague bike)

Old 05-13-19, 06:34 PM
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Morimorimori
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Installing steel fork into alu headtube (Montague bike)

Hi, everyone.

I previously created a topic about searching for steel threadless fork which would suite my other aluminum frame. Here it is: Looking for a rigid fork with CrMo steerer tube which will fit my Montague Urban bike

I was able to find a fork, and now try to install it. I have one issue with it, though.

As previously mentioned in that topic, my alu head tube has rather wide ends, like it would need a cone tube steerer at a fork. Somebody suggested it's just decorative parts - and that happened to be true, I dropped the original fork and it has straight steerer (1-1/8", 28.6 mm outer diameter). But the crown race it uses bothers me. It has rather wide base, way wider than the crown of my new steel form. It actually covers the wide crown of alu fork mostly. And it doesn't want to "sit firmly" on my new fork. It looks a bit like a cone - Its upper inner diameter seem to match, but lower inner diameter is a bit bigger than the crown of the steel fork, so it hangs from it, instead of be mounted on the crown firmly.

Here is a picture of it, I believe (I forgot to make a picture of my own, and already have assembled the bike) - it's the last one to the right, called for some reason a "dust cover":



I wonder, what should I do? Is this fork just incompatible with such a tube? Or should I just find a crown race which matches my steel fork? What kind of crown race is it, which sizes?
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Old 05-13-19, 06:35 PM
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Here are 3 pictures from my old topic, showing how my new fork and my headtube look like:



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Old 05-13-19, 07:50 PM
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So are the two forks' steerers of the same diameters and such? Are you sure the "crown race" is not a simple seal that sits on a crown race? Carbon forks often have a larger cross section at the crown although the crown race seat can remain the same.

This post is somewhat confusing tom me as I'm not completely sure what's being described, the bearing race or a seal, whether the new fork also had a crown race on it already. Once again the complexity of a headset and fork change proves to be more then anticipated. With more description (photos!) I might understand all that's going on and give a more helpful answer. Andy
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Old 05-13-19, 08:34 PM
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It looks like you have a 44mm head tube at the bottom end, can't see the top. Cane Creek among others make adapters to fit 1 1/8 straight steerers into the 44mm head tube. Google search for adapter for 1 1/8 steerer to 44 mm head tube.
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Old 05-14-19, 04:00 AM
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Your aluminum fork had a tapered piece added to the crown race seat in order for it to have a cleaner looking transition to the head tube, which appears to be a 44mm head tube. The new fork does not have that and its not necessary, but it is not a visually pleasing transition. That is just the way it works when you install a straight steerer steel fork in a 44mm head tube. As long as you have properly pressed on the crown race to your new fork and it sits flush with the crown race seat, there is no problem.
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Old 05-14-19, 04:43 PM
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Hi, everyone.

Sorry for the delay. I've dropped the old fork again, to make some photos. First, I'll answer some questions.


Originally Posted by Andrew R Stewart View Post
So are the two forks' steerers of the same diameters and such?
Correct, steerers are the same.

Originally Posted by Andrew R Stewart View Post
Are you sure the "crown race" is not a simple seal that sits on a crown race? Carbon forks often have a larger cross section at the crown although the crown race seat can remain the same.
It's not carbon, but you seem to be right - what I confused for crown race is some kind of dust cover, or adapter which was sitting on top of actual crown race (see photos below)
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Old 05-14-19, 04:44 PM
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Originally Posted by wsteve464 View Post
It looks like you have a 44mm head tube at the bottom end, can't see the top. Cane Creek among others make adapters to fit 1 1/8 straight steerers into the 44mm head tube. Google search for adapter for 1 1/8 steerer to 44 mm head tube.
I took out the lower bearing and measured it's outer dimater - it's 40mm exactly (see photos below)
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Old 05-14-19, 04:48 PM
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Here are the photos.

This is how original fork look like:



As you can see, the dust cover/adapter I mistook for crown race has outer diameter exactly matching diameter of alu fork's crown, it covers it completely. The bearing is sitting on top of that cover/adapter.
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Old 05-14-19, 04:51 PM
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This is how the head tube looks like from below:
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Old 05-14-19, 04:56 PM
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And this is what happens when I just take that dust cover/adapter thing with the bearing and try to move it to the steel fork. The dust cover thingy has inner radius of 37mm, which is wider than the crow of the steel fork, so it's not sitting right at it, it falls through. The bearing itself are somewhat wider than the steerer tube (bearing's inner radius is ~32-33mm, outer radius is 40mm), so they are not sitting firmly as well (on the alu fork they are sitting properly on the dust cover):


Last edited by Morimorimori; 05-14-19 at 05:01 PM.
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Old 05-14-19, 04:56 PM
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Here is the actual crown race of the alu fork, which has been hidden under that dust cover:

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Old 05-14-19, 05:00 PM
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So, my understanding is that I need some kind of adapter which will be as wide as the old (alu) fork's crown, so it would server as a proper foundation for that dust cover thing needed to hold bearing in place properly? Something like this, may be?


Or this?


Or do I just need a suitable crown race for the steel fork?
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Old 05-14-19, 05:05 PM
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To clarify this: the "dust cover / adapter" thingy I constantly mention, though isn't shown on photos very well, is still very similar to the most right part on the photo in the first post here. I think mine may have wider outer radius, but overall it looks very like this one.
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Old 05-14-19, 07:36 PM
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I believe that dsaul has it right. The fork crown has a wide pad for the crown race (and it's seal) to rest on. The seal and pad are large enough in diameter to blend in with the head tube. There looks to be a steel insert for the lower head tube cup. This, the loose ball type, the non specific crown race all point to a low cost spec. The crown race seems to have a step in it's lower OD, perhaps to seat the seal. I take it that without the old fork's pad the seal will just flop about? Andy
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Old 05-14-19, 09:01 PM
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Did the fork come with a crown race? If so do you know which size, there are 2, I can't recall the names but they are only a few dollars each.

If you are still haveing trouble buy a dial caliper, cheap one from ebay will work.

Go here https://blue.canecreek.com/headset-fit-finder input measurements.

they also carry adapters from 1 1/8 crown race to the larger sizes.

Good luck
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