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1 1/4" fork in a 1 1/8" headtube

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1 1/4" fork in a 1 1/8" headtube

Old 12-04-20, 02:43 PM
  #1  
Shinkers
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1 1/4" fork in a 1 1/8" headtube

Hello,

I've searched this but am having a hard time finding information that is pertinent to my situation.

I have a frame that takes EC34 cups, and a 1 1/8" straight steerer fork. I happen to have a 1 1/4" fork that'd be nice to use in the frame. It would seem like with external cups, a person might be able to squeeze the larger steerer fork into the head tube, so I'm wondering if anyone has experience with this. So far I'm striking out.

Thanks!
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Old 12-04-20, 03:06 PM
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I'm not aware of anyone making an EC34 lower for a 33mm crown race. The math just doesn't work unless you make the cup stick out much further than normal, in order to clear the tapered steerer. The crown race diameter of 33mm and internal head tube size of 33.95-33.98mm leaves very little room for the part of the cup that gets pressed into the frame.
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Old 12-04-20, 03:10 PM
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I'd get one that fits. Or at least get the fork steerer tube replaced with one that fits - although that would probably be as expensive as a new fork.
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Old 12-04-20, 03:13 PM
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Won't work. If such an adaptor were made it would jack the front of the bike up by the height of the tapered 1 1/4 section, ie. about three inches. You bike would not like this, and likely neither would you.
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Old 12-04-20, 08:55 PM
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There is no safe or non-geometry altering way to do this. I am sure someone could custom machine cups and do some craziness but as dsaul and ClydeClydeson said it would make the front of the bike sit up too high and change the geometry quite a bit.

What kind of fork do you need. Plenty of awesome straight steerer forks out there even plenty in full carbon with all the mounts and such and with suspension you still have great options. Basically there isn't a huge need to go crazy when fork options exist in all the popular stuff people are usually looking to convert over.

I will say if you ever do a custom frame you might consider a 44mm head tube and then you can go with a tapered or straight steerer fork with the right cups.
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Old 12-04-20, 11:53 PM
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Originally Posted by veganbikes View Post
There is no safe or non-geometry altering way to do this. I am sure someone could custom machine cups and do some craziness but as dsaul and ClydeClydeson said it would make the front of the bike sit up too high and change the geometry quite a bit.

What kind of fork do you need. Plenty of awesome straight steerer forks out there even plenty in full carbon with all the mounts and such and with suspension you still have great options. Basically there isn't a huge need to go crazy when fork options exist in all the popular stuff people are usually looking to convert over.

I will say if you ever do a custom frame you might consider a 44mm head tube and then you can go with a tapered or straight steerer fork with the right cups.
The availability of straight-steerer forks depends on what sort of fork you're looking for - I'm assuming that the OP is looking for a road fork, as opposed to an MTB fork - if so, it depends on what sort of fork (disk vs rim) you're looking for - recently I pondered adding a front disk to my 1 1/8"-headtube frame, and there are very few 1 1/8"-steerer disk forks out there. They're not nonexistent, but they're certainly thin on the ground
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Old 12-05-20, 02:48 PM
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Originally Posted by Litespud View Post
The availability of straight-steerer forks depends on what sort of fork you're looking for - I'm assuming that the OP is looking for a road fork, as opposed to an MTB fork - if so, it depends on what sort of fork (disk vs rim) you're looking for - recently I pondered adding a front disk to my 1 1/8"-headtube frame, and there are very few 1 1/8"-steerer disk forks out there. They're not nonexistent, but they're certainly thin on the ground
They are thinner for sure but not super thin. Here are some options:
https://www.fyxation.com/products/ca...adventure-fork
https://www.fyxation.com/collections...ad-carbon-fork
https://www.woundupcomposites.com/pr...-x-disc-1-1-8/
https://us.ritcheylogic.com/us_en/wc...ss-gravel-fork
https://us.ritcheylogic.com/us_en/wc...re-gravel-fork
https://us.ritcheylogic.com/us_en/wc...road-fork-2020
https://whiskyparts.co/forks/no.7-cx-disc-straight#/
https://whiskyparts.co/forks/no.9-cx-disc-12-straight#/
https://www.interlocracing.com/shop/...thru-axle-4590
https://www.interlocracing.com/shop/...-1-1-8-qr-4589
https://cinq.de/en/carbon-forks/393/cinq-touring-fork
https://www.somafab.com/archives/pro...el-carbon-fork
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