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Fork crown length?

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Fork crown length?

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Old 01-31-19, 09:47 AM
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dr1445
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Fork crown length?

i am looking at older 20" and 15" hybrid frames, 700c, 1 1/8" tube with straight wall. these frames came from the oem with rigid forks. i will be looking for forks for them, what crown length will work, 370mm? thanks
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Old 01-31-19, 10:16 AM
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I am confused , your nomenclature is perhaps misused .. fork crown is the piece that joins steering tube and 2 fork blades,

are you scratch building your own fork , or just want forum members to search the web for you?

when you buy a new fork say through a bike shop they come uncut often 300mm long steerer tube in the center of a fork crown
with your seat for the crown race at the base of it, but not the actual race, that's part of the headset..bearing assembly..

going with your bike into a brick and mortar bike shop will help clarify your options text on this site cannot...

blade length and rake/offset have effect on how the bike steering will feel..
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Old 01-31-19, 04:18 PM
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crown length = the distance from the axle to the fork crown just below where the crown race would sit.
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Old 01-31-19, 07:34 PM
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The usual term is axle-to-crown.

If you are looking at 'older' hybrid frames, designed for 700c wheels, then probably the original forks are somewhere between 370mm a-c ('road') to 390mm a-c ('cross').

That's as specific as anyone could get, absent knowing precisely which frame(s) you are talking about, what year of production, and so on.

If you are indeed 'looking' at such frames, pretty simple to measure the forks -- assuming the forks are present. If they are not, then more information would be necessary before anyone here could give a useful response.
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Old 02-01-19, 04:29 AM
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the reason i asked is there are no forks with the ebay frames and replacement forks are no longer available due to age. there is plenty of info on replacing suspension forks with rigid, but i could find zero on city bikes that came with rigid forks. thanks.
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Old 02-01-19, 07:48 AM
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370mm would probably work for the 28mm tires you plan to use; however if you think that wider tires (which will be taller as well) or fenders will be needed, best to go longer.
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Old 02-02-19, 10:15 AM
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The advent and popularity of disc brakes has made this more confusing, because many forks will handle at least two wheel sizes ...

And added suspension travel had added some complexity. If moving an older frame to a longer travel fork, it will change steering geometry some. But if say an air fork is set up with 1/3 sag, it could be almost the same nominal geometry as the previous spring fork with little sag.

Air forks can be quite light, in the 1600 gm range is doable for not terrible money in the used market.

Rigid forks can be heavy or light, stiff or springy.

So what frames are you looking at, and what is your end goal?
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Old 02-03-19, 08:52 AM
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the frame i purchased is an older marin sausalito frame with a straight top tube. there are several different model marin frames on ebay. it looks like the sausalito model has a suspension fork up front and will need a 29er corrected rigid fork.
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