Bicycle Mechanics - New fork for my 58 cm Miyata

So I got nailed by a car Monday night and am just now getting around to assessing the damage... The front fork on my bike is severely bent and I think will need to be replaced. I am going to get this done professionally as I do not want to mess with the headset on my own. Can anyone tell me the appropriate size steer tube for a 58cm frame? my rough measurement came out to about 6.25 inches... does that seem right? also, it's an older bike with a threaded stem, anyone have any advice on maybe converting it to a threadless? Ultimately, I think I will buy a new fork and bring that to the bike shop to have them make the switch. Any help would be much appreciated... thanks!

So I got nailed by a car Monday night and am just now getting around to assessing the damage... The front fork on my bike is severely bent and I think will need to be replaced. I am going to get this done professionally as I do not want to mess with the headset on my own. Can anyone tell me the appropriate size steer tube for a 58cm frame? my rough measurement came out to about 6.25 inches... does that seem right? also, it's an older bike with a threaded stem, anyone have any advice on maybe converting it to a threadless? Ultimately, I think I will buy a new fork and bring that to the bike shop to have them make the switch. Any help would be much appreciated... thanks!Tried measuring the steerer length on the old fork? Dirty way is base of lower cup to top of locknut. Not exact,but close enough for buying another one.
Otherwise it's headtube length + stack height of the HS you intend to use.A bit long is better than too short. Threadless also means a new HS and stem + addingin the stack of the stem to get minimum steerer length. The Myita likely uses a JIS 1" HS with 27.0 crown race and 30. cups rather then the more common ISO 1" 26.4 CR and 30.2 cups If you don't know what you are doing,take it straight up to a shop that does, rather than buying stuff that no workee.

The Myita likely uses a JIS 1" HS with 27.0 crown race and 30. cups rather then the more common ISO 1" 26.4 CR and 30.2 cups If you don't know what you are doing,take it straight up to a shop that does, rather than buying stuff that no workee.

Maybe, maybe not. JIS tends to be used for the El Cheapo Japanese bicycles. Miyata is a quality brand (some of the best mass-production bikes of the 80's), and more likely to use ISO headset standards. However, we don't know the model or year of bicycle, and Miyata may have used JIS for its lower end cycles. I rather doubt it, but it's possible.

Short story is, if it's a Miyata from the 80's or later, it's probably an ISO headset standard (~90% sure), but if you don't want to take a chance, get it checked out first! If you're going to have this done professionally, you'll be having the shop check it out anyway.

Now's a great time to do two things:

1. Convert to aheadset - if you have bent a fork, it's likely that you'll need a new headset. Reasonable aheadset stems are not expensive, and you need a new fork. So with that in mind, you can upgrade your bike for the addtional cost of a stem ....

2. Upgrade to a carbon fork - IMHO carbon forks are the best upgrade that you can do to a road bike - they are light, relatively stiff, and really nice to ride (absorbant). Just make sure you get one that has carbon blades (at least - some will have a carbon crown, or even carbon steerer as well). Some cheapies are carbon wrapped over Alloy - and they really don't ride that nicely ....

Now's a great time to do two things:

1. Convert to aheadset - if you have bent a fork, it's likely that you'll need a new headset. Reasonable aheadset stems are not expensive, and you need a new fork. So with that in mind, you can upgrade your bike for the addtional cost of a stem ....

2. Upgrade to a carbon fork - IMHO carbon forks are the best upgrade that you can do to a road bike - they are light, relatively stiff, and really nice to ride (absorbant). Just make sure you get one that has carbon blades (at least - some will have a carbon crown, or even carbon steerer as well). Some cheapies are carbon wrapped over Alloy - and they really don't ride that nicely ....

Now's a great time to do two things:

1. Convert to aheadset - if you have bent a fork, it's likely that you'll need a new headset. Reasonable aheadset stems are not expensive, and you need a new fork. So with that in mind, you can upgrade your bike for the addtional cost of a stem ....

2. Upgrade to a carbon fork - IMHO carbon forks are the best upgrade that you can do to a road bike - they are light, relatively stiff, and really nice to ride (absorbant). Just make sure you get one that has carbon blades (at least - some will have a carbon crown, or even carbon steerer as well). Some cheapies are carbon wrapped over Alloy - and they really don't ride that nicely ....

I think the aheadset conversion is a reasonable thing to do. It wont make you go faster or anything but it is the current std.
If you want to retain a trad threaded headset, think about the stack height. If you cut a steerer for a low stack style of headset, you cannot fit one with a larger stack and low stack headsets are now only available in steel.
This is something for a bike shop to handle.

When my Miyata was run over the frame damage was to the rear triangle and bottom bracket shell; the fork is fine. It's yours if you want it.
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A bit long is better than too short.

True words of wisdom for so many things.

Thanks for the help everyone... i don't know too much about the bike' s specs, other than that it has a miyata headbadge... it was repainted, but apparently it is a 1983 model... i would guess the 710 or the 310? i don't have any of it's deraileurs but it's got sugino cranks and dura ace brakes. (but those could be aftermarket.) When I get up and moving around again I will take it in to the shop and get their advice. Thanks again!

Maybe, maybe not. JIS tends to be used for the El Cheapo Japanese bicycles. Miyata is a quality brand (some of the best mass-production bikes of the 80's), and more likely to use ISO headset standards. However, we don't know the model or year of bicycle, and Miyata may have used JIS for its lower end cycles. I rather doubt it, but it's possible.

Short story is, if it's a Miyata from the 80's or later, it's probably an ISO headset standard (~90% sure), but if you don't want to take a chance, get it checked out first! If you're going to have this done professionally, you'll be having the shop check it out anyway.That's a generalization that doesn't fly.I've seen them on some pretty good '80 vintage Japaneese bikes. Measuring always works.