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Discussion Starter · #1 ·
Hello everyone,

I am venturing into the single speed realm by purchasing a 2000 Airborne Sky Hag SS. Steel frame. I am excited!

This bike will need a fork. I believe I will go with a rigid. The bike originally came with a 80mm fork. I want to know if I should stick with that or if it is okay to go with 100mm? I did some homework and I think the biggest thing to worry about is stress on the headtube, correct?

Just looking for opinions, but for those 'in the know' would this be an okay move or should I keep her as originally intended?

I'm in Florida and ride trails that range from fast and flowing to more technical in nature with short but steep climbs and descents... No big air, no huge drops, etc...

Thanks in advance for any input-

J.
 

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Hello everyone,

I am venturing into the single speed realm by purchasing a 2000 Airborne Sky Hag SS. Steel frame. I am excited!

This bike will need a fork. I believe I will go with a rigid. The bike originally came with a 80mm fork. I want to know if I should stick with that or if it is okay to go with 100mm? I did some homework and I think the biggest thing to worry about is stress on the headtube, correct?

Just looking for opinions, but for those 'in the know' would this be an okay move or should I keep her as originally intended?

I'm in Florida and ride trails that range from fast and flowing to more technical in nature with short but steep climbs and descents... No big air, no huge drops, etc...

Thanks in advance for any input-

J.
From what I remember of Florida, you could go rigid or 80mm should be enough to soak up the roots. 100mm will be fine, just slower steering and lethargic handling.
 

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Since you are going with a rigid fork, you would probably want to keep the bike at the manufacturer's recommended "travel". Buying a fork with the same axle to crown (A-C) distance as a typical 80mm fork or buying a fork that is "suspension corrected" for 80mm is your best bet. Increasing the A-C distance to that of a 100mm travel fork will increase the stress on the headtube especially with a rigid fork not absorbing any of the impact and impulse forces.

To be on the safe side, I would contact Airborne about this. They're good with C/S it seems and they might even have a rigid fork recommendation.
 

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Hello everyone,

I am venturing into the single speed realm by purchasing a 2000 Airborne Sky Hag SS. Steel frame. I am excited!

This bike will need a fork. I believe I will go with a rigid. The bike originally came with a 80mm fork. I want to know if I should stick with that or if it is okay to go with 100mm? I did some homework and I think the biggest thing to worry about is stress on the headtube, correct?

Just looking for opinions, but for those 'in the know' would this be an okay move or should I keep her as originally intended?

I'm in Florida and ride trails that range from fast and flowing to more technical in nature with short but steep climbs and descents... No big air, no huge drops, etc...

Thanks in advance for any input-

J.
While we aren't the same "Airborne" as the old Airborne that originally made your frame, I used to work for that company back in the day. I will tell you that back then the standard policy was to tell customers the warranty was void if they put a fork with a longer A/C measurment than what the frame was based upon, so putting a 100mm fork on a frame meant for 80mm was a no-no.

Would it still be OK? Probably. But it will put more stress on the HT junction areas and on those frames IIRC they had body filler around all of the welds to make them look smooth and seamles. The filler may crack with added stress, actually I would bet on the fact that it will crack. That will be cosmetic only but still you may not like that.

I'd put an 80mm on that and call it a day.

Jeremy
 

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Below is a photo (taken yesterday) of an aluminum frame originally spec'd with an 80mm fork, on which I run a Surly Instigator fork suspension-corrected for 100mm.

Axle to crown on 80mm forks tends to fall between 450mm and 460mm. The Instigator's axle-to-crown is listed at 447mm.

I bought the frame purposely so that I could run a rigid bike without the added steepness that resulted when I ran the Instigator on a frame designed for 100mm travel.

I'm not saying "it's ok". I'm just sharing what is working so far for me. I built the bike as a winter beater, but for some odd reason I've liked it so much that it's been my main ride this season. Go figure.

p.s.: That rocky line you see the bike sitting on is the trail.

Bicycle wheel Tire Bicycle tire Bicycle frame Wheel
 

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Discussion Starter · #6 ·
Hey, thanks for the responses everyone. It definitely helped me get my mind around this. It's still a little overwhelming, though...

So, my bike originally had a Rock Shox Judy XC which was 80mm. The A/C for that was 451mm from what I can tell. So I would be fine with a Surly 1x1 which measures 453mm? A little longer than the Instigator, but weighs in at 100g less.

@BigDaddyFlyer: I'll consider you a qualified expert considering your background with the actual company so does that sound right to you? Or would you still suggest a rigid designed at 80mm? That would be the Surly 1x1 corrected for 80mm which the A/C is 413mm. It's probably interesting to be around a company for that long and see it change hands, etc... I bet you got some stories to tell...

@JonathanGennick: Thanks for the input. That steered me to a good search term for info. Where is that trail at? I would love to ride that. Many trails here in florida are similar, but with roots replacing the rocks :)

Thnaks again everyone!
 

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@JonathanGennick: Thanks for the input. That steered me to a good search term for info. Where is that trail at?
It is the North Country Trail on the 4km segment between the Forestville Ski Trail and the City of Marquette's tourist park. Where I'm at is closer to the city.

I would love to ride that. Many trails here in florida are similar, but with roots replacing the rocks :)
Plenty of roots on that trail too. It just depends upon where you're at on it. I can't ride all of it either. I can ride what you see in the photo, but I also did enough hike-a-bike yesterday to have me feeling pretty discouraged in spots. But then I met some better riders who dropped a few kind words on me, and life was good again.
 

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Basically if you get something around the 440mm-450mm height it'll be like riding around with the fork topped out, no sag. You will be shifting weight rearward and slackening out the head and seat angles while adding bottom bracket clearance.

Something along the lines of 420-430mm height would be the equivalent of riding around with a sagged in 80mm fork. You'll have a lower center of gravity with your weight more balanced between the tires.

The "added steepness" is completely incorrect as a properly 'suspension corrected' rigid fork will set the bike up where it would be at normal ride height with a suspension fork. Some folks want to play with their setups more by altering rigid fork height and axle offset since you can adjust head angle, rake, and trail indepently to make the bike handle how you like.

Go with the shorter of the Surly 1x1s and you'll be fine (420mm IIRC). The 453mm 1x1 and the 447mm Instigator forks will be too tall and you might have issues weighting the front end during cornering and climbing.
 

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Hey, thanks for the responses everyone. It definitely helped me get my mind around this. It's still a little overwhelming, though...

So, my bike originally had a Rock Shox Judy XC which was 80mm. The A/C for that was 451mm from what I can tell. So I would be fine with a Surly 1x1 which measures 453mm? A little longer than the Instigator, but weighs in at 100g less.

@BigDaddyFlyer: I'll consider you a qualified expert considering your background with the actual company so does that sound right to you? Or would you still suggest a rigid designed at 80mm? That would be the Surly 1x1 corrected for 80mm which the A/C is 413mm. It's probably interesting to be around a company for that long and see it change hands, etc... I bet you got some stories to tell...
Yep, you should be just fine with that Surly fork. I ran a custom fork back in the day on my Ti Hag (single speed version of the Lucky Strike) with the same A/C and it was perfect.

I have A LOT of stories to tell................LOL..............;).........but if I did I'd have to kill ya.
 

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Discussion Starter · #10 ·
Well, I ordered the Instigator fork. I figure that the worst case scenario if I don't like the feel is that I put it on the beater Mongoose that is my loaner bike. It would be a good upgrade from the POS pogo fork on it now.

So, all I have to do is wait for it to come in... My Sky Hag arrived today and I could not be more excited! OMG, that this really oozes quality. At least, it does to me. My current ride is a Sette Reken, which I really enjoy, but when I picked up the frame and checked the fit and feel of everything on the Airborne I was just blown away. I can't wait to get it together.

The Sky Hag will weigh in at about 25 lbs when everything is said and done. That's factoring in about 3.2 lbs for the Surly fork. I'm curious how much the frame weighs by itself...

Okay, I'll shut up now! :D

Thanks again for the input everyone-

J.
 

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Discussion Starter · #12 ·
Here she is:


The pic is a little fuzzy... Took here out for a actual trail test run today. Love it, so far. Can't wait to get some more time under my belt with her.

Thanks for all the help and input!

J.
 

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Looks great! Most of the ones that were sold were black, but I really like the silver.
 
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