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  1. #1
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    Sub 800 gram 26" custom chromoly fork ?

    I've got a filet brazed custom steel frame. Had it since 1998.

    I started out with a 63mm Manitou Mach 5, and then replaced it with a Tange Big Fork which was super stiff, so I got an Origin 8 carbon fork instead. The carbon fork rides well, but I don't trust it entirely.

    I am 6'4, 225 lbs and am an aggressive xc rider. I'd like to get a custom chromoly fork at some point, or perhaps even titanium. Steel is more likely at my price point though.


    Here's a look at the bike. With the original suspension fork, the head angle was 71.5 degrees and the seat angle was 74 degrees. When I put on the (much shorter) Tange Big Fork to get rid of the aging Manitou, the angles went to 74/74.5. The Origin fork is a bit taller. Although I haven't measured it, I think the head angle is probably like 70 degrees right now. If I were to go custom, I would probably want end up with 72/74 degree angles on a fork that's as light/compliant as possible for my size and riding style.

    For your framebuilders out there with some experience building steel forks, is a sub 800 gram mtn fork doable ? The steerer tube would need to be 300mm to fit my frame. I'd probably want a suspension style box crown and curved legs, something along the lines of the Ritchey biplane crown that came on my 1993 Bridgestone MB1.
    Attached Thumbnails Attached Thumbnails Sub 800 gram 26" custom chromoly fork ?-dsc02064.jpg  


  2. #2
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    Ha!

    Big guy
    +
    "Aggressive" rider
    +
    Low budget
    +
    Picky about getting a specific look
    +
    Wants something super light
    =
    Disaster

    The answer, in case you hadn't already figured it out, is no. Raise your budget and get a ti or carbon fork if there is a magical number of grams that will make you happy. Alternately forget the weight requirement and get exactly what you want in steel.

    -Walt

    Quote Originally Posted by phoenixbikes View Post
    I am 6'4, 225 lbs and am an aggressive xc rider. I'd like to get a custom chromoly fork at some point, or perhaps even titanium. Steel is more likely at my price point though.
    Waltworks Custom Bicycles
    Park City, UT USA
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  3. #3
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    Also, curved legs with disc are almost surely asking for disaster. With the change in the location of the braking force, most custom forks that are designed to have a good feel will end up "uncurving" from the brake force.

    I am also having a hard time making the geometry numbers you have posted work out. The HTA and STA should change in a more linear fashion with each other, if I'm not mistaken.

  4. #4
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    Quote Originally Posted by Francis Buxton View Post
    I am also having a hard time making the geometry numbers you have posted work out. The HTA and STA should change in a more linear fashion with each other, if I'm not mistaken.
    You are correct. If a different fork length changes the HTA by 1 (or 2 or 3) degree(s), the STA also changes by the same amount.
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  5. #5
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    Given what I know already, it is entirely possible. I thought I'd ask here to get the opinions of other builders but perhaps that was a waste of time. In any case....

    Walt, you must have missed this in my 1st post, or you didn't look at the picture. I HAVE a carbon fork on there, already. If I were to go chromoly, I wouldn't want to do so unless the weight is about equal. I think the carbon fork I have on the bike right now is about 770 grams. The Tange Big Fork I had was about 900 grams. I have a KHS steel fork on another bike that is also almost that light, so I think 800 grams might actually be realistic. I didn't arrive at that 'magic' 800 gram figure through pure ignorance or stupidity. Although it might appear that I am an idiot I DO in fact have some understanding of fabrication having designed a few frames and worked in a machine shop myself.


    My budget is not really 'low' for what I am after either. I can probably afford about $350 for a fork. The original builder of the frame will do one for about 250 so I think my budget is probably realistic, if not um, perfectly adequate.

    Francis,
    probably not after a disc fork for this bike. Rim brakes would do just fine, so I think curved legs are still an option. The only reason there is a disc brake in this picture is because the fork is carbon and I was not running rim brakes at the time I took this picture. That has changed recently.
    Last edited by phoenixbikes; 02-04-2013 at 12:53 PM.

  6. #6
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    Have your guy do it, then...

    Having built something like 600 forks (and having built some that were too light and came apart early on when I was trying to do the kind of thing you are asking for) I would not do what you want. If you find someone that will, more power to you. Pay up your dental insurance.

    Apologies for the snark, but it's funny to me that someone who weighs 225 pounds and is riding a 15 year old fillet brazed steel frame is obsessed with having a fork that is lighter than some arbitrary number of grams.

    -Walt

    Quote Originally Posted by phoenixbikes View Post
    My budget is not really 'low' what I am after. I can probably afford about $350 for a fork. The original builder of the frame will do one for about 250 so I think my budget is probably realistic, if not um, perfectly adequate.
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  7. #7
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    Well....

    This is my 'weight weenie' bike. It's currently about 27.5 lbs. I am thinking about a new fork, but it's not really worth it unless the fork is under a certain number of grams. Spending money to ADD weight to this bike is not in the cards. Seems like that might be a very easy thing to understand....

  8. #8
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    I really don't know what to say...if this is a troll, ya got me. If it's not, wow.

    -Walt
    Waltworks Custom Bicycles
    Park City, UT USA
    www.waltworks.com
    waltworks.blogspot.com

  9. #9
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    Re: Sub 800 gram 26" custom chromoly fork ?

    Im guessing troll.

  10. #10
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    No I am not a troll. I am in fact a fairly nice guy. I do things like stopping to help a rider straighten his front wheel after it's been tacoed, and slowing to a walking pace when I pass hikers, etc. But I do stand up for myself when people are needlessly smug, and when I feel like I need to.

  11. #11
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    Sub 800 gram 26" custom chromoly fork ?

    Quote Originally Posted by phoenixbikes View Post
    No I am not a troll. I am in fact a fairly nice guy. I do things like stopping to help a rider straighten his front wheel after it's been tacoed, and slowing to a walking pace when I pass hikers, etc. But I do stand up for myself when people are needlessly smug, and when I feel like I need to.
    Walt is just warning against holding onto unrealistic expectations.
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  12. #12
    WIGGLER
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    I just did a quick search at Nova's web site and a chromoly steer tube is .85lbs and
    a pair of unicrown fork legs are 1.60lbs and you'll need drops and a brake tab so Im
    guessing 3lbs is more realistic for a chromoly fork.
    PAYASO 36er.....Live the Circus

  13. #13
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    OK

    Lets cool this down a little.

    How about adding some fact to get a more acurate perspective.

    Looking at my note book of data collected on my own bikes, I had a Tange SuperLight fork with 200mm steerer tube to suit a 26" wheel, suspension corrected @ 832gr, V-brake Studs.


    I currently run a Nova Cycles MTB Unicrown fork blade with 200mm Steerer with a shorter A/C and disc tab @830gr.

    I use my bike mostly as an all-rounder Road-gravel-single track. It does not see 'air' and I weigh in at 183lbs, bike weighs 22lbs.

    I would not go lighter in construction with steel.

    Your requirement of a 300mm steerer has blown the equation and a final 900gr in your case is realistic.

    Also, though not to aggravate your query, 27.5lbs is well off 'light', I consider 22lbs a starting point for a less dedicated weight weenie, on a fully geared bike for XC. Most manufactured 29'er bikes are around that weight of 27-28lbs. What will 100gr do for a portly bike?

    Eric
    If I don't make an attempt, how will I know if it will work?

  14. #14
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    OK, here's a data point so you don't think we're picking on you:

    1 1/8 standard TT steerer ~240mm
    Bob Brown twin plate crown
    Heaviest TT fork legs, raked
    425 a-c

    980g

  15. #15
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    Quote Originally Posted by phoenixbikes View Post

    This is my 'weight weenie' bike. It's currently about 27.5 lbs.
    Holy Cow! How much do your heavy bikes weigh?

    Anyway, comparing an aluminum steerer with steel is silly. That Black Ops fork is pretty light for what it is already so you won't go lighter. I rode my Black Ops fork once or twice and got rid of it. I couldn't deal with the chatter under braking because the thing was too noodly for my liking. The steel fork added a pound I'd bet but at least I could brake as hard as I wanted and not have the front end chatter out from under me. I'll carry an extra 1lb in bike to have it perform correctly--you're already carrying an extra 6ish lbs on that one so what's another 200-400 grams?

  16. #16
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    Every single part on this bike is hand picked because they are light. At a certain point, saying 'what's another 100 grams' with multiple parts adds up to a heavy bike. I have gotten it down to 26 pounds in the past, by being careful about my parts selections. The dropper post is what makes the bike over 27 pounds. It's the exception to the rest of the light parts I have on that bike. The frame is a 21", so getting it down to 22 lbs is just not going to happen.

  17. #17
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    Quote Originally Posted by phoenixbikes View Post
    Every single part on this bike is hand picked because they are light.
    For a light weight bike a carbon fork is the way to go. Good carbon forks have better strength to weight ratio then steel. The same is true for frames and all the parts of the bike. Basically if you try to build with steel at the same weight as carbon the bike will be a lot weaker.

    Steel is a great material for ride quality and customization but it sounds like your focus is on weight and as such carbon is your best bet.
    Mark Farnsworth, Raleigh, NC
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  18. #18
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    A Theoretical Exercise - Fork

    Phoenixbikes, I must apologise to you re: weight. I was hoping to draw attention away from the fork to the over-all bigger picture of your situation, not to expose you so you feel defensive.

    I have looked a little further at the fork, as for me, I am investigating variations of build so I have some figures to work with.

    Steerer Tube - butted 300mm x 2.0/1.55mm = 378gr
    Blades, MTB unicrown for 400mm AC = 436gr
    Drop-outs 14mm plug in, no eyelets = 50gr
    Brake mounts - V brake = 34gr

    Total = 898gr

    The steerer is fixed weight, I would not go lighter for a rider of your size. Many would suggest using the thicker butt steerer for you.

    If you were to use the only variable available to you that is changeable - the fork blade - and use a CX blade, and we are treading on very questionable ground here, DEDA CX blade @ 356gr gives you a total build of 818gr. This is NOT a BUILD YOU should be looking at.

    If you were to use a Plate crown with TT 1.0/.7, also light for you, will yeild a heavier fork as described by Dr Welby.

    TT Fork blades @ 428gr un-cut plus plates. Unicrown will give the lightest builds.

    Walt is correct in saying NO GO. He has experience to back up his statement.

    Now, looking at your bike. XC racing. Rigid Fork.

    I assume that the terrain you ride on is not too demanding that you need suspension - rigid fork.
    The cockpit area is not one I suggest you tamper with - saddle, bars etc.
    It is more important that you are comfortable, so whether light or heavy, this is your personal choice area.

    The frame appears to have a long top tube and an unusual seat tube. They are likely to be heavier gauged and add to the overall weight of your bike.

    I would suggest that you examine the wheel weights and the weight of the bike less wheels and see what is happening.

    As a reference point for you, I had a 1992 Marin Muirwood 19" that I started riding on @ 28.25lbs.

    The frame weighed 2678g, the fork - 920g. Swapped the fork for a Tange Superlight - 832g. Not much gain. Looked at the wheels and eventually replaced them along with the rubber I was riding, and reduced from 4325g for the pair complete as you ride them, down to 3328g. Over 2lbs gone.
    I did an appraisal of what was left and managed to get down to 24.5lbs.

    It is my hope that you will evaluate your needs in the big picture. It may be time to move on and build up a new or newer set-up that you can get competitive on and kick some dirt. Getting light steel forks really is a bit risky. The carbon forks appear to be performing well, at least we're not getting bad reviews in this forum, but thats not quite what we are about.

    Eric
    If I don't make an attempt, how will I know if it will work?

  19. #19
    DWF
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    29er fork, 420'ish axle to crown, Columbus Max unicrown blades, one disc brake hose guide, Pargon Spike disc brake mount, Paragon crown race, lightened 3/4" plug style fork ends, 310mm long 1.125" steerer tube = 1,063 grams

    Same fork but with TT lightweight 1.125" steerer cut to 250mm = 963 grams.

    It's steel, it's designed for disc brakes, it's not going to be as light as CF. Just accept your enormity and seek bike parts that are the same percentage of your weight that those narrow assed 130-pounders deal with.
    A man must have enemies and places he is not welcome. In the end we are not only defined by our friends but those against us.

  20. #20
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    Quote Originally Posted by Eric Malcolm View Post
    Also, though not to aggravate your query, 27.5lbs is well off 'light', I consider 22lbs a starting point for a less dedicated weight weenie, on a fully geared bike for XC. Most manufactured 29'er bikes are around that weight of 27-28lbs. What will 100gr do for a portly bike?
    That was my point too. My 19" frame 29er bike front and rear suspension with disc brakes and a Brooks saddle that weighs almost what a dropper post would weigh comes in at a 27.5lbs on the scale. Poenixbik, no offense here, but just get a fork off the shelf and ride it. There is nothing light about this bike and the fork weight certainly isn't going to make that much of a difference on this particular sled.

  21. #21
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    I already have a fork off the shelf, I am not really looking for another one. That wasn't the point of the thread. The point of the thread was to ask if it's possible to build a sub 800 gram chromoly fork, that would work for me. The builder who originally made the frame seemed to think it was pretty doable, but I gained 50+ pounds and grew an inch and a quarter since I got the bike. Think I'll just keep the carbon fork I have now and when it needs to be replaced, I'll cross that bridge when I come to it. Maybe at that point I'll have the budget for a ti fork and forgo the custom chromoly option.

  22. #22
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    Quote Originally Posted by DWF View Post
    Just accept your enormity and seek bike parts that are the same percentage of your weight that those narrow assed 130-pounders deal with.
    75% of the time I spend on any of my bikes (24"/26"/27.5" and 29", and two 650b6ers) is spent going UPHILL. The other 25% of my riding is technical xc with a few 1500-3000 ft descents thrown in. For the type of riding I do, it makes sense to go as light as safely possible. I try to avoid pedaling 35 pound bikes if I can help it and I can by going for the lightest parts I can find that hold up.

  23. #23
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    I think we're done here huh, Walt?

  24. #24
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    Dude the frame building forum can be kind of snarky sometimes, yeah.

    But WTF. I think you need a suspension fork instead of weight, uh, "savings".

    27 pounds is considered light for a fat tire bike, and those are pushing around several pounds of extra wheel weight.
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  25. #25
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    Hey;

    The Salsa Enabler fork I use on my Fatbikes is one of the stouter bits out there as far as I know. 1176 grams of rockin steel. Not even a pound more than you are looking at. It flexes A LOT under me (240lbs), enough to make me a little uneasy at times. They offer no rotor restrictions that I could find. I run a 8". I can't imagine going lighter, but we likely don't ride the same either.

    Always remember, in such instances, physics, Murphy, and Darwin always win.
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