Long question regarding fork for new project
#1
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 67
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Long question regarding fork for new project
Looking for suggestions and advice...
I'm currently building up a bike on a used steel frame I acquired. The frame requires a 1 1/8" straight steer tube and a 45mm rake. My hope is to convert this bike to a front hydraulic disc brake. There are several forks on the market for Cross bike frames, but they have a longer axel to crown length than this road bike's original fork had. (Forks with straight steerers and disc brake mounts that Ive seen have about 395mm axel to crown length... considerably longer than the stock fork which is approx 370mm axel to crown)
How much would the geometry of a frame (and likewise the way it handled)be altered if I were to install a fork that had approx 2.5cm longer axel to crown length? I suspect it would be considerable.
Secondly, since I don't really want to install a longer fork, does anyone know of a fork on the market that fits all of these requirements but that is not as long as the cross bike forks?
Sorry for the long and possibly confusing question. Hoping to hear some good news!
Stephen
I'm currently building up a bike on a used steel frame I acquired. The frame requires a 1 1/8" straight steer tube and a 45mm rake. My hope is to convert this bike to a front hydraulic disc brake. There are several forks on the market for Cross bike frames, but they have a longer axel to crown length than this road bike's original fork had. (Forks with straight steerers and disc brake mounts that Ive seen have about 395mm axel to crown length... considerably longer than the stock fork which is approx 370mm axel to crown)
How much would the geometry of a frame (and likewise the way it handled)be altered if I were to install a fork that had approx 2.5cm longer axel to crown length? I suspect it would be considerable.
Secondly, since I don't really want to install a longer fork, does anyone know of a fork on the market that fits all of these requirements but that is not as long as the cross bike forks?
Sorry for the long and possibly confusing question. Hoping to hear some good news!
Stephen
Last edited by sugarbaker; 06-20-16 at 09:28 PM.
#2
Senior Member
Join Date: Dec 2009
Location: Houston, TX
Posts: 28,682
Bikes: 1990 Romic Reynolds 531 custom build, Merlin Works CR Ti custom build, super light Workswell 066 custom build
Mentioned: 109 Post(s)
Tagged: 1 Thread(s)
Quoted: 6556 Post(s)
Likes: 0
Liked 58 Times
in
36 Posts
The resultant head tube angle would destroy your handling. Even a few mm change can be a problem. 25 is absurd.
Get in touch with a fork maker (Ritchey e.g. ) to learn what they may have for you that better meets your needs.
Get in touch with a fork maker (Ritchey e.g. ) to learn what they may have for you that better meets your needs.
#3
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,723
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5790 Post(s)
Liked 2,581 Times
in
1,431 Posts
So, let's do a bit of basic trig. If you sketch a frame, and draw a line from the rear axle to the lower head cup, you'd have an angle from the horizontal with a sine = 370/1000* or .370. Solve it for the angle and you get 22°. Raise the head by 25mm and the new sine = .395and the angle = slightly less than 23°. Since the frame is unchanged, you're talking about the head tube angle changing by a bit less than 1°.
This isn't insignificant, but it's not earthshaking either, and depending on how the bike handled before, may not be problematic a all.
I suspect you're finding the disc capable forks are taller is they are more likely to be made for CX vs. road use, and are taller to allow for greater tire clearance. With disc appearing on road bikes, I suspect you'll see disc ready road bike forks with tighter dimensions showing up soon enough, and you should fine one if you search carefully.
*assumes wheelbase of 40"/1000mm for easy math
This isn't insignificant, but it's not earthshaking either, and depending on how the bike handled before, may not be problematic a all.
I suspect you're finding the disc capable forks are taller is they are more likely to be made for CX vs. road use, and are taller to allow for greater tire clearance. With disc appearing on road bikes, I suspect you'll see disc ready road bike forks with tighter dimensions showing up soon enough, and you should fine one if you search carefully.
*assumes wheelbase of 40"/1000mm for easy math
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#4
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 67
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
there are disc forks on the market for the road bike frames... the problem being that all of them that I can find have a tapered steer tube that my frame won't accommodate. I have found one solution that is a Chinese carbon fork, but I prefer a known manufacture/branded fork as I don't particularly want to find out the limits of the Chinese model while I'm descending at 45mph.
I suspect the solution to my problem will be to settle for rim brakes, but I will keep searching and send some inquires to a few manufactures.
I suspect the solution to my problem will be to settle for rim brakes, but I will keep searching and send some inquires to a few manufactures.
#5
Senior Member
Join Date: Jan 2011
Location: Lewisburg, TN
Posts: 1,356
Bikes: Mikkelsen custom steel, Santa Cruz Chameleon SS, old trek trainer bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Likes: 0
Liked 6 Times
in
4 Posts
I agree with what was said previously regarding contacting a custom frame maker, they should be able to whip up an appropriate fork. May not be the cheapest, but it'll work!
#6
Senior Member
Join Date: Apr 2009
Location: New Rochelle, NY
Posts: 38,723
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Mentioned: 140 Post(s)
Tagged: 1 Thread(s)
Quoted: 5790 Post(s)
Liked 2,581 Times
in
1,431 Posts
The problem with the custom builder approach is that so many don't build forks anymore. One that does, and does good work at not outrageous prices is Chris Igleheart. If you want to explore a built to spec fork he might be the place to start. If you do call Chris, please give him my regards.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#9
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 67
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Pulled the trigger on a chinese fork that fits the requirements for my build. $88 included the shipping and it will give me a first hand inspection. I will give it a go because I like the style and the cost. Should the fork not work out, I'll either go to one of the custom builders, woundup composites or I'll switch to rim brake in front (I'll be using a rim brake in back, so if my test fails, it won't be a noticeable detriment)
#11
Senior Member
Pulled the trigger on a chinese fork that fits the requirements for my build. $88 included the shipping and it will give me a first hand inspection. I will give it a go because I like the style and the cost. Should the fork not work out, I'll either go to one of the custom builders, woundup composites or I'll switch to rim brake in front (I'll be using a rim brake in back, so if my test fails, it won't be a noticeable detriment)
#12
Senior Member
Thread Starter
Join Date: Apr 2008
Posts: 67
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 16 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
here is the exact auction. The seller states there is only 1 left of the original 10. I have seen other auctions for the same (I assume) fork, but this seller is the only one that specified the fork offset (45mm) and the axle to crown length (370mm). If you search eBay or other known sites that sell these Chinese forks, search for "carbon disc road fork" and a handful of options will show up among the results. When I receive the fork sometime late in July or early August, I will post pictures of the unboxing, and some hi-res detailed pics of the fork I receive. Stay tuned.
New 3K Carbon Fork Rigid Straight Disc Brake 700c Road Bike Fixed Gear 1 1 8" | eBay
New 3K Carbon Fork Rigid Straight Disc Brake 700c Road Bike Fixed Gear 1 1 8" | eBay