Lightweight steel disc fork options

[Erik]

I'm working on a new ti 650bx48c/27.5x2.1" frame and looking for a lightweight fork to use with it. 395mm length with 50mm or more offset, straight 1 1/8th steerer, standard 9mm qr axle and for use with disc brakes. I have searched for it but I'm not really seeing anything in a production fork. The closest is the Salsa Vaya and the SOMA Wolverine fork (2.4lbs) which is available separately now and the SOMA all road carbon (less that 2 lbs). Almost all carbon forks are 45mm offset but the SOMA carbon is 50mm. Anything out there I am missing? The next step is custom which is not a problem but the available fork blades are thick and heavy to deal with the disc stresses. Is there a way to have it all? A lightweight, flexy bump eating steel fork with a disc that weights 1.5 lbs? Alex how much did your commuter fork weigh and what blades did you use?
Thanks, Erik in Portland

[Jambi Ganbar]

You are missing on the awesome and affordable fork from Rodeo Labs.

http://www.rodeo-labs.com/rodeospork/

Everything you need for a great price.

Jambi

On Fri, Jan 20, 2017 at 3:51 PM, Erik <threa...@gmail.com> wrote:

I'm working on a new ti 650bx48c/27.5x2.1" frame and looking for a lightweight fork to use with it. 395mm length with 50mm or more offset, straight 1 1/8th steerer, standard 9mm qr axle and for use with disc brakes. I have searched for it but I'm not really seeing anything in a production fork. The closest is the Salsa Vaya and the SOMA Wolverine fork (2.4lbs) which is available separately now and the SOMA all road carbon (less that 2 lbs). Almost all carbon forks are 45mm offset but the SOMA carbon is 50mm. Anything out there I am missing? The next step is custom which is not a problem but the available fork blades are thick and heavy to deal with the disc stresses. Is there a way to have it all? A lightweight, flexy bump eating steel fork with a disc that weights 1.5 lbs? Alex how much did your commuter fork weigh and what blades did you use?
Thanks, Erik in Portland

--
You received this message because you are subscribed to the Google Groups "650b" group.
To unsubscribe from this group and stop receiving emails from it, send an email to 650b+unsubscribe@googlegroups.com.
To post to this group, send email to 65...@googlegroups.com.
Visit this group at https://groups.google.com/group/650b.
For more options, visit https://groups.google.com/d/optout.

[Justin Hughes]

Tapered steerer on the Spork. And damn if it isn't one of the ugliest forks I've ever seen. 

I looked at all options a few months ago. You want a 680g steel disc fork? I think you'd have a hard time finding a builder that would be comfortable building a disc fork that light if it's even possible. The Vaya fork is available in 50mm rake and it's cheap, but A-C is 405mm so if your bike was designed for 395mm it will slacken your angles and raise BB slightly. 

Justin

On Friday, January 20, 2017 at 9:53:45 AM UTC-5, Jambi Ganbar wrote:

You are missing on the awesome and affordable fork from Rodeo Labs.

http://www.rodeo-labs.com/rodeospork/

Everything you need for a great price.

Jambi

On Fri, Jan 20, 2017 at 3:51 PM, Erik <threa...@gmail.com> wrote:

I'm working on a new ti 650bx48c/27.5x2.1" frame and looking for a lightweight fork to use with it. 395mm length with 50mm or more offset, straight 1 1/8th steerer, standard 9mm qr axle and for use with disc brakes. I have searched for it but I'm not really seeing anything in a production fork. The closest is the Salsa Vaya and the SOMA Wolverine fork (2.4lbs) which is available separately now and the SOMA all road carbon (less that 2 lbs). Almost all carbon forks are 45mm offset but the SOMA carbon is 50mm. Anything out there I am missing? The next step is custom which is not a problem but the available fork blades are thick and heavy to deal with the disc stresses. Is there a way to have it all? A lightweight, flexy bump eating steel fork with a disc that weights 1.5 lbs? Alex how much did your commuter fork weigh and what blades did you use?
Thanks, Erik in Portland

--
You received this message because you are subscribed to the Google Groups "650b" group.

To unsubscribe from this group and stop receiving emails from it, send an email to 650b+uns...@googlegroups.com.

[Cary Weitzman]

Erik

January 20, 2017 at 9:51 AM

I'm working on a new ti 650bx48c/27.5x2.1" frame and looking for a lightweight fork to use with it. 395mm length with 50mm or more offset, straight 1 1/8th steerer, standard 9mm qr axle and for use with disc brakes. I have searched for it but I'm not really seeing anything in a production fork. The closest is the Salsa Vaya and the SOMA Wolverine fork (2.4lbs) which is available separately now and the SOMA all road carbon (less that 2 lbs). Almost all carbon forks are 45mm offset but the SOMA carbon is 50mm. Anything out there I am missing? The next step is custom which is not a problem but the available fork blades are thick and heavy to deal with the disc stresses. Is there a way to have it all? A lightweight, flexy bump eating steel fork with a disc that weights 1.5 lbs? Alex how much did your commuter fork weigh and what blades did you use?
Thanks, Erik in Portland

Although Columbus doesn't show it on their web site, they make a version of the carbon Tusk Trekking fork for discs with fender mounts and mid-fork eyelets and a 50mm offset. I've actually handled it and fit a wheel with a well worn-in Grand Bois Hetre, plenty of clearance for that tire and fenders (although I didn't actually measure the offset, so I can't state that it truly has a 50mm offset).

Available here in Canada through Marinoni, I believe.

Cary

[HillDancer]

In carbon, 3T Luteus II is 50mm offset, 395 A/C, but has tapered steer tube.  New Luteus versions are thru-axle; former version for QR is still available via deep web search.  Whisky No.7 QR CX has straight steer tube, 47mm offset, 393 A/C, and clearance for 55mm 650b tires with room to spare.

In off-the-shelf steel, a Surly Disc Trucker for 700c is almost close to what you're looking for, but not lightweight.

[actual...@gmail.com]

Erik, You can look at my solutions here...

https://www.flickr.com/photos/44613580@N03/10065998466/

I have been developing my road/cross specific truss fork for years now and am about ready to begin production. The one I linked to is an early type. The current forks are more refined. 15mm through axle, Aluminum removable steer tube, larger distance between the crown and truss at the triangulation point. I have eliminated the curve portion at the top in favor of a straight section which makes things stiffer. 

good luck in your search. 

hale, Pleasant Hil, CA

[njh...@gmail.com]

If that's the sort of fork you want, probably better to stick with rim brakes. I had Steve Hampsten make me a Ti 650b custom a few years ago and he made a nice steel fork with stainless steel dropouts to go with it. I never weighed the fork on its own, but it was pretty light. I don't think anyone will make you a light steel disc fork - too much chance of the left-hand fork blade bending back in an emergency stop

[Philip Kim]

i am more intrigued by the truss fork option on road bikes. not used to the look, but it does look elegant in its own right. 

would be interested in knowing if it would be lighter than a "regular disc fork" and by how much.

[Tom]

The truss fork looks quite elegant. However, regarding "I have eliminated the curve portion at the top in favor of a straight section which makes things stiffer," I think many on this forum are looking for a steel disc-compatible fork that's less stiff. Was your original design so flexible as to cause handling issues?

-tom

[satanas]

I'm not so sure "almost no flex during heavy braking" is actually desirable unless you're a paranoid mountain biker and unused to seeing forks flex. We had a customer like that once who was convinced his Columbus SL forks would snap; we ended up selling him a Max frameset and he was happy, but I thought the original was nicer.

Stiffer helps steering precision, but not ride comfort, so I guess it depends what the individual cares about. It does look "interesting," another two-edged sword/conversation starter.

Later,
Stephen

[Justin Hughes]

I gotta say I'm intrigued. My current steel disc fork does everything I need it to, but I dig the idea and even the aesthetic of a truss fork with skinny tubes. Though, it could look a bit incongruous with a lugged frame. 

And I still have yet to see any evidence that says a 2" or larger tire at 30psi or lower allows any meaningful or perceptible "shock absorption" or "compliance" from a steel fork. If it does, then it stands to reason to me that the fork flexy in an undesirable way. 

Justin

[Stephen Poole]

On 11 Oct 2017 1:07 pm, "Justin Hughes" <justin...@me.com> wrote:

And I still have yet to see any evidence that says a 2" or larger tire at 30psi or lower allows any meaningful or perceptible "shock absorption" or "compliance" from a steel fork. If it does, then it stands to reason to me that the fork flexy in an undesirable way.

^ BQ seems to have a different opinion.

As devil's advocate, I've not seen evidence to say a wide, low pressure tyre prevents the fork flexing, though certainly the tyre will deflect first. I imagine this is true regardless of fork material, i.e., the tyre would still deflect first if one's fork was made of carbon, alu, wood, etc, unless it was seriously underbuilt or included suspension. (Or the tyre pressure was extremely high.)

Presumably, the tyre and wheel must still transfer at least some loads to the headset, frame and handlebars; the forces are not totally isolated until or unless the tyre bottoms out. These forces could potentially flex the fork, assuming it was designed and constructed so that was possible, for example with raked steel forks of light enough gauge and cross section. Straight carbon forks aren't intended to flex much (and don't IME), but could still provide some vibration damping metal forks do not. I've no idea how large or small such effects might be, but they do exist. And stiffness always helps steering precision, provided the tyre doesn't lose grip. Stiffness doesn't do anything for comfort when braking on rough descents offroad though; 42mm tyres don't do enough either, and I'm not sure what size tyre - if any - would help. Probably not anything that would fit through most forks, though 60-100+ mm might do the trick.  :-(

One advantage of truss forks is that it's simpler to attach bags to them directly, no rack required; Jones sells bags that do this.

Later,

Stephen

[Justin Hughes]

Yes, this is my thinking. I don't mean to say nothing is transmitted past the tire until it bottoms out. That's why I used the terms meaningful and perceptible. Though, admittedly, those aren't fixed variables/concepts. 

Your point about stiffness and handling is right on. Ask someone who has given a fair shake to similar bikes with QR forks and thru axles on the kind of riding where steering precision and responsiveness are desireable/needed and I suspect they are glad to have the thru axles. 

Justin