8/27/14 10:32 AM

I was looking for a fork for my Sirrus Adventure Bike.
Seems like for actual Specialized they where all aluminum. Also saw a Torker disc hybrid AL frame and that also had an AL fork.

Something I have always avoided is an AL fork. But these are pretty beefy looking disc forks that must be strong enough for the stresses of a disc setup. But begs the question, how potentially brutal might they feel on less than smooth surfaces? Or will the common 38C tires used on these negate said brutality?

8/27/14 10:36 AM

Having ridden a Cannondale pepperoni fork, I must ask," Do you like running a jackhammer" ?

Surely it's just a cost saving measure over carbon, right?

8/27/14 11:02 AM

We had a Cannondale MTB Tandem back in Joisey. Even with a 2.0 inverted tire I mostly remember getting my arms hammered. So I would certainly prefer steel over AL for that reason alone. Plus to keep the thing strong over the long haul, it would have to be way over built I am thinking and could be even worse than imagined??

8/27/14 11:54 AM

I have a Kona steel disc fork on my winter commuter. That thing is just as stiff and unrelenting as an AL pepperoni fork even with fat tires. Probably the stout, straight, and fat fork blades are just as influential as the material

David

8/27/14 9:20 PM

I tried both aluminum and carbon versions of the same fork on the same bike. Couldn't really tell a difference, but those were early days. Please don't laugh too hard at the photos:

Aluminum:


Carbon:

8/28/14 5:44 AM

Al frames and forks must be built to be very stiff, because unlike steel, Ti or carbon fiber, Al fatigues if it's allowed to flex significantly. That's why most Al frames are built to be very stiff and those that weren't (Alan, for one) tended to fail with age. Steel, Ti (very rare, but possible) and carbon forks can safely be built to flex significantly, making them much more comfortable. Taken to an extreme, you get forks like the Look HSC-1 which was a real noodle, but they held up just fine.

8/28/14 6:50 AM

I wonder if the advent of disc brake is going to make ALL types of forks ride stiffer. The needed extra material in the fork legs to support the caliper mounts and absorb the braking loads will make them heavier and, of course, stiffer.

8/28/14 7:13 AM

quote:

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I wonder if the advent of disc brake is going to make ALL types of forks ride stiffer. The needed extra material in the fork legs to support the caliper mounts and absorb the braking loads will make them heavier and, of course, stiffer.

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8/28/14 8:34 AM

If double disc brakes ever arrives, then the symmetrically-stressed fork should be able to be made a whole lot lighter and springier.

I don't really know if it's possible to scale down the parts sufficiently to get the overall weight down to where a single caliper and disc are, as there are scaling issues having to do with disc diameter which goes against a svelte design.

I like how Eric Buell attached the single brake rotor to the rim, but not sure how this could be implemented on a bicycle with lightweight wheels.
So I'm leaning toward advanced braking surfaces on the rim, together with hydraulic rim calipers, which I admit I have not tried.

8/28/14 9:15 AM

I understand the utility of hydraulics when we're talking about an automobile. But do hydraulic systems have any advantage for a bicycle other than at the margins? In other words, would hydraulic calipers be a momentous forward leap, or merely a small improvement>

8/28/14 10:47 AM

quote:

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I like how Eric Buell attached the single brake rotor to the rim, but not sure how this could be implemented on a bicycle with lightweight wheels.

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8/28/14 10:50 AM

bicycles already have a brake rotor at the rim.

I've pointed tat out over the pertinent threads as well. ;) Nice big disc they are too!

Had a Buell too. And I've also commented here before that it was the best brake my pinky ever had the pleasure to modulate. ;)

Back to the AL disc forks, perfect cheap solution given the overbuild to abate the paper clip syndrome. All about the revenue steam...

The old road AL forks one might assume [I do] the better the ride quality, the shorter the life span?

8/28/14 11:07 AM

I had some emails with Gunnar about an option they have for a Rohloff/disc compatible frame (steel). They indicated there would be some heavier tubing to accommodate the discs.

I had thought such a bike might be cool for long dirt/gravel rides. Then the thought occurred to me of getting a flat and changing a Rohloff rear wheel by the side of a dirt road in a rainstorm. Next...

8/28/14 12:39 PM

changing a Rohloff rear wheel


My klein with rear facing drop outs was bad enough.

You'd need a tubular on the Rohloff to really make it an enjoyable experience... ;)

8/28/14 4:15 PM

"Dumb question here...
I understand the utility of hydraulics when we're talking about an automobile. But do hydraulic systems have any advantage for a bicycle other than at the margins? In other words, would hydraulic calipers be a momentous forward leap, or merely a small improvement>"

Given the advancement in caliper leverage and cable tech over recent years, the hydraulic caliper wouldn't seem too significant or necessary.

But the feel of hydraulic actuation is quite superior to cables, with much firmer feel at the point of engagement and essentially zero friction.
The rider's inputs of increasing and decreasing braking force are much more real-time (i.e. quicker), in coordination with how traction is behaving, versus any kind of cable-operated brake.

Eliminating friction and cable elasticity is the key to accurate index shifting, and similarly it is the key to responsive braking that allows maximum stoppage with minimum lockup.

Having raced against CX riders who were using hydraulic disc brakes, I can say that they have more control entering corners while braking later, which makes their bike faster and more efficient overall.

8/28/14 4:24 PM

Read a CX article recently on discs. Seems the strongest point for them was not having to brake so early to wipe off the rims to get braking action. Thus faster in, faster out of corners. Main complaint was frying pad and discs in one race. But again, a lot faster to swap out the rotors and pads then to replace a rim or gamble on eating through one in the next heat.

8/28/14 6:05 PM

Point, counter point, question.

OK, over thinking it... We have a stronger leg on one side/leg. We have a dish on the front with a lessened brace angle on that same side...

Significance?

Even a steel fork with same blades with the added disc mount welded on, same with aluminum really?

8/28/14 7:45 PM

If a wheel is asymmetric, it will respond somewhat asymmetrically to loading.

I suspect this is of much lesser significance than the "steering" effect of one fork leg flexing differently than the other, which is the big problem with disc front brakes.

It seems to me that a good middle ground might be having a disc brake on the rear only, since during slick conditions the rear brake is the one that gets more of a workout.
The front brake could be an hydraulic rim caliper, while the rear brake would get hydraulic line replacing the long and contamination-prone (and thus friction- and elastic-prone) cable.

A disc-brake rear wheel could perhaps also have a carbon rim in this instance, providing a higher strength-to-weight ratio that is welcome in the rear.

In my own cx racing, I noticed that disc-equipped racers had much braking advantage even on dry dirt, or anywhere where traction might reach it's limits.

8/29/14 6:08 AM

...are:
"They're just meant to slow you down, not stop you"
"They're basically just a suggestion"

Canti's are so piss-poor in general, and especially in wet conditions, that it's no wonder that disks are a huge advantage for CX. MTBs abandoned canti's nearly 20 years ago for that reason. They also abandoned hydraulic caliper brakes (remember Magura calipers?), which were an intermediate step between canti's and disks. However, I can see hydraulic caliper brakes being a good option on road bikes for the reasons you cite.

I'd like to see hydraulic shifting too, but I wonder if there would be issues with such a system being temperature sensitive due to expansion and contraction of the fluid and the lines.

On a related topic, one concern I hear a lot about disk brakes for racing is the risk of being cut by a disk in a crash. It boggles my mind that manufacturers have yet to implement a very simple fix that would eliminate the problem altogether: round the edges of the rotors
This seems incredibly obvious, but nobody is doing it. Ideally, all of the edges of cutouts and supports would also be rounded. Yes, it would add to the time and cost to manufacture, but I don't think that it would be a hard sell for the few extra bucks involved.

8/29/14 7:46 AM

The other potential hazard I've heard mentioned for disc brakes is how hot the rotors get. In a crash, the rider or adjacent riders could be burned by contact with a very hot disc. Possible? Sure. Likely? Dunno.

8/29/14 5:08 PM

Actually, a lot of MTB riders have disc-burn scars that they managed to acquire without crashing.
It's about like all of the chainring tattoos that we've had to wipe off over the years, except that one pretty much has to be off of the bike to get a disc burn, and that you can't just wash it off.

These rotors get really hot, and don't cool off all that fast.

8/29/14 5:34 PM

I am picturing a road stage race with disc bikes. The mechanic wearing oven mitts when he hangs out of the car to mess with the bike while rolling...