Fork Support

[user 35233]

I'm considering suspension forks and wondered if 28" tires would clear forks listed as 27.5" or 26". All my bikes came with forks and seemed to have ample room regardless of the frame size so I've never worried. Do fork manufacturers list these as safe heights allowing space for fenders or maybe caliper positioning?

 

[ingola]

Should fit

 

[user 35233]

Thanks. I know its a noob question but I'm combing over obscure parts without measurements so I just wondered if there was a standard spacing. I've gathered through measuring different size forks that theres a fairly standard 1.5 inch clearance.

 

[user 35233]

Does anyone know what this "suspension" is called and whether thats just rubber resistance or a cover over a shock absorber? I'm wondering if I can make it myself or replace it with a spring, whether tension or decorative. I'm told there are technical issues with these types of suspensions which is why they aren't prevalent in the U.S.(?)

 

[RustySprockets]

Cannondale Headshok, no? I've never actually worked on one.

 

[user 35233]

Cannondale Headshok, no? I've never actually worked on one.

That triggers a memory now that you mention it. Sounds right. I find them labeled "dutch" and "trekking" most often appearing on ebayUK but not US. I see other straight forks with similar neckwear that have screws hidden beneath a hood but this one looks solid.

 

[Starnger]

This is called monoshock fork. Cannondale Headshock was a first mass marketed product of this kind. Depends on a particular design you may or may not be able to replace the spring yourself. I've used a fork like that to build a custom fork for my electric bike build.
Here is the beginning of the build and here is a continuation.

 

[user 35233]

This is called monoshock fork. Cannondale Headshock was a first mass marketed product of this kind. Depends on a particular design you may or may not be able to replace the spring yourself. I've used a fork like that to build a custom fork for my electric bike build.
Here is the beginning of the build and here is a continuation.

Thank you! That all helped tremendously.

 

[Son of Kradus]

Extend the drop outs on the forks, you will get a bigger wheel to fit! I made a 29' wheel fit in a 26" fork set!, looks great too!

 

[Starnger]

Thank you! That all helped tremendously.

Just one detail - the fork on your photo is aluminium. Would be hard to weld on to. The one i used is steel, and in general steel ones are a bit less common.

 

[user 35233]

Just one detail - the fork on your photo is aluminium. Would be hard to weld on to. The one i used is steel, and in general steel ones are a bit less common.

Is there room for me to cut the steerer above those welds in the middle where I'm guessing the shock absorber is attached?

This is the best detail I could find on a different model. This looks pneumatic, yours looked like a coil spring, correct? But both have 4 dimples from what looks like added tube? I imagine you'd mount the shock into that cuff first then drop it in and connect it? Was there room to lose atop yours?

 

[Starnger]

Is there room for me to cut the steerer above those welds in the middle where I'm guessing the shock absorber is attached? View attachment 227715
This is the best detail I could find on a different model. This looks pneumatic, yours looked like a coil spring, correct? But both have 4 dimples from what looks like added tube? I imagine you'd mount the shock into that cuff first then drop it in and connect it? Was there room to lose atop yours?View attachment 227716

There is some room, though not much. Basically you can cut to the depth you can fit your finger in. In my case it was about an inch or two of the thread, but i didn't even cut the whole thread off, and definitely the cut is far away from the weld you see. Remember you still have to leave some space for the star nut to sit in in case if you want to switch to ahead headset, or otherwise weld some nut in. In case you want to stay with threaded headset you are probably limited with the depth of the steerer needed to put the quill stem in safely.

 

[user 35233]

https://ratrodbikes.com/threads/splat-rat.114837/post-1196042That cup in a cup was an elegant solution I'd been seeking. Did you ever do anything with that single spring on the steerer @Wildcat? I imagine there was a bit of unwanted bounce up front. I'm trying to figure out front suspension for skinny 28" wheels. Most slimmer fork options are too short and when long, too wide and chunky, so that would be my ideal config. Most springers I see are 26" and the only listing I've found labeled 29" (attached) is twice the price. As it's the only one I'm also wondering if it's just a 26 and they all clear 28s. Also wondering if these are going to fail on me. they look flimsy, I've broken better.

 

[Wildcat]

https://ratrodbikes.com/threads/splat-rat.114837/post-1196042That cup in a cup was an elegant solution I'd been seeking. Did you ever do anything with that single spring on the steerer @Wildcat? I imagine there was a bit of unwanted bounce up front. I'm trying to figure out front suspension for skinny 28" wheels. Most slimmer fork options are too short and when long, too wide and chunky, so that would be my ideal config. Most springers I see are 26" and the only listing I've found labeled 29" (attached) is twice the price. As it's the only one I'm also wondering if it's just a 26 and they all clear 28s. Also wondering if these are going to fail on me. they look flimsy I've broken better.

I didn't wind up using a single spring on a fork tube. It wound up looking like a Monark springer with 2 springs.

The chrome springers like the one you posted are somewhat flimsy. At about 4" wide wouldn't look right with a skinny tire. I have 2 of them and they are good, but not as durable as a standard fork. While they may not break, they have a lot of flex and are bouncy. If your tire is 622, it's 63mm taller than a 559 (26 x 1.75) tire. From the axle to fork crown is 32mm (1.25 inches) taller. If there's that much extra space in the fork then it would work as long as the tire doesn't move upward with the springer. A brake may not fit in the smaller space. So a 26" fork may work for you.
Also, If you make your own it will be heavy. I would go with the skinny fork shown above in your post.

 

[ingola]

https://ratrodbikes.com/threads/splat-rat.114837/post-1196042That cup in a cup was an elegant solution I'd been seeking. Did you ever do anything with that single spring on the steerer @Wildcat? I imagine there was a bit of unwanted bounce up front. I'm trying to figure out front suspension for skinny 28" wheels. Most slimmer fork options are too short and when long, too wide and chunky, so that would be my ideal config. Most springers I see are 26" and the only listing I've found labeled 29" (attached) is twice the price. As it's the only one I'm also wondering if it's just a 26 and they all clear 28s. Also wondering if these are going to fail on me. they look flimsy, I've broken better.

Schwinn made a repop Springer that will fit a 28 skinny tire really well. I've found them on eBay from time to time

 

[ingola]

28 in there skinny

 

[rickpaulos]

I had a ~2000 Cannondale F500 (and a couple others) with the head shock so I learned all about them. The rubber boot is suppose to keep water and crud out but it works far better at keeping the water in so it got very rusty and seized up (before I bought it) I found out the castle nut tool was $100 to take it apart. And there are no parts so why bother. I sprayed a lot of wd40 in and it finally broke loose and I sold the bike. Cannondale had some 30 different versions of head shocks and another 30 versions of the Lefty. They used many technologies inside that you can't see. Air, elastomer or metal springs, and a variety of dampening methods. And then they dropped the entire concept. Owners of vintage Cannondale can buy head tube reducers so standard forks and headsets can be installed on the older models with the oversize head tubes.

The head shock fork has a square inner steerer tube attached to the fork crown. The outer steering tube is round on the outside and square on the inside. there are 4 strips of needle bearings in between (front, back, left, right). they sold replacement bearings in a number of needle sizes, about .001' from one size to the next. If the flat surfaces wore, you could put in oversize bearings to take out the slop.

Don't ever let a Head Shock fork get wet. Don't store it in cold place where daily temp swings can cause condensation in the bike.

There have been other in line springer/shock forks (Moulton in the 1960s) and Trek in the past few years. Surely there were other obscure bike models that had them. No surprise about Moulton. The Brit engineer that designed the suspension for the Mini went on to design small wheel bikes with suspension that worked. Decades before Cannondale ever made bikes.
https://www.minisport.com/blog/dr-alex-moulton-mini-suspension-timeline/


The white fork in the photos looks more like a newer Trek hybrid fork. hydraulic disc brake compatible.