deuce808

I have an idea to use a sram s80 with its road hub on a fixed gear. before you jump all over me on this please read the entire post. i am looking for anyone else that has had this same thoughts or someone who has tried it. i know there are other ways of doing it. but i like to think outside of the box. if the theory is flawed please explain why, if you have thought about what else i may try then feel free to comment.

1. Lock up the pawls using either hard plastic or metal shims. Place behind the pawl where the leaf spring would be. Would this be sufficient? I did a test run and it does keep the hub from freewheeling.

2. Using the s80s oversized axles so I wouldn't need to change bearings. I would need to cut down to a appropriate width. I'm thinking 2mm inside of the outter bearing on each side, then drill out the center (because its stepped down for a skewer) to allow a normal threaded track axle to slide through. Cone nuts would be used on either end to tension correctly and spacers will be used to make up any difference.

3. Cassette spacers and a splined track cog would be used to complete the set up.

In theory this would be used to allow for the beautiful wide blades spokes and sram hub to be retained while allowing use as a fixed gear wheel. Any feedback or suggestions. I know I can just lace it to a philwood and be done but I'm thinking that since this is reversible (with a replacement axle) then it would allow me to run it on a road bike later if need arises. Anyone think it will hold up? The shims in the hub? I don't skid aside from hop skids at sub 20mph speeds and run a brake if that helps.

Please let me know. Pondering about trying this while waiting on a philwood hub.

Thanks

surreal

It should be possible, but not reliable. I'd worry that the shims would break under load. In the meantime, ponder these fun products, while you freewheel around and await your Phil:
1- overpriced hub that is designed to achieve the same effect https://www.sram.com/sram/urban/produ...ngle-speed-hub
2- overpriced gizmo intended to essentially do what you've described by removing the freehub body and associated pawls from a shimano cassette hub, and replacing it with a threaded jawn for track cogs: https://surlybikes.com/parts/fixxer (Folks always complain that these get loose-ish)
3- Front disc hub conversion: The front hubs can be spaced out to 120 or i guess up to 130. I'm doing this on an old XT hub so I can run an old-timey American-made cruiser fixed without spreading the ends. I got the hub, axle, and nuts; just need to order up a 6-bolt cog and some spacers.

But, even with all of this hocus-pocus, a traditional track cog is tough to beat. (Altho, TBH, 6-bolt cogs get more popular all the time...)

Wish I could offer more insight; of course I've thought about finding a way to mod a freehub as you've described, but my inner coward (or reasonable person?) has always stopped me from trying.

FBinNY 

I haven't looked at that hub but be aware that the ratchet ring on many freehubs is threaded to the shell. Enough reverse torque could walk one out. This design is generally limited those designs like Campagnolo where the freehub body rides on it's own bearings and connected to the shell via the ratchet mechanism.

OTOH those with self-contained freehub bodies with the ratchet within and connected via a spline and nut don't have that problem. Yet consider that the spline may not be up to the very high torque loads involved in reverse pedal braking.

So, you might be able to go this route, and it may work out OK, but I'd make sure I had at least one brake just in case.

deuce808

the sram torpedp would require a hub swap so in that case i would wait for the philwood

the surly fixxer requires a splined (star shaped) shimano hub that the fixxer bolts onto. i hav one ona hed3 and if it coupld work on the sram i would me all for it.

never thought about the front hub conversion. i heard about it earlier but again that would be a hub swap

my primary goal would be to make the sram hub work while making all mods reversible so i can swap or sell it later as a road wheel. do you think metal shims would break? think keyways found on motor cranks (that allow for a pulley to meounted for example) i have a few of those lying around. or do you think that the pawl/splines on the freehub body would break or shear? i dont skid and i use a brake.

deuce808

i didnt realize that the part that the pawls were in was threaded on. looks like apart of the hub at first glance. i dont skid (ever) and i use a front brake. so locking into a fixed/forward rotation should be less stress on it? i have a surly fixxer on a hed3 and its held up for about a year now, the bearing sucks but thats another story.

David Broon 

Jeez, why are you so sane over here?

For the rest of you, look here:
https://www.bikeforums.net/showthread...n-a-fixed-gear

deuce808

because these guys offered advice n theory instead of insults and redicule. respect deems respect

zukahn1 

Let me make it simple if you want to run FG/SS great. I will tell you the same thing nearly any better shop mechanic will you need to buy a proper FG/SS wheel or your build will likely suck and fail if you ride it heavy.

deuce808

in your opinion the s80 is not a proper wheel? low spoke count/carbon fiber. or do you mean that if i run a proper hub then that constitutes a proper wheel? just clariying.

fietsbob

a couple tack welds Fusing the 2 parts ofthe freewheel driver on the freehub is direct.

you can probably clean it up, taken off the hub, Submeged in a tin can , with solvent in it
remove all grease and melt acid core solder poured in around the bearings ..

But, You still have a weak wheel with a narrow flange spacing and a Imbalanced dish asymetric braced wheel ..

Better Plan : Buy /Build a Proper Fixie wheel for the 135 wide frame spacing , if that is what You desire..

Freewheel/flip-flop or double Fixed. whatever...

deuce808

i do not want to run it at 135mm wheel spacing. i want to run it at 120mm for a track frame. im not sure you can weld the internals of the sram hub because aside from the actual pawls/leaf spring system everything else in there is aluminum and very thin gauge. the leaf springs behind the pawls flex when forward pedaling is stopped allowing freewheel action.

may be i will just wait for the philwood. although i would still like to try this on another wheel to see if its doable.

FMB42

Have you considered the possibility of your "modified" sram freehub being permanently damaged if your "fixed gear creation" fails?

shelbyfv

The linked thread is amusing and apparently not the first concerning this "plan." Like a dog that takes dumps until the yard is full and then moves to the next one....

surreal

Deuce,

I wasn't suggesting that you use any of the products I'd listed; I just figured you might find them to be entertaining "food for thought" about backdoor FG missions while you wait for your Phil hub...

...because, overall, I think your best bet is to wait for the Phil. Your plan is interesting to think about, but I think it may be dangerous in practice, plus risky in terms of possibly losing a perfectly good road hub. (BTW, I agree with you re: the prospect of tack-welding it effectively.)

-Rob

Grand Bois

And they can't spell.

Kimmo 

Could you disassemble and take pics of the hub for us?

Or link to an exploded diagram maybe?

Some of us aren't familiar with SRAM hubs.

wle

i would not trust the shims
i have broken a wheel drive before, those big teeth where the freehub meshe with the wheel to drive it
if that broke on a fixie, and you didn;t have brakes, you would die

wle

Booger1

Tack weld or JB weld the pawls to the spur gear......It's like making a Lincoln Locker for a bicycle.

There's no stress when peddling....the pawls will be engaged when your ready to stop.

As long as the pawls stay on the spur gear,no problem.

Whether the pawl pivots can take that stress or not,that's another story.....

wle

==what about when backpedaling to slow down!!
--wle

Booger1

I just figured the guy has brakes on his bike......or is this a track bike?

If you need to lock the wheel to brake.....Degrease,mix up a couple tubes of JB/epoxy/casting resin and fill the freehub with it,bearings and all......you won't compress that.

If your good with your hands or have some machinery,make an aluminum slug to replace the ratchet.

If the parts are made of the same material,you can tig weld them together if you can get to them.

fietsbob

Take it apart and you got all those tiny BBs to replace..

since it's "theory", [OP's term] and not practice. (aint got to say where to, get things or if they really work)

a steel ring of the right diameter, and the size of the bearing ball can replace the ring of bearing balls.
since the freewheel function is being killed.

Oh another Fixie without much thought to the how or probably why.
just a follower of fashion.. get the right parts dude..

can there be a group buy of "dead peasants insurance", so we can profit off others foolishness?

The_Joe

Could this work in theory? Yeah. Should you do it? Sure. But theory and practice are two different things. Why sacrifice a good road hub to make a half assed track hub? There are numerous options for track wheels that aren't $200 Phil Woods. In fact, I find a hole in your thought process where it makes a jump from a cheap conversion idea to a high end hub with no middle ground.
I understand where you're coming from as a guy who thinks outside of the box. I've done it for a long time. Long enough to know that in the centuries of bike manufacturing things have become the way they are because those are the things that work best. What you're doing may very well work and may very well for a while. But the proper thought of a mechanic, engineer, or anyone considering safety should never be what works now for cheap but what works properly.

This was me being as supportive as I can be. You've spent all of this effort making a point and seemingly none of it actually doing what you set out to do. Go tinker.

Dannihilator

I would highly advise not doing this, it's not feasible or safe.

linus

Just rebuild the wheel with a cheap track hub. Too much work without much gain. Not to mention dangerous.

Dannihilator

^This