wolfchild

I have a fixed gear bike with a flip/flop hub, it's my commuter/tourer bike. I have always used the fixed side of the hub with a lockring ever since I got the bike new. The freewheel side was just sitting there unused all this time , I never run it as a freewheel . So I decided to instal a track cog on the freewheel side, that way I can have two gear ratios (44/16-18). I've used the rotofix method to tighten the cog with lots of red locktite permanent , as there is no provision for a reverse threaded lockring, hence the locktite. Well I didn't know what to except, so I went for a 112 km ride today, with some uphills and downhills along the route, but mostly flat. The cog never came loose, it's on there tight. I do have front and rear brakes but I never even had to use them at all , I just slow down and stop using my legs and backpressure on the cranks ( no skidding), and the cog just stayed on there tight. I plan on riding like that for the next while just to see how realible this method is.

schmere

Cool story bro.

acoustophile

I don't think it really matters that you rotofixed that cog on if there's no lockring. With enough locktite the method you used to the cog on is redundant.

Moximitre

Rotafix is A-OK. Don't even need the loctite. Just don't go so hard you strip your threads.

elTwitcho

I rotafix to take my cogs on or off. I find a chainwhip tool doesn't get everything tight enough IME

filtersweep

Red loctite is all fun and games until you need to remove something (need a lot of heat).

I survived riding on a suicide hub for thousands of miles several years ago. It is fine if you have at least one brake-- (never had a problem).

But rotofixing alone won't keep a cog in place.

operator

+1

Moximitre

This is incorrect.

elTwitcho

For skip stops and skids I would tend to agree. The Rotafixa was originally done on the track where people don't do the same kind of silly **** we do on our bikes. It's probably fine for the track, not at all for the street.

stryper

can't you use a bottom bracket lockring in the single speed side of a hub? I know it isn't reverse threaded, but it's the same principle as using two nuts on a bolt. It will help keep it in place

wolfchild

If I ever have a problem with my Rotofixa/ red locktite and no lock ring method, I will post it and let everybody know. I've only been running it for a day so it's too early to tell how realible it is. The threads on me hub were perfect when I did it. 66 gear inches is an easy gear so I hope it will hold up. On my fixed side it's 74 gear inches so I definetly want to have a reverse threaded lockring.

not required

+1 on the bottom bracket lock ring, i rode mine with no loctite and a bb lock ring held with skids and everything, never slipped once.

what is the Rotofixa thing everyone is talking about?

Yo!

BB lockring plus freewheel side plus loctite is your generic suicide hub.

Rotafix is your quick and effective way to remove or install a fixed cog:

https://204.73.203.34/fisso/eng/schpignone.htm

ianjk

Actually, you put more torque on the drivetrain with the lower gear.

PedallingATX

should be fine. Rotafix works pretty well, loctite is an extra measure. And if you put a BB lockring on there, then you really shouldn't have to worry.

The fact that you have 2 brakes takes away the safety concern b/c even if it unthreads, you will be okay.

loi

Doing it correctly won't strip your hub. loctite red + BB lockring will last you. my friend does skip stops and skids and it still rides perfect after half a thousand miles, and its still strong, just keep retightening it to make sure it stays put

filtersweep

You are kidding yourself if you think the BB lockring helps at all. OK, in all fairness, maybe it contributes by 2% or something--- but it isn't making a significant contribution.

ottothecow

I'm sure someone could do math and prove how much it helps (particularily when held on with permanent loctite).

I can't do the real math since I know nothing about the binding strength of loctite but I can do this rough estimate based on things currently sitting on my desk:

Cheap stamped cog: 5 thread valleys,6 threads
BB Lock ring (mid 70's): 2 thread valleys, 3 threads

Thus we can estimate that force required to unwind a cog and lockring is 40-50% greater than the force required to break the bond on a lone cog.

Of course this requires that both are tight initially as if the cog has room to unwind a little bit and break its bond independent of the bonds on the lockring, the lockring will do nothing (similar to how trains function by having the cars not connected rigidly)

jlin

fyi, OP, this is definitely not safe. without a lockring, you must must must at the very least use loctite. though rotafixing is a great way to tighten your cog, without a locking mechanism for the cog to remain in place, your cog will inevitably come loose again.

mihlbach

The red loctite was unnecessary...you'll have a ***** of a time getting it off..good luck with that.

When you rotafix the cog, you are able to apply more torque than you would ever be able to with a chainwhip or with your legs through the drive train using a normal gear ratio, so there is no way you are going to unscrew it during normal riding especially if you are careful about it. Nuts-to-stem skidding is fine. Ass-on-seat skidding and skip stopping (the kind where you lift the wheel off the ground and lock your knees) are not advisable, although I was able to do this for years with a rotafixed cog with no loctite and no lockring and never had an issue. At the time I weighed 225. Just don't rely on your DT as you main source for stopping and you'll be fine.

Edit: Your reasoning about gear ratios is backwards. The lower the gear ratio, the more power (and torque) you can generate. You generate less torque with higher gear ratios..thats why its harder to pedal high gears...because you are generating less power. It not clear to me which of your cogs is on the rotafix side, but I would seriously put the smaller (16t) cog on the rotafix side..its much less likely to spin off.

jlin

again, i can't stress this enough, this is not safe!

although rotafixing is a very strong way to tighten your cog, it does not preclude the need for some sort of locking mechanism! without one, your cog will come loose gradually while riding!

ideally, this locking mechanism would be a lockring. but, since your hub doesn't have threading for one, you'd at least need to use something like loctite.

mihlbach

LOL...https://dictionary.reference.com/browse/alarmist

jlin

lol...https://dictionary.reference.com/browse/idiot

jpdesjar

Internet fisticuffs!

mihlbach

Obviously. Wasting my time on BF should be the biggest clue.