So I'm trying to install a 1/8 17t EAI cog on a Weinmann DP18, which I believe comes with a formula hub but the damn cog would only go halfway. I know about the different sizing for phil and campy hubs but the thing just won't go in smoothly. I installed a cog from my kilo and it fits perfectly, so I compared both threads on the cogs and it seems the EAI has smaller threads. Do EAI made BSC and ISO cogs? Anybody had the same issue? Should I just force the damn thing? Also all parts are new and threads looks good. I probably need to email Ben's.

ISO, says it right on the cog... never had any issues myself, just use globs of grease while installing.

...works fine on my formula hub.

Grease it up, and tighten down with a chainwhip, or use a vise, by wrapping the chain around the cog, and tightening the vise, then turning the wheel like all busdriver style.

Great advice, the only thing missing is a big hammer.

That would be my first step. Do you have access to another hub?

I have the same exact setup, no problems.
Post a closeup picture.

I have the same exact setup, no problems.
Post a closeup picture.

Did that with lots of grease and still the same.

Too scared to strip the thread.

I tried to put it on my stock kilo hubs and same thing, would only go halfway and then stuck.

I just got to work so picture maybe later tonight after watching My Bloody Valentine

Have you checked the threads on the hub as well as the cog to make sure none of them are damaged? I have that exact setup, no problems.

It is a very precise fit, so make sure that the cog and hub threads are very clean. Use a tooth brush and some chain cleaner to clean both threads. Carefully inspect all around the threads to see if you have damaged them. Hopefully you haven't cross threaded your hub already. Probably not the cog, as it is steel and harder than the threads on the hub, but check anyway. If all is well, apply a thin coating of grease and carefully thread the cog on. You should be able to seat it all the way with just your hands.

Ahh, I just saw that you tried it on another hub and the same thing happened. Sounds, like you have some debris in the cog threads. I would carefully inspect them, may be a milling remnant, or maybe the thread was damaged somehow. But I certainly wouldn't be cranking it down on any soft hub threads until you know for sure.

I just got an EAI from Bens this week and having the same exact problem with my hub threading. It starts off fine but is very hard to get on without using the chain whip. Bad batch? mine is a 1/8 17t. let me know what you find out. Feels like it is x threading. Mine are on Bontragger x lite hubs. posted last night about the problem https://www.bikeforums.net/singlespeed-fixed-gear/468794-help-having-hard-time-get-cog-onto-hub.html

Also how important is it to have a thin washer between the cog and lock ring? what do i get one from?

ah dang I just bought an EAI 17t 1/8 but have not yet installed it. I will update when I do.

Thread on the hubs have no damage.

I have yet to brush the thread on the cog but I was cleaning it with a cloth a and the thread on the cog seems good.

Hey thanks for letting me know. I will probably bringing the cog to my LBS tomorrow and see whats up.
I also saw this from another forum. Don't know if i can cross post but see below.
https://www.orangecountyfixed.com/200...e1/#post935765

Yes, please let us know.

Plot thickens: 3 Euro-Asia Import 1/8" x 17T steel cogs all thread on half way then stop. Sounds like a bad batch. Or someone forgot to change the tap.

I would return it. DO NOT FORCE it, you may end up damaging your hub threads.

zac

i have a 3/32 EAI 17t cog on my formula hub, and it went on fine.

this is why i will be going to the LBS to buy a new 1/8 17t cog and have them install it. skip all of these problems from the get go

^^^ the bike shop will also force it on too!

precisely

boo

well, did everyone order theirs from Ben's who are having problems? Seems like 2 of the problems were from there, maybe 3. Must be their batch, if thats possible

I remember initially having to force my EAI cog onto my Formula hub. After that, all my other EAI cogs spin on and off this hub smoothly.

Didn't have to force mine, screwed on smooth. 17 tooth, 1/8" EAI cog on a Formula hub. Got mine a couple months back though, right after Ben's re-stocked from everyone making a run on 17 tooth model.

dumb question, but I have to ask: Will a fixed cog screw in on the freewheel side of a flip/flop hub? If so, my brand new 17t 1/8th EAI cog from Benscycle is having the same problem as people above. Formula hub.

edit: i'm not trying to run a fixed cog on the freewheel side, i just wanted to test if my cog would screw in smoothly.

It should screw in smoothly as same as the fixed side.

the freewheel threads are the same as the fixed side besides the smaller diameter for the lock ring. So wow that makes 4 with the same problem.