Bolt on cogs

so whats the opinion on the bolt on cogs londonfixiebike are selling -
the ones which bolt onto a front disc brake hub.

Are they a good idea?
or is this just another fiendish way to steal my money...

I have one on a bike. It seems good yo me.

good value or is it cheaper to get the parts?
I ride single-speed and haven never converted to fixed before.

It's easier to change cogs clearly so that's an advantage. Price wise it depends on the hub. I wanted a 135 spaced hub so it was that or a surly hub, I thought I would try the bolt on. Similar price for me.

i hadn't thought of the advantages of being able to change cogs quickly.. thats a good point

thanks very much for the advice by the way, its nice to get a prompt reply!

Any shops carry these? Just picked up a 26" rear wheel (thanks Rocksteady!) for a polo bike. Thought I was going to have to swap the hub, but seeing as the hub has a disc brake mount, may as well try this out.

Whats the spacing on MTB front hub? Could this be used as a cheap fixed hub with the bolt on cog?

That's the idea, I guess.

Although it would be interesting to know if there is any other advantage to one or the other.

Sheldon Brown has front hubs at 110mm so you'd need 10mm of spacers too. not sure about chainline.

Think you may need to change the bolt every 5 months or less, but then it is for a polo bike after all.

I'm using a 135 rear hub. I haven't put thought into the chain line yet. Just assuming I'll get it to work. I'm also assuming there is no different in bolt patterns for front and rear discs?

I guess a ready bought front disc wheel would be dished in the wrong direction, if any dishing is needed at all.....

Are front wheels with disc brakes dished to compensate with the forces? Didn't know that. Interesting.

Think you may need to change the bolt every 5 months or less, but then it is for a polo bike after all.

Not if you use good bolts.

Tommy, did you order yours over the interwebs?

Are front wheels with disc brakes dished to compensate with the forces? Didn't know that. Interesting.

I have a disc hub on my mtb and its dished so that even though the side with the disc carrier is longer the rim still sits in the middle of the hub rather than the middle of the flanges.
Does that sound a bit spacky?

I guess a ready bought front disc wheel would be dished in the wrong direction, if any dishing is needed at all.....

I've built one of these up before. You just dish it the same as if you were dishing any nrmal front disc hub. Its exactly the same.

Think you may need to change the bolt every 5 months or less, but then it is for a polo bike after all.

No you don't. Think how much force goes through those bolts on a DH bike with 8 inch rotors. Lots

Tommy, did you order yours over the interwebs?

Yep http://www.velosolo.co.uk/intro.html

Personally 6 m6 bolts holding a sprocket on seem like a bad idea. A shimano splined disc mount with a lockring, wouldn't sound so scary. I just can't see disc brakes exerting the same forces as riding fixed wheel.

Not to mention rounded off-bolts, with threadlock on, when it comes to removal.

disc brakes exert more force that a sprocket, just look at the diameter difference and work out the forces with leverage.

Seems to be fair amount of assumptions going on here. Why would 6 bolts spreading the load not be up to it, why would you need to change bolts every 5 months (where does a specific number such as 5 months come from?)

I used one on an XT hub on a off road fixed bike for about 6 months and it was great. No problems at all and nice and weatherproof being based on an XT hub.

You do need to make sure that the disc hub you choose has the right spindle size otherwise you may find it hard to get a bolt on spindle to replace the QR. That is why Londonfixie use XT I believe as you can use a standard M10 and use the existing XT cones, ball bearings etc,.

4/5 chainring bolts are always up to the task, why wouldn't those holding a sprocket on not be!?

personally, i think it will be fine, no probs, just what the doctor ordered etc.

disc brakes exert more force that a sprocket, just look at the diameter difference and work out the forces with leverage.

Yes appreciated, but you never drive your wheel with your disc brakes... only stop.

I know bolts are extremely strong etc esp. 8.8 or 10.9 tensile. Just seems a bit backward and more effort than buying a 120/130/135mm fixed hub.

Compatability becomes an issue with having to use a 3/8, 9.5mm or 10mm rear axle in a front hub, sounds a bit heath robinson.