Fatn40

Won't a BMX cog fit on the wheel?

jaypee

Yes, however, most mountain bikes have vertical dropouts which do not allow you to slide the wheel forwards or backwards to adjust chain tension.

RedDeMartini

Well that thread is nicely sewn up...

mattface 

They are not required, they are just one way of getting proper chain tension with vertical dropouts. Another more elegant way is to use a White Industries Eno hub, but they are pricey. The best way is probably to get a frame with horizontal dropouts, or track forks so you can slide the axle to adjust chain tension. All SS specific frames have some way to adjust the chain. most of them use Track forks in place of horizontal dropouts, but a few have eccentric bottom brackets which is a very slick solution. Pricey, but slick.

jaypee

Goddamnit, you just HAD to go and one-up me.

Aeroplane

New to the club are sliding dropouts:



These are nice because they can come with derailleur hangers too, incase you want to revert to gears.

isotopesope

the sliding dropouts or ebb's are nice too if you run disc brakes on a ss.

i have the iro highlander, which has trackends... thus, no tensioner required. however, i just put a chain tug on because i kept pulling the wheel forward and dumping my chain on fast steep ascents. not that i don't love being sprawled out like a turtle in the middle of the trail...

abeyance

Paragon Marchine Works makes the greatest stuff. They are Phil v.2

jim-bob

No chain tensioners on my SS mountain bikes.

Aeroplane

Good lord... Last week, I was riding and my wheel wasn't in the rear dropout securely, so I dropped the chain on a stand-on-pedals climb. HUUURRRRRRR, stem to stomach in no time flat. Thankfully, I did not turtle out.

Fatn40

Thanks....I read about horizontal dropouts on SS roadies but didn't put 2 and 2 together. And while I looked at 200+ pages of fixie photo's I noticed some MB's had tensioners and others didn't.

Sucks that roadies and MB's are lumped together in the fixie photo thread.

slopvehicle

I own both types of bike, and I disagree.

Johnny Vagabond

They also help to keep your rear wheel from sliding forward in the dropouts and throwing your chain when you mash down really hard on an ascent. If you're a heavier rider, this is a frequent problem.

EDIT: Also, if you use a smaller cog (i.e. 16 tooth to a 32t chainring), that torque can screw with the rear wheel, too.

Aeroplane

Those are a different thing altogether, but I've marvelled at the confusion of calling both chain tensioners.

I think what you're talking about should be called "chain tugs", at least in the realm of SS bikes. Just an opinion.

Cynikal 

Who makes these? I planning to build a CX frame and these would give me the opton to go SS/fix or geared.

Fatn40

I'm not sure why you disagree...I have not found any way to search for just the MB SS photo's in that thread. What's the trick?

Aeroplane

https://www.paragonmachineworks.com/
These are the same thing that is on the Kona Unit, Explosif, and Sutra.

somnambulant

On-one also uses sliding drop-outs on the Inbred.

jaypee

I actually own one. While not as pretty as the Paragon ones, they work quite well. I'm currently running it as a 1x9 at the moment, will go SS once my new hubs arrive.

(btw, I love the Inbred. Long top tube, short stem, feels like a BMX bike...)

(edit)

Aeroplane

Yeah, the reason I didn't mention them is because the on-one dropouts don't have the disc brake tabs attached to the sliding part, it's attached to the frame. So you have to deal with all that malarkey.

jim-bob

Paragon does beautiful work.