Discos

DISCOS
So on my Single speed MTB (vertical dropouts so I have an old rear DR as a chain tensioner) I've been getting a few problems with the chain coming off when going off kerbs and stuff. I've fixed some of the problem with straightening out my chain line a bit but I'd like to do more. I've seen this product before but I figure I could just put the two largest chainrings from my destructed cassettes either side of the one I'm using (with a couple of spacers of course) and get the same effect. What do you reckon?

Also what is the ideal chain tension for a single speed bike where you use a rear DR as a chain tensioner. I seem to remember some images showing that you should pretty much have the chain as short as possible whilst the chain touches both jockey wheels (I could probably lose a couple of links from my chain at the mo).

Cheers all.

btw DR = dérailleur.

also would I find a huge difference chainging my rear dr for a proper chain tensioner?

Bearing in mind I'm trying not to spend money on this bike if at all possible.

That looks crazy, just get a singleator.

Yeah I'd like one but the Surly Singelator sells for $129 here in Australia. Yeah right!

As I said the less money I spend on this bike the better.

and thats the reduced price

ooooo here is a copy for $39!!!

scott not scot wooh man...it'd be cheaper to get someone over here to buy a singulator and post it to ya!

scott not scot they're less than 30 notes over here...and postage won't be much....:)

AUD is 3 to 1 on GBP.

£30 here = $90 there.

Add postage, and you're not far off the price he's seeing.

The benefit is simply the avoidance of tax if it's marked as a gift. That's all.

I found a RD hacked up to be fine, with constant tweaking! The chain should be as short as possible.
I removed the top jockey wheel and one side of the cage (replaced with a random bolt) so that I could use a 1/8 chain. Also I twisted the cage round to deform the spring and give me more tension.
Apparently it's better to use a short-cage rear DR, some trials riders use roadie ones. If you are running 3/32 then this should stop all your hassles.
Have you cut the cable short so that the end that's supposed to go into the lever actually goes into the barrel adjuster. Passed the cable through the barrel adjuster and into the derailleur pinch bolt as normal, then crimp the free end of the cable as normal? This lets you sort out chainline on-the fly.
Peace.

It's actually about 2.3:1 so £30 here is about $70AUD. $150AUD is a bullshit price, even with postage.

"disco" was the name given to quasi-palsied children at my school. that and 'hutties' on account of them having their lessons in the temporary huts. good, innocent, carefree times.

They were called shoulder-biters at the school I went to. A far more visual term I feel.

Window lickers (visual too)

so I'm probably best off just getting the copy and forgetting about the discos?

I used a derailler on the GT and it worked great for ages. I now have a singleator and something is making noise.. needs to be sorted... not sure what it is..

Nah, that's the odd thing.. can't see anything causing the noise. Chainline looks fine. Everything looks fine. Odd.

Mine has got noisy once I worked out that could get it much tighter with a cone wrench after removing the nut on my QR hub and shifting the axle out the way than with a pair of pliers. Does it sound like a really metallic vibration? I'm thinking I need to just loosen it off a little.

flip the bike upside down and loosen the bolt that the jockey wheel slides back and forth in.....pedal the bike and push the jockey wheel in or out till it doesnt catch anywhere.....

got a mental picture of hippy lying on the floor clipped in to his bike and pedalling like mad

stop hijacking my thread! I need my answers!!!

:p

You have your answers - don't use discos, derailler as a tensioner is fine and given the price of a proper tensioner I'd definately keep the DR.
Tension should allow you to spin the pedals around by hand so it doesn't bind but not so loose that you throw the chain

The tension on this was possibly too high but I'd rather wear shit out than have a loose chain slip.