Rohloff Advice

[crossy]

I've just bought a bike with Rohloff gears a German make Schauff. It has a chain tensioner on it at the moment is there a way to lose the chain tensioner. I think it has to do with the bottom bracket. Any advice welcome.

 

[02GF74]

attach a string to it so you don't lose it.





no idea what you are asking here, a photo would help.

 

[MacB]

I'm guessing you mean that the existing bike has a normal BB and vertical dropouts. Thus the only way to provide tension is via a chain tensioner similar to a rear derailler. I'm further guessing that you'd like to be able to just run the chain straight from cog to chainwheel with no tensioning device interfering. If so then options are:-

having different dropouts put on the bike, either horizontal or track end(still horizontal but rear facing) - this allows chain tension by positioning of rear wheel - an expensive option and I'm not sure how feasible if your frame is aluminium.

Using an eccentric bottom bracket - if your existing BB shell is standard(which it probably is) then you either need a new BB shell(a new frame might be cheaper!!!) or to invest in a Trikstuff Excentriker gadget which converts a standard BB to eccentric. - last I looked the Excentriker was about £120 and I have read complaints that it doesn't allow enough adjustment.

File away part of the existing vertical dropouts to provide enough movement to tension the chain. Obviously a fair element of risk here but have seen a few claim it works fine and not seen anyone actually admit to borking a frame in this manner. This would generally be done in conjunction with calculating a magic chain length, ie the exact chain you need for your BB to dropouts distance plus chainwheel and cog. I think it can also involve the use of a half link in the chain, depending on length requirements.

Go for a magic chain length on its own, it seems to work for people doing SS or fixed(not 100% on the fixed) conversions. A hub gear is basically the same concept and is much less susceptible to a slack chain.

If that wasn't what you were asking then apologies, I was guessing

 

[ufkacbln]

My Thorn has an eccentric bottom bracket which allows adjustment and tensioning.

On the Catrike, the chain is not tensionable, so the tensioner fulfils this task.

Both work.

 

[bike_the_planet]

I've just bought a bike with Rohloff gears a German make Schauff. It has a chain tensioner on it at the moment is there a way to lose the chain tensioner. I think it has to do with the bottom bracket. Any advice welcome.

MacB's reply is essentially correct.

However, it's a bit of a long shot but you could try a half-link chain.

As MacB stated, bike frames intended for derailleur gears have vertical rear dropouts. Because of this there is no provision for moving the rear wheel slightly further aft to compensate for the chain stretch that occurs as chains wear.

On a bike with derailleur gears, the derailleur swing arm constantly compensates for this slight change in chain length, but when you have hub gears, without a chain tensioner, then the chain will stretch and sag.

One way around this is to wait until the chain stretches enough and then remove links to shorten it.

The problem with this is that a standard cycle chain has alternating 'outer' and 'inner' links (look vertically down at each link on your chain and you will see that each link is is either narrower or wider than each adjacent link).

Because of this you would need to remove two links (each one half-inch pitch) to shorten the chain, bacause you cannot join either two inners or two outers together. You can only join one inner to one outer.

That's a total of one inch and means you'll have to wait until the chain is really sagging before you can remove two links. By the time that it's sagging enough to be able to do this, the chain will keep slipping off the sprocket making it virtually unridable.

Half-link chains are used on BMX bikes (see here). One end of the link is an inner, the other an outer. This means that you only need to remove one link (half an inch) and you can still join two ends of the chain together.

I haven't tried it myself, but I suspect that, if you play around with your rear sprocket size, chainring size and chain length using one of these chains, you might just be able to dispense with the tensioner on a bike with vertical dropouts and no eccentric bottom bracket.

No guarantees but it might just work.

Cheers

 

[bike_the_planet]

I've just bought a bike with Rohloff gears a German make Schauff. It has a chain tensioner on it at the moment is there a way to lose the chain tensioner. I think it has to do with the bottom bracket. Any advice welcome.

MacB's reply is essentially correct.

However, it's a bit of a long shot but you could try a half-link chain.

As MacB stated, bike frames intended for derailleur gears have vertical rear dropouts. Because of this there is no provision for moving the rear wheel slightly further aft to compensate for the chain stretch that occurs as chains wear.

On a bike with derailleur gears, the derailleur swing arm constantly compensates for this slight change in chain length, but when you have hub gears, without a chain tensioner, then the chain will stretch and sag.

One way around this is to wait until the chain stretches enough and then remove links to shorten it.

The problem with this is that a standard cycle chain has alternating 'outer' and 'inner' links (look vertically down at each link on your chain and you will see that each link is is either narrower or wider than each adjacent link).

Because of this you would need to remove two links (each one half-inch pitch) to shorten the chain, bacause you cannot join either two inners or two outers together. You can only join one inner to one outer.

That's a total of one inch and means you'll have to wait until the chain is really sagging before you can remove two links. By the time that it's sagging enough to be able to do this, the chain will keep slipping off the sprocket making it virtually unridable.

Half-link chains are used on BMX bikes (see here). One end of the link is an inner, the other an outer. This means that you only need to remove one link (half an inch) and you can still join two ends of the chain together.

I haven't tried it myself, but I suspect that, if you play around with your rear sprocket size, chainring size and chain length using one of these chains, you might just be able to dispense with the tensioner on a bike with vertical dropouts and no eccentric bottom bracket.

No guarantees but it might just work.

Cheers