Chain Tensioning

[Thomas777]

My wife's bike,not a Thorn, is a Dutch step through touring bike that we bought a few years ago while in Europe at the end of our tour. I built it up ,after painting as it came in raw steel, with a derailleur set up. But soon changed it over to a Rohloff which she really likes!
We just returned from a 2 month tour in Europe and a few times during the trip I had to re-tension the chain. It is a simple matter, just loosen the sliding dropouts and pull the wheel back. But as much as I have worked on her bike I never noticed the 2 small threaded units that would accommodate screws to " push" the dropouts back. After contacting the shop in Rotterdam,Bikes4 Travel, they said that was used for tensioning belt drives and it is not necessary for chain drive.
Well back home after the trip I was cleaning up the bike fitting a new chain I installed the 2 adjuster screws.
I like 'em!!!

Would like to hear more from others.
Thanks!!

[martinf]

But as much as I have worked on her bike I never noticed the 2 small threaded units that would accommodate screws to " push" the dropouts back. After contacting the shop in Rotterdam,Bikes4 Travel, they said that was used for tensioning belt drives and it is not necessary for chain drive.
Well back home after the trip I was cleaning up the bike fitting a new chain I installed the 2 adjuster screws.

I've had similar types of adjuster screw, but not recently. Very useful for fine tuning chain tension on single-speed, hub-geared and fixed wheel bikes.

My old lightweight derailleur bike from 1977 has something a bit similar - Campagnolo Road long rear drop-outs with adjusting screws. AFAIK the function of these screws is to position the rear wheel precisely in the rear triangle, and nothing to do with chain tension. 

[Andre Jute]

They're standard fitment on horizontal long-slot rear-ends for hub gears, and my memory is that they were used for chain tensioning by moving the axle back in the slot -- the axle fit directly in the slot, not in a sliding hanger a la Rohloff. Gazelle had an extra component to each side, so that the tensioning could be done from behind the axle with a socket spanner over a small domed nut. If you look up the instructions for Gazelle with Nexus hub gearboxes around the turn of the century, you'll find these adjusters; my bike was a Gazelle Toulouse from about 2002.

[mickeg]

I think were talking about two concepts here. 

The sliding dropouts could be adjusted with those screws in the original post.  And it sounds like a great idea, you could turn each screw the same number of turns each time you adjust it to make sure your wheel alignment stays the same.

Or, the position of the axle in a non-moveable dropout could be adjusted with some threaded fittings.  The Raleigh DL-1 had some adjusting fittings for that purpose a century ago that would hold the axle back away from the bottom bracket.  I think that Surly makes some of those now for some of the people that want to use an IGH on a bike with horizontal dropouts.