DQRider 

I have an old Gitane Gypsy Sport that I have converted to a Nexus-8 IGH. This one has the forward-facing diagonal dropouts, so I do have enough fore-and-aft space for chain tension adjustment. However, it seems that the chain isn't holding tension, and loosens up after only a short distance. I don't want to overtorque the axle nuts, but I need to find a chain tensioner that will work, without conflicting with the anti-rotation washer.

I found these:

... but I'm not sure they will work.

Here's the bike in question (sorry, I don't have a closeup of the drivetrain yet):



It doesn't look like these tensioners will work in this application, unless I use the tensioner to replace the anti-rotation washer. Is that going to work? Is there another solution?

Thanks,
DQR

Mr IGH

I've run the MKS tensioners in the past, the anti-rotation washers on the outside and the tensioner on the inside:


The MKS tensioner is made of steel and it's thin at the axle:


In the end I learned to really crank down on the axle nuts and let the non-slip surfaces on the axle locknuts and anti-rotate washer do their job. Some folks scrape the dropout paint off but I didn't need to.

fietsbob

Your mechanical logic is backwards .. Your gadgets are for rear opening dropouts , anyhow.

Leave the Anti rotation washer * and just lean on the wrench harder , you are not getting the axle nuts tight enough.

find the torque specs and buy a torque wrench if you want to be Professional about it.

* the anti rotation washer pair is important in the functioning of the Internal gears ..

A toothy washer to hold the axle firmly in the dropout, will bite into the paint accept that.

DQRider 

Thank you, gentlemen, for your advice. I will answer you each in turn.

Mr. IGH: For whatever reason, I wasn't thinking about using the tensioner on the inside of the dropouts - that makes perfect sense. The MKS tensioner looks like it will work when installed that way. I'm not worried about the paint on the dropouts - that was toast after I cold-set the rear triangle to accept the Nexus hub and then realigned the dropouts. I just sprayed it with Boeshield T9 and then installed the hub.

fietsbob: You must be a "Professional" - I've run into that sort of attitude in bike shops before. Those are the places I only visit once. What you don't know is that I worked on Marine Corps jets for 10 years, have built motorcycles from a box of parts, and have all the aptitude I need. Bicycles are a new hobby for me. What I lack is specific knowledge, and that is why I go to experts like you for help.

Now, my mechanical logic is actually spot-on. As long as there is horizontal travel in the dropouts, an IGH can be used without the need for a sprocket-style tensioner. It doesn't matter if it's rear-opening or front-loading, although I'll grant you that rear opening is easier to live with in this application. I do have a torque wrench, and I will take your advice and use it. I'm pretty sure I saw the torque spec in the manual. FWIW, these particular AR washers have a key to fit into the axle slot, so once it is torqued-to-spec, it ain't goin' anywhere.

So, I'll give this a try, and let you know how it goes.

Thanks again,
DQR

Dan Burkhart 

You missed the point of Bob's post. The tensioners you referenced are for rear facing dropouts. They are of no use with yours.

DQRider 

Ah, I see what you mean. My apologies, Bob.

Mr IGH

I'm pretty sure you can get those tensioners to work front or rear facing dropouts. But it's moot, OP needs to crank down on the axlenuts, I've never been able to strip a Shimano IGH axlenut, no slipping even with 26x23 primary ratio on my Moonlander.

DQRider 

Well, I tried two different designs: one similar to that pictured in my first post, and another little cheap thing that I bought for a 3-speed last year. The first one was too thick, wouldn't work inside or outside. The A-R nut is quite thick on these hubs, and I really don't think anything would work on the outside. The cheap version works when installed on the inside, but it's a tight fit. Still, it's better than nothing. And yes, I torqued the hubnuts to 34 ft/lbs (45 Nm) as called out in the manual.

And I want to apologize again for assuming "technician's arrogance" from fietsbob's answer. Different people communicate in different ways, and I shouldn't have been offended.

Thanks everybody for helping me out.

DQR

P.S. While I was struggling with this, it occurred to me that "Problem Solvers" might want to look at making a combination A-R nut / chain tensioner for these IGH conversions. I'll be sending them a message as soon as I'm done typing this.

alcjphil

One thing to keep in mind is that your chain has to have a small amount of slack, it should not be under any tension. It should be possible to move the middle of the chain up and down 1/4" to 1/2" . If you can't it is too tight

DQRider 

Yeah, I got that. With moderate finger pressure, I get an average of 1/2 inch of play both top and bottom. It's the same principal with motorcycle chains.

alcjphil

Good, sounds about right. Just wanted to make sure you were aware.

DQRider 

Thanks! This forum is a great resource, as long as I approach it as a student. I'm always in such a hurry to master these things... gotta learn to slow down.