Singlespeed & Fixed Gear - MKS Chain Tensioners

Don't worry, not another "how much do you love/anti-love these wares" thread.

Just had a question regarding the "sized for aluminum" units. Even oversized, the pocket in the tensioner is not wide enough to accomondate the frame fork end + aluminum insert. Is it safe to run them just contacting the edges of the fork end, or should I look at shaping them to drop into the tensioner. The MKS itself appears to be cast, so I think it might be easier to grind the "soft" aluminum pad (read: replacable mounting surface in the fork ends) in order to make it fit.
I guess all this boils down to is: has anyone tried re-shaping the MKS tensioner (wide one) to fit "extra-wide" aluminum fork ends, or is it not worth bothering (and just running them as is).

An associated question, does the eyelet in the tensioner run between the hub and frame, or frame and nut? I can see in the later that it would be significantly more important to have a nice snug fit with the tensioner, given that if it slipped you'd lose a bunch of chain tension in a hurry (the eyelets are not serrated like track nuts are). I guess the hub locknuts are serrated as well, so perhaps the point is moot. I've worked with BMX style tensioners before, and it's quite obvious they need to be on the outside, but with these going down the middle of the fork end it's a bit ambiguous.

Cheers!

so long as they are held on the actual fork end ends, you should be fine. if you have your tensioners under enough stress to cause problems on aluminum, you are misunderstanding their purpose. they are largely intended for 'dialing-in' your chain tension - not so much holding that tension against the stresses of riding. that is the purpose of, naturally, the track nuts. that said, they can help against minor slippage, but when they do that, they still aren't under much force -- they are just counteracting the little bit that the track nut/fork end interface isn't dealing with (in a slipping situation). this is all to say that you shouldn't worry about it. it would be dumb as hell to modify your frame (ends, etc) to accomodate a tensioner.

the keirin setup is to have the eyelet on the inside -- keirin frames are spaced accordingly (112-113, 122-123). naturally, your aluminum frame probably doesn't do this, so you can put them withever way works. i would tend to put them on the inside, still, because i wouldn't want to be torquing my track nuts against anything other than the ends themselves.

so long as they are held on the actual fork end ends, you should be fine. if you have your tensioners under enough stress to cause problems on aluminum, you are misunderstanding their purpose. they are largely intended for 'dialing-in' your chain tension - not so much holding that tension against the stresses of riding. that is the purpose of, naturally, the track nuts. that said, they can help against minor slippage, but when they do that, they still aren't under much force -- they are just counteracting the little bit that the track nut/fork end interface isn't dealing with (in a slipping situation). this is all to say that you shouldn't worry about it. it would be dumb as hell to modify your frame (ends, etc) to accomodate a tensioner.

the keirin setup is to have the eyelet on the inside -- keirin frames are spaced accordingly (112-113, 122-123). naturally, your aluminum frame probably doesn't do this, so you can put them withever way works. i would tend to put them on the inside, still, because i wouldn't want to be torquing my track nuts against anything other than the ends themselves.

Thanks for the info.

Well, held on is a relative term I guess. The MKS style are meant to cup the entire fork end. Given that mine are a mm or so too wide, they rest half-on, half-off. Agreed, if they're only dialing in the tension until the trakc nuts are snugged down, then it's really just a matter of asthetics. My only concern would be setting up a weird stress-state in the tensioner if the wheel slips and the tensioner starts to twist because it's not fully seated. Hmm..perhaps it's vice/file time for that thing...

Alright, so inside it is (makes more sense to me), given that the eyelet diameter is about the same size as the hub locknut, and not nearly as large an OD as the serrated track nut.

i wouldn't want to be torquing my track nuts against anything other than the ends themselves.

I torque my tracknuts on everything. Anyways inside the frame works best for me. Just make sure you don't break em they're kind fragile and tend to split in half.

Here is someone who carved out his MKS chain tensioners with a dremel tool:


http://128.83.80.200/bike/fixiedetail2.jpg



http://128.83.80.200/bike/fixiedetail3.jpg

Ti Fix (http://128.83.80.200/bike/tifixie.html)

"I also started running an MKS tugnut, which -is- color coordinated, on the drive side. It's a nice minimalist piece of kit and allows almost vernier adjustment of chain tension and wheel alignment.

The only drawback is that they're made for narrower steel forkends. I resolved the fit issue on my fatter ti forkends by carving out the inner wall of the chaintug with a dremel tool. They probably should have been made that way in the first place since it doesn't affect function in the slightest while allowing them to work on any forkend."

I personally have used the MKS tensioners both on the inside and outside. The inside makes more sense, but be forewarned they may be a real ***** to get off. My mechanic griped at me about how hard and how much work it was to get the tugs off the axle. For now, I use them on the outside as in the pictures above.