Introduction: DIY Bicycle Chain Tensioner

Picture of DIY Bicycle Chain Tensioner

Chain tensioners and guides are often used in "extreme" mountain biking such as downhill, freeride, and fourcross. They are used to stop the chain from bouncing around and falling off. However, they are very expensive for a simple item, generally ranging from 30 to over 100 euros. This is a simple way to make one that costs almost nothing  and you probably already have the materials! Also, chain tensioners can usually only be used with one or sometimes two front chain rings. This one works with three!

Step 1: Materials

Picture of Materials

1) Rear Bike reflector

2) Small piece of garden hose

3) Ziptie(s)

4) Scissors or something else to cut with

5) Phillips Head Screwdriver

Step 2: Take Apart the Reflector

Picture of Take Apart the Reflector

Take out all of the nuts and bolts from the reflector. You can discard the reflecting piece but keep the rest as you will need to put some of it back together.

Step 3: Add the Hose

Picture of Add the Hose

Take the piece of hose and put it on to the round part of the reflector. It will not fit on easily so I recommend either putting it in boiling water or holding it under a small flame (quickly - don't burn it!) to make the process easier. It only needs to cover the plastic circle so trim the hose if it is too big.. I had already made my tensioner so I didn't put the hose on the whole way because I still needed that reflector.

Step 4: Attach the DIY Chain Tensioner

Picture of Attach the DIY Chain Tensioner

Place your new chain tensioner so that your chain runs through the circle and reattach the nut and bolt. You can choose to attach the second piece of the reflector. If you do this, you can attach the tensioner more securely but your chain will not be pulled up as much. Now all you need to do is ziptie it on through the remaining hole or holes in the reflector. The picture shows where to put the zipties through. Ziptie the tensioner to the chainstay on your bike (the bar above the chain). Make sure that you do not put it too close or too far away from the front chainrings. Use the pictures of my bike as a guide.

Step 5: Finished!

Picture of Finished!

You are now finished with your DIY chain tensioner - Go try it out! It should help your chain stay in place for a long time. When the hose eventually wears out, all you have to do is stick on another piece and ziptie it back on!

Thanks for reading my Instructable; I hope you liked it!


sidmarx (author)2015-12-14

Have you tried something similar but using a jockey wheel from a derailleur? That was my idea, but i haven't found out how to hang the j. wheel so it turns. I can't use the stock derailleur cage as the thing is riveted fast. Using the whole derailleur on a single speed doesn't work since the freewheel teeth & SS chain are too wide.--the detachable link jams, etc.

PeterM505 (author)sidmarx2017-11-23

I made a tensioner today using a jockey wheel and reflector mount. The jockey wheel was stolen off a tensioner that I got for a SS conversion a while back but is the same as one off a derailleur; it bolted onto the arm so I used the same bolt for my DIY.

I did need to construct an arm out of some scrap aluminium I had lying around so the jockey wheel didn't catch the reflector mount. The wheel spins smooth and works really effectively; thanks for the inspiration GuitarGuyJames!

paspoi made it! (author)2015-10-25

just made it ... need to try it now!

FileBravo (author)2014-10-22

Great! I like to see the face of the mechanic when he finds pieces of diy on my bike:-)
I can grant that this solution is really robust. I made it on my trek. Pictures with my phone are quite dark...

Iw-Munt (author)2013-04-16

Love it! Hope it will be OK with my SS project, if not I'm gonna stick it on my xc bike. Thank you

Zsombee (author)2012-10-11

instead of garden hose, i'd like to use inner tube - is it a good idea?

GuitarGuyJames (author)Zsombee2012-10-12

Eh, I would recommend the garden hose for two reasons:
1) More durable, and
2) More slick.
The innertube would probably work, but there would be more friction and it could wear down. So... if you have garden hose, use that. If not, use the innertube.

tutdude98 (author)2012-08-08

How do you make chainstay protector?? is that old innertube

GuitarGuyJames (author)tutdude982012-08-09

Yeah, I just cut open an innertube, wrapped it tightly around the chainstay, then ziptied it on.

tutdude98 (author)GuitarGuyJames2012-08-09

when i broke my rear derailleur it was scratched down the protective film :P so i need to make something like this

GuitarGuyJames (author)tutdude982012-08-09

Use this website but you don't need to take the wheel off.

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