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Old 08-22-08, 12:40 AM   #1
ilnn
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Track End Chain Tensioner?

Hi, I'm new to track bikes and i just ordered an iro bike, but i am concerned with chain tensioning.
i have seen bmx style chain tensioners on track ends, but can someone explain how it works and how it is installed in layman's terms?
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Old 08-22-08, 07:44 AM   #2
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the chain tensioners goes on the axle of the wheel, the wheel goes into the frame, the tensioners has a block with a strew witch push against the frame to hold tension on the chain and you tighten the axle's nuts.
you can change the tension on the chain by adjusting the strews.
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Old 08-22-08, 07:51 AM   #3
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kinda difficult to explain clearly without a diagram, but they're pretty self-explanatory once you see one up close
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Old 08-22-08, 09:16 AM   #4
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Track chains should not be under tension. They should be at least a wee touch slack at all points of crank motion.

Devices to hold the rear wheel position already exist. They are called axlenuts. Seriously, unless you're taking up sprints and kilo because you were just cut from the 49ers offensive line, the rear wheel ain't going to move.

If the rear axle is moving under load, you likely have a frame or hub problem. Or you didn't tighten it enough. Most use the 'peanut butter' wrench. It's about 7" long IIRC. Really doesn't take much.
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Old 08-22-08, 07:03 PM   #5
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Track end chain tensioners are neither to hold the chain in tension, nor to hold the rear wheel in position.

They're so when you take the wheel off (say, to fix a flat) you can immediately put it back in the correct position when you remount it without needing to go through the whole adjustment routine again, cause the tensioners are still set to where they were before you removed the wheel.
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Old 08-22-08, 07:17 PM   #6
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Originally Posted by melville View Post
Track chains should not be under tension.
...

All chains are under tension, by the very fact that they are on the bike.
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Old 08-22-08, 07:19 PM   #7
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Originally Posted by ascend View Post
Track end chain tensioners are neither to hold the chain in tension, nor to hold the rear wheel in position.

They're so when you take the wheel off (say, to fix a flat) you can immediately put it back in the correct position when you remount it without needing to go through the whole adjustment routine again, cause the tensioners are still set to where they were before you removed the wheel.
Completely and utterly wrong.
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Old 08-23-08, 02:06 PM   #8
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still confused
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Old 08-23-08, 02:25 PM   #9
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http://www.63xc.com/rickc/tuggnuts.htm
cleared it up a little
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Old 08-23-08, 05:50 PM   #10
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Completely and utterly wrong.
Ok then tarzan, why don't you explain to us all what they're for then instead of just swinging through and pointing out whose wrong. We could be here all year if everyone takes a shot and then awaits your unhelpful criticism.
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Old 08-24-08, 05:53 PM   #11
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We are talking about track bikes. I think generally your description is probably applicable to say BMX bikes or fixies. Why doesn't it apply so much to track bikes? Cause you are fairly constantly changing your gearing. Either by swapping out the front chainring or using a different rear cog, or both. This negates a chain tensioner from being useful in setting constant tension for wheel changes and the like.

Generally they are of negligible benefit on a track bike. In fact the only people I see using them at the track, are those who have frames where the tensioners are actually built into the frame.

There are two benefits of using them:

1) It allows you dial in a desired tension (which maximum should be slack enough that you can move the chain 15mm+/- from the centerline in the middle of the chain), then maintain that exactly, and keep the wheel perfectly straight in the dropouts while you are wrenching the axle nuts. Having said that it's not all that hard to do this without the tensioners.

2) Some frames (especially those without stainless dropouts) don't always allow for the wheel to be held as securely in place. So you occasionally see a pulled wheel in non rolling start events, eg kilo. Tensioners eliminate the possibility of this.

--brett
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Old 08-24-08, 06:28 PM   #12
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Originally Posted by operator View Post
...

All chains are under tension, by the very fact that they are on the bike.
On bikes with rear derrailleurs yes. But on a track bike you want the chain to be under no tension but with as little slack as you can manage. Any appreciable level of tension beyond that produces drag in the system and is hard on the chain and sprockets for no reason.


With that in mind the idea of the tensioners as locating devices fit in just fine thankyouverymuch.
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Old 08-24-08, 08:37 PM   #13
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On bikes with rear derrailleurs yes. But on a track bike you want the chain to be under no tension but with as little slack as you can manage. Any appreciable level of tension beyond that produces drag in the system and is hard on the chain and sprockets for no reason.


With that in mind the idea of the tensioners as locating devices fit in just fine thankyouverymuch.
I'll keep riding while you try to put your chain back on after it fell off again.
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Old 08-24-08, 08:54 PM   #14
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I'll keep riding while you try to put your chain back on after it fell off again.
I've been riding my SS for around 7 or 8 years now using the roughly 10 to 15 mm of vertical play at mid point similar to what sideshow_bob said above. At the tight spots it just barely goes tight.

It hasn't fallen off yet other than one time on the parkade ramp when the QR skewer let the axle slip ahead and the wheel went all cockeyed. Changed to a solid axle and never had a problem since.

Try it and see how much less drag the drivetrain has.

Obviously this is one of those deeply religious issues similar to cleaning chains or the ideal tension for spokes. No one will change their mind one way or the other from this thread I'm sure.
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Old 08-24-08, 08:59 PM   #15
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I have chain tensioners on my single speed road bike. It's easier to get the right tension on the chain after taking off the wheel. I have to reset them everytime I put the wheel on btw.
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Old 08-24-08, 09:11 PM   #16
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I have chain tensioners on my single speed road bike. It's easier to get the right tension on the chain after taking off the wheel. I have to reset them everytime I put the wheel on btw.
I thought I had to do that too on my new Redline 925. But reading here on BF.net I learned that I only had to loosen the axle nuts more so the tensioners came loose and could swing out of the way. Of course that would depend on the design and amount of chain tension....

Found a couple of YouTube vids on tensioning.

I like to set mine up pretty much like this first one or perhaps a hair tighter at the tightest spot....

http://www.youtube.com/watch?v=Thb1UER1ous&NR=1

But I try to avoid this other extreme...

http://www.youtube.com/watch?v=YHka80Jqikc&NR=1

Copied from Sheldon's site on chain tension....

Quote:
Once you have the chainrings centered and secured, adjust the position of the rear axle to make the chain as nearly tight as possible without binding. Notice how freely the drive train turns when the chain is too loose. That is how freely it should turn when you are done, but with as little chain droop as possible.
I did it as told back when I started SS'ing and still do it this way now.

Last edited by BCRider; 08-24-08 at 09:18 PM.
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Old 08-25-08, 12:01 PM   #17
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do not use chain tensioners---- get used to setting the wheel by hand--- tension by feel-- torque by feel--- you will master this-- If you ride fixed on the street-- you need slack and you need to read your bike--Tensioners give the illusion that everything is OK and qwik--- I dont like that feeling--- nothings easy!
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Old 08-25-08, 12:15 PM   #18
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all the track guys that run the streets that I am familiar with--- I run a tight single speed chain--- they run a slightly slack chain--- use fresh tools for your track bolts and use a quality nut--- learn to tension on a stand and flipped over-- if your axels are allen bolts--- again, use the right tools- no slop--- if you are running without a brake-- oy, you gots to learn-- this is your life!
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Old 08-25-08, 12:31 PM   #19
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always check the threading on nuts and bolts and axels--- I am not a track expert---- I've built many ss's --
I would feel that chain tension should be "tight" enough-- no binding- I ride the streets--- bouncing and skipping-- I don't want the chain to come off-- I'd rather wear through a bb , a cog, a freewheel--- than fall--
running on a velo is not wilshire blvd! learn the tricks of the street and gear ratio, etc--- don't fool around--
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Old 08-25-08, 01:36 PM   #20
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It's relatively easy to determine the amount of tension on a track bike (fixed), as soon as you exceed the slack allowed (which is very little) a cranks' play is detected immediately, rather than a smooth circular motion. I have not measured deflection on my track bike but I'm estimating +- >10mm

Refer to Sheldon's article on fixed chains for addtl info.
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