Need help with IGH chain tension..
11-12-12, 05:17 PM
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Need help with IGH chain tension..
So I bought a MEC Chance commuter bike with an Alfine 11 internally geared hub.
https://www.mec.ca/AST/ShopMEC/Cyclin...cle-unisex.jsp
When I got it the chain seemed to be tensioned almost perfectly. Since then I've ridden about 500 kilometers and the chain has begun to sag a bit. In the picture below I've used string to show how much sag the chain has. It's about half an inch. It looks easy enough to tension. The rear hub drop outs are on metal slides that ca be adjusted forward or backward to tension the chain.
I'm just wondering if the chain even needs to be tensioned. I've read that chains don't actually stretch and it's so new that I'm confused how it has begun to sag.
Any advice is appreciated.
https://www.mec.ca/AST/ShopMEC/Cyclin...cle-unisex.jsp
When I got it the chain seemed to be tensioned almost perfectly. Since then I've ridden about 500 kilometers and the chain has begun to sag a bit. In the picture below I've used string to show how much sag the chain has. It's about half an inch. It looks easy enough to tension. The rear hub drop outs are on metal slides that ca be adjusted forward or backward to tension the chain.
I'm just wondering if the chain even needs to be tensioned. I've read that chains don't actually stretch and it's so new that I'm confused how it has begun to sag.
Any advice is appreciated.
11-12-12, 05:48 PM
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You are basicly correct in that the metal the chain is made of has not stretched. But each link has a bushing/bearing at each end and these do wear. Even a tiny amount of wear in each bushing vwill add up after almost 100 units. Additionally the cog and chain ring will wear a bit allowing the chain to settle into the teeth a little bit more. If you keep your chain clean and lubed then this wear will be initially faster then seem to slow down. This is just one of the reasons that a bike should be returned to the LBS for a tune up after a few hunderd miles. Andy.
11-12-12, 06:01 PM
#3
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+1 The chain doesn't physically stretch, but gets longer as the inner parts wear out. In any system without a derailer (fixed gear, single speed, IGH) there shouldn't be any actual tension in the chain but rather it should spin as smoothly as it would if it were slack. Then take out as much slack as possible without actually making it tight. I'm probably not describing this very well but hopefully that makes sense.
I would change that to: This is just one of the reasons it's nice to know how to work on your own stuff when adjustments and problems arise.
Originally Posted by Andrew R Stewart
This is just one of the reasons that a bike should be returned to the LBS for a tune up after a few hunderd miles.
11-12-12, 09:14 PM
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To built on Fast Jakes post. There shouldn't be any chain tension at all. The standard test for correct (non)tension is to move the center of the lower loop up and down. It should be free to move about 1/4" either way.
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11-13-12, 02:33 AM
#5
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Year around riding, I get a year out of a chain [53:16 turning a 20" wheel]
Larger wheel Circumference may not be same since 1 rotation covers more ground.
Larger wheel Circumference may not be same since 1 rotation covers more ground.
Last edited by fietsbob; 11-13-12 at 02:36 AM.
11-13-12, 05:55 AM
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You have sliding dropouts on the frame. Loosen the bolts, ease the dropouts back a bit, then tighten back up. Then you will probably need to adjust the shift cable. I don't know how to do that on an Alfine, but I would start by looking up Shimano's website.
11-13-12, 06:04 AM
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Originally Posted by DieselDan
Then you will probably need to adjust the shift cable.
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11-13-12, 06:36 AM
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Thanks for the responses guys. Although I have a year of free maintenance included on this bike I have to drive an hour or more to use it. Aside from that though, I like to do my own maintenance wherever possible. To reiterate, I'm pretty sure I can adjust the chain tension with ease, I just wanted to double check if it was even necessary. As for adjusting the IGH shifter cable, that's easy and takes only a few seconds. I think I'll double check my measurements and give the adjustment a go myself.
11-13-12, 07:15 AM
#9
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That is not excessive chain slack. You have chain guides on both the chainring and the cog, so it's not going to throw the chain. Ride it and be happy. (But make sure the sliding dropout bolts are tight.)
11-13-12, 07:33 AM
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Since the cable stop at the hub end is part of the hub assembly which moves with the wheel when adjusting chain slack, why will shifting or shift cable tension need to be adjusted as well?
When adjusting chain slack, check while you're doing it by rotating the crank through a couple of revolutions. Neither the chainring nor the drive cog are perfectly round and static adjustment at any one point may mean too loose or too tight at other parts of pedal revolutions.
When adjusting chain slack, check while you're doing it by rotating the crank through a couple of revolutions. Neither the chainring nor the drive cog are perfectly round and static adjustment at any one point may mean too loose or too tight at other parts of pedal revolutions.
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11-13-12, 09:25 AM
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Originally Posted by mconlonx
Since the cable stop at the hub end is part of the hub assembly which moves with the wheel when adjusting chain slack, why will shifting or shift cable tension need to be adjusted as well?
When adjusting chain slack, check while you're doing it by rotating the crank through a couple of revolutions. Neither the chainring nor the drive cog are perfectly round and static adjustment at any one point may mean too loose or too tight at other parts of pedal revolutions.
When adjusting chain slack, check while you're doing it by rotating the crank through a couple of revolutions. Neither the chainring nor the drive cog are perfectly round and static adjustment at any one point may mean too loose or too tight at other parts of pedal revolutions.
