Why did the chain on my kid's bike slack after I changed his tire?

Question

I changed the rear wheel on my child's bicycle today. Once I was done and put it back together, the chain is inexplicably longer; there is a lot of slack.

How did this happen and how do I resolve it?

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Edit: looking at the photo, I think I may have to move the rear axle backwards.

Edit x2: Photo of successful results, following my suspicions and Paparazzo's answer.

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The frayed end? Came unraveled a bit when I was loosening it so I could take the wheel out. I twisted it a bit more into itself after the photo was taken. — JoshDM, Jun 16 '14 at 14:27

paparazzo · Accepted Answer · 2014-06-15T17:21:13.407

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Move the wheel back in the dropout. Equal on both sides. Go for 1/2 to 1 inch of play in the chain.

And that valve stem might be leaning a bit. Probably not enough to matter but ideally it is straight.

edited Jun 15 '14 at 17:21

answered Jun 15 '14 at 17:10

paparazzo

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Amateur here. The dropout holds the rear axle? – JoshDM Jun 15 '14 at 17:10
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Yes the dropout holds the rear axle. – paparazzo Jun 15 '14 at 17:11
OK, that worked. – JoshDM Jun 15 '14 at 17:18
I'll deflate and redo the stem. – JoshDM Jun 15 '14 at 17:23
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Like those "spot the difference" photographs! – PeteH Jun 15 '14 at 17:55
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Check the position of the brake pads as they seem to 'bite' into the tyre. – Carel Jun 15 '14 at 18:45
@Carel - Should they bite into the tire or the rim? – JoshDM Jun 15 '14 at 19:52
Rim. No brake on rubber. See Sheldon Brown. – paparazzo Jun 15 '14 at 20:02
The rim would have eventually cut into the valve stem if you'd left it like that. – DWGKNZ Jun 15 '14 at 23:22
I deflated the tire, pulled the stem further out and straight, then re-inflated. – JoshDM Jun 16 '14 at 00:16
Pulling it out does nothing to align. You need to move the tire. Just deflate and pull on the tire. You may need to pull at many points on the 360. – paparazzo Jun 16 '14 at 00:25
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The brake cable looks frayed. Replace & put on a proper end-cap. May cause nasty wounds! – Carel Jun 16 '14 at 07:14
The easiest way to adjust the inner tire is to have the outer tire loose, then inflating the inner tire just a bit. That way you can easily put it in the correct position. Then put the outer tire on, working away from the valve on both sides of it. – SQB Jun 16 '14 at 07:24
As noted in the comments to the question post and elaborated here, I took pliers and twisted the frayed end into itself so it's near normal and won't scrape. I'll take a look at shifting the inner tube again later. – JoshDM Jun 16 '14 at 14:29
They have crimps for the cables. I just use electrical crimps. – paparazzo Jun 16 '14 at 14:45

score 7 · Answer 2 · edited Mar 09 '17 at 18:04

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It seems you're missing the 'tensioners'^‡. They go on each side of the axle with the cap hooked on the end of the dropout. You can then adjust the tension of the chain by fastening or loosening the nut on the end (first loosen the axle nut, of course).

^{Chain tensioners by 1-1111.}

Not all bikes have these, though.

^{‡: I couldn't find the correct translation, but their Dutch name would translate to "chain tensioners".}

Additionally, you usually can see where the axle used to be by the markings on the dropout.

edited Mar 09 '17 at 18:04

Community

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answered Jun 16 '14 at 06:35

SQB

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Chain tugs is another term. – May 26 '17 at 13:51

Why did the chain on my kid's bike slack after I changed his tire?

2 Answers2