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Chain Too Short?
#1
Old 7Speed Cruiser (Sun Retro-7). Original rear wheel had 28-14 tooth freewheel. Newer rear wheel has 28-11 tooth cassette.
Everything looked fine until I put a new chain & cassette on it.
The old chain had 118 links, the new KMC x8.93 has 116, you can really see it it the orientation of the rear derailleur.
1st gear
[Image: 1stGear.jpg]

3rd gear
[Image: 3rdGear.jpg]

7th gear
[Image: 7thGear.jpg]

1st gear rear derailleur orientation used to look like the 3rd gear picture above. New cassette identical to the old, only the chain is different.
This looks like I'm going to have rear derailleur problems.
1) Does somebody make a good longer chain?
2) Do I need to forget about it & just ride it? I do 300+ miles/month.
  Reply
#2
Looks like the RD still has quite a bit of travel left, so should be okay.

You could check the recommendation of the many online chain length calculators; here are some:
http://www.epicidiot.com/sports/chain_length_calculator.htm
http://www.machinehead-software.co.uk/bike/chain_length/chain_length_calculator.html
http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html

I follow Shimano's recommendation: wrap around the big cog and big ring and add a full link (1").
Nigel
  Reply
#3
[align=right]I've seen Shimano's diagram which is about a straight line down the center of the axle & the two idler wheels in 1st gear. This looks ok to you, you wouldn't worry about it?

Park Tool says:

"Inspect chain for "S" bend as it passes through pulley wheels". If it is near straight it's no good. They say to check it during the shift from 2nd to 1st also.

They show this picture as OK.

[Image: chain-OK1.gif]

I'm a little concerned, it just looks "strained" to me. I would guess they would know.
  Reply
#4
Yeah, I have had that feeling also from the first time people told me that this was how to do it. However I recently found
http://www.slowtwitch.com/Tech/Chain_How-To_-_Part_1_3279.html
His method leaves the chain as long as possible, enabling you to swap the cassette for one with a bigger large sprocket.
  Reply
#5
Yes, he also shows pictures with the rear D pretty extended in low gear. I am more accustomed to my one chainring bikes rear D looking like the bottom left photo, except with the chain on 1st gear! My bike has a super cheap rear D & I'm a little concerned that it may fail.
[Image: 60208-largest_Cage_Sequence_Full.jpg]
  Reply
#6
If 116 is the longest common chain what do tandems & Electra townies use?
  Reply
#7
Hi Jeff;

On our Trek T50; the chain to from the rear cranks to the cassette is now (brand new) 114 links, with 11-34T cassette and 26-44-54 rings at the front. With the SRAM X9 RD, it works fine in 54-34 combination and 44-11; I need to adjust the FD to get into the granny ring.

The timing chain (between two set of cranks) is made up two chains.

SRAM chains are usually 114 links (58").
Nigel
  Reply
#8
(04-13-2013, 08:33 PM)nfmisso Wrote:  SRAM chains are usually 114 links (58").
I wonder what "pedal forward" bikes use when it comes to chains?
  Reply


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