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Chain jumps and jams behind block
#1
Help! I have a problem with my Claude Butler Majestic fitted with a Suntour Vx Gt rear deraileur. When I change to first gear, 9 times out of 10 it's ok, but about 1 in 10 of these changes results in the chain skipping right over the cog to get jammed between the spokes and the gear block. My spokes are already looking damaged! I've tried adjusting the stops; if I adjust it so I can just get first gear, it will jump on some of the changes. Planning a long tour to the south of France in 1 month, so I'[m needing a solution! the block range is 14 to 28 (I'd like a lower gear for those steep hills loaded with camping gear!). Front double chainring is 36/52.

I was wondering if a wider ratio block would cure this, as the jockey pulley seems a long way from the block, even in first gear?

Rok
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#2
- Readjust the dérailleur: set the limits, the cable tension and also the B-tension screw. look at the tutorials on this site, they are really helpful
- If dérailleur cannot be adjusted: check cables and housing
- if that is ok and the shifters are ok: how old is the dérailleur? Maybe the spring is worn.

If you plan a longer tour, replace the spokes! They will break soon (and at the most inconvenient time + place).
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#3
(11-01-2011, 09:45 AM)Joe_W Wrote:  - Readjust the dérailleur: set the limits, the cable tension and also the B-tension screw. look at the tutorials on this site, they are really helpful
- If dérailleur cannot be adjusted: check cables and housing
- if that is ok and the shifters are ok: how old is the dérailleur? Maybe the spring is worn.

If you plan a longer tour, replace the spokes! They will break soon (and at the most inconvenient time + place).

Thanks for the advice. I've already done all the adjustments, including the B tension screw. The changer seems to be in mint condition as is the rest of the bike. It takes up the chain tension with no problems.. not even any slapping on the chainstay!

I've also just replaced the chain, though the 'old' one didn't seem in bad condition. Chain ring and sprockets are all in good condition.
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#4
In view of your upcoming tour, I strongly suggest you visit your friendly LBS, have a critical look at the alignment of your Rd, it may be slightly bent! also get your wheel checked, it may need respoking, especially as you will be carrying a load, also have a spoke guard fitted, this will reduce damage to the spokes.
Join the CTC; http://www.ctc.org.uk/
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