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Old 06-05-08, 02:08 PM   #1
bikerjeg
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B screw too short now what?

I have been riding my new bicycle for the past week with my rear derailleur not properly adjusted. I am pretty sure it's a problem with the b screw since my hanger rides too close to the cassette and makes a convulsive click. It only happens when I am on the lowest gear. what are possible solutions to have my rear derailleur ride correctly? I have already tried flipping the B screw as was mentioned in a thread I found regarding similar issues but it did not give enough adjustment. Are there any other possible problems I may have that I am missing?

By the way my rear derailleur is a Shimano Sora

Thanks
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Old 06-05-08, 02:12 PM   #2
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What's your largest rear cassette cog?
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Old 06-05-08, 02:38 PM   #3
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Get a longer 4MM screw!
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Old 06-05-08, 05:20 PM   #4
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Originally Posted by Bill Kapaun View Post
Get a longer 4MM screw!
Yes, I agree.

It's really annoying when there are some new bike configurations where the b-screw is just not long enough to do the job, due to an improperly spec'd/matched/designed(???) derailleur hanger. If the lip on the hanger is not close enough to the end of the b-screw (or, too far away, if you will), then it's possible that you are not going to be able to tweek out the clashing of the jockey wheel and the cassette.

It really amazes me that bike manufacturers can't get something so simple right. I've seen this on several occasions and, at first, I thought it was some problem specific to one bike, but then I saw the problem track consistently on every single bike of the same specific model.

Bikerjeg, you should take your bike back to the dealer and hold their feet to the fire until they fix the problem. Make them show you an identical bike and prove it's not something common to all bikes of that type. If they can't fix the problem with a longer screw, have them upgrade your derailleur. If that does not work, have them contact the bike manufacturer and see if they won't upgrade your model of bike. It's unfortunate that the shops get stuck in the middle on a deal like this, but the shops should definitely pass the problem right back to the bike manufacturer and make them fix it.

It would be wrong for me to name specific models that I know of, but I feel that a new bike customer should not have to put up with bad design, and that the manufacturers should do what they must to satisfy the customer. This is a really dumb problem that I've seen on numerous occasions in the last couple of years. In the end, it's just very poor engineering.

Edit: It's also possible that the incorrect derailleur hanger was sent with the new bike to begin with. Again, that's the fault of the bike manufacturer.

Last edited by cascade168; 06-05-08 at 05:22 PM. Reason: more clarification
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Old 06-05-08, 05:26 PM   #5
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Another possibility is that your chain is longer than necessary. Shift into the big-big combination and see if there is still enough slack to remove one full link (i.e. two pins including an inner and outer set of plates or 1" of chain length). If so, shortening the chain should give you more clearance.

As above, that assumes the largest cog isn't way beyond the derailleur manufacturer's specs.
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Old 06-05-08, 05:51 PM   #6
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It really amazes me that bike manufacturers can't get something so simple right.
If you've spent any time building sub $1k bikes out of a box recently you'll be amazed the amount of stuff they get right vs the amount they get wrong is about 1000:1.

For example I pulled a brand new bike out of the box today with threaded fork that is cut too short.
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Old 06-05-08, 06:15 PM   #7
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If you've spent any time building sub $1k bikes out of a box recently you'll be amazed the amount of stuff they get right vs the amount they get wrong is about 1000:1.

For example I pulled a brand new bike out of the box today with threaded fork that is cut too short.
Oh, I agree that there are tons of individual problems. No doubt about it. But, what I am talking about are problems that are consistent from one bike to another, like this b-screw issue. That's not a one time problem, from what I've seen the last couple of years. And, these problems come from some very respectable manufacturers.
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Old 06-06-08, 04:26 PM   #8
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Quote:
Originally Posted by Retro Grouch View Post
What's your largest rear cassette cog?
28T

Quote:
Originally Posted by Bill Kapaun View Post
Get a longer 4MM screw!
I asked the bike shop and they gave me a real defeatist attitude as though they just wanted me to take the bike in to them to have it looked at. They said they didn't have the screws and that they didn't recommend flipping the b screw. They also told me it could be a problem with the spring inside the derailleur mechanism but I doubt that since the bike is pretty new.

I'm going to check at orchards or home depot in a while and see if I can get a screw that can settle this affair
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