Edit derailleur fixed just need brake advice

[imrealymad]

Edit Derailleur is working now just need to figure out the rear brakes. The rear v brake is touching the rear tire because it is not centered to frame any advice on fixing it?


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Ok the stock rear derailleur on my 1998 Trek 930 (http://www.bikepedia.com/QuickBike/BikeSpecs.aspx?Year=1998&Brand=Trek&Model=930&Type=bike) aint gonna work.
I adjusted it all over but cog on the deraileur it self is touching the freewheel and cant be adjusted to not touch. This is with a 9C 2806 from ebikes.ca . Combine that with the fact that with the fact that the wheel is far enough from centered that I cant use the v-brakes with it. Should I get a different rear deraileur and run with no rear brakes? If so what kind?
Or should I just get a newer bike with disc brakes. Was looking at some Motobecanes because of the price. This is just for commuting to work and errands not for off roading.
I was looking at these 2 bikes
http://www.bikesdirect.com/products/motobecane/motobecane_400HT_x.htm
http://www.bikesdirect.com/products/motobecane/motobecane_600HT07.htm
What do you think do these look like they would be good enough for commmuting purposes?

 

[vanilla ice]

What is touching the freewheel? Did you try different chain lengths? Is it one of those mega 34 tooth freewheels with a short cage RD?

 

[imrealymad]

Well it was the small cog on the rear derailleur tha was touching what ever gear I shifted into on the rear freewheel so that the chain was being pinched in between the two.However as soon as I tried to pedal it just now the chain broke and I lost one of the links. so I loosened every thing back up and now the derailleur will work heh. Now I just have the problem with the rear brakes to work out.

 

[vanilla ice]

Right, if you have too many links in the chain the freewheel will rub the jockey wheel cage..

 

[amberwolf]

Is the rear axle bent? This will cause the entire wheel to be off-axis and the wheel will always rub the same part of the bike all the time.

Or is the rim out of true? This will cause the wheel to appear to wobble and the same part of the rim will rub anywhere on the bike that is close enough to it, while rotating around. But it won't always keep rubbing the same spot (like the brake), just when the bent part of the rim rotates around to that spot.

Alternately, is the brake arm itself bent? Or it's mounting point (the stud on the frame) or the frame itself?

Or, if your brake arms have external springs that parallel the arms, like the ones on the right:

then the spring might have popped loose from the end of the arm, as mine sometimes does when I have the wheel off the bike (but never in use so far).

 

[imrealymad]

I have the wheel mounted and it spins perfectly fine, no wobble and not bent. when looking at it from behind it is just a little to far to the left of the frame not centered with the rest of the bike.I get on and peddle around and it feels just fine but I can't figure out what to do about the brakes. Even loosened up the brake pad on the left was hitting the rim all the time. I think maybe I can spread the frame and put some spacers on the left side of the wheel inside the frame on the axle and it might work. Now I just need to find some spacers.

 

[amberwolf]

If it is actually shifted over to one side, then I'd guess the whole frame is bent in that direction at the dropouts. Probably from the impact that did in the derailer. Usually this results in a wheel that is angled; I'm not sure why it would not do so in your case if indeed the frame did bend. But I cannot think of anything else that would shift the whole wheel over to the left that also matches with the rest of what happened.

If it is an aluminum frame I do not recommend spreading it. It could cause stress fractures in it, especially if it has already been bent from the crash.

If it's steel, it should be fine to spread it and then use spacers.

 

[imrealymad]

Well bike has been sitting in my shed for probably 10 years. Never been wrecked. The factory wheel was lined up perfectly. The 9C hub motor is not. it is off to the left side of the axle to far I believe. Frame is Cromoly. Shrug. I think I will try the spacers and hope for the best.

 

[amberwolf]

Oh, ok. I must be confusing this bike/thread/etc with a different one. I thought this one had been thru a crash that needed fixing. Sorry about that.

I didn't see the previous part of the thread about the hubmotor in the wheel or I would have suggested that it needs to be either spaced differently with washers (as you already want to do) or relaced to sit differently in the rim.

There have been some problems with some hubmotors not being able to be dished correctly due to the spoke flange positions and the large diameter of some motors (like the 9C). Some of them, even with all the spokes on the outside of the right flange, and dished totally flat at that point, still do not put the rim centered in the frame, and it is still offset to one side.


The only easy way to deal with the brake issue I know of is if you have brake pads that use those bevelled/rounded washer stacks to position them. Those stacks have (from brakepad outward) a thin flat washer, a thicker concave washer, a thinner convex washer, then the brake arm, and then a thinner convex washer, a thinner concave washer, a thin flat washer, and the nut. Sometimes you can rearrange the order of these so the thinner concave washer is on the inside and thicker on the outside, to allow the brake pad to clear a wider or offset rim. You might have to put both of the thin flat washers, plus perhaps a third one, on the other brake pad that is too far from the rim to help it reach the rim properly.

 

[imrealymad]

Well my ping battery should be here today, spacers later this week hopefully. So I'll find out soon enough if this whole setup will work or not. Thanks for the idea on the brake washers, will give that a try if the spacers arent enough.