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RADBMX.CO.UK  |  Technical & Reference Section  |  Tech and Restoration  |  Chuffin' brake!
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Author Topic: Chuffin' brake!  (Read 1282 times)

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Voodoocars

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Chuffin' brake!
« on: May 08, 2007, 10:19 PM »
I've got a Mongoose Pro (about 5yrs old) that I saved from the crusher.Its only got a rear brake on it-not sure of the type-possibly 'U'.Brake caliper is in two bits each pivoting on a pin welded to the frame.Anyway,I cant get the bugger to work properly.Cables are free.gyro is smooth and everything is adjusted correctly but the blocks dont seem to grip the rim.Talk about brake fade! I've tried two different sets of blocks that are new and still no good.It seems like there is no friction between blocks and rim.Any ideas? Should I ditch the gyro to get a more direct cable action? Ian

rarman1

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Re: Chuffin' brake!
« Reply #1 on: May 08, 2007, 10:29 PM »
i doubt if the gyro itself is faulty but a knackered cable wont help, when you pull the brake does the free part of gyro touch the underside of the stem !

if not how much travel is there in the cable when the brake is pulled !, if theres not much then try a new lower cable

 ;)

Voodoocars

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Re: Chuffin' brake!
« Reply #2 on: May 09, 2007, 08:04 AM »
Brand new cables.Lever is off a Ruption but is still Tectra-but it don't have a very positive feel to it.Its doing my head in, just seems like the pad/rim has no friction.Strange!   

Offline harris

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Re: Chuffin' brake!
« Reply #3 on: May 09, 2007, 08:08 AM »
have you pre loaded  the brake springs..

theRuler

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Re: Chuffin' brake!
« Reply #4 on: May 09, 2007, 09:19 AM »
where is the straddle cable situated? put it IN FRONT of the seat tube

are the upper cable lengths too long and at an awkward angle?

low quality calipers and levers will flex, taking power out of a brake setup. and if that setup is weak because of the above it will stop it working right

Offline TwoBobRob

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Re: Chuffin' brake!
« Reply #5 on: May 09, 2007, 08:13 PM »
Gyros and bare alloy or coloured rims can be crap.....  Take all of the advice here, but I would also check the following;

1.  Look at your top gyro cable.  Where two cables become one, there is an adjuster. You also have an adjuster on your lever. Now, if you adjust these all the way out you can actually 'top out' that cable. That is to say the lead block inside hits the top of its housing and will move no more. So no matter how hard you pull the lever, nowt is happening at the other end. You're simply stretching the top cable of your upper gyro cable.  So wind those adjusters all the way in for now, if they're out.

2.  Make sure your gyro floating part  (the bit that spins) is slammed all the way down onto the tabs when you're not pulling the brake. If it isn't, sort the cable out to make it so.

3.  Only ever make your final adjustments with the single cable adjuster that is nearest to the actual brake.

4.  Now you can go back to the lever and remove any free play you might have with the adjuster there.  Free play only though.



I think we could all bang on for hours about gyros and brakes, we all have our ideas I think. But everything here should help  :)

Voodoocars

  • Guest
Re: Chuffin' brake!
« Reply #6 on: May 09, 2007, 08:59 PM »
All of the cable movement is ok with no cable joints toppping out.The lower part of the cable(s) to the caliper I had replaced with cheapo cables.There are actually two cables that run from the bottom of the gyro to the caliper as you may know if you are familiar with a mongoose pro.I'm going to experiment with lined outer cables and teflon coated inner gear cables as recomended by a friend who owns a bike shop.I'm swapping levers as well so we will see what happens.Bit of a 'project' really.He also recomended some pads that were transparent and really soft-but I'll wait and see first.Interesting.

Offline TwoBobRob

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Re: Chuffin' brake!
« Reply #7 on: May 09, 2007, 10:09 PM »
Yeah,  I've heard of a few riders running inner gear cable for their brakes. Works well apparently.  Soft brake blocks is a good call.  One thing to remember though - as a grown man these days your hands should be strong enough to overwhelm most any cable issues. If nothing is topping out, your rims are clean and the blocks are decent then you should be able to lock that wheel.

I've only ever ran chrome rims so I can't tell you, but someone on here should be able to reccommend a good block for alloy or coated rims (if thats what you have).

I'm assuming all the cables are oiled?  Finally  (and most obviously), if you aren't hankering after owning a gyro then chuck it and run a conventional cable, something like a Linear. That should end all of your problems   :)   Sometimes things are just more hassle than they're worth...

bof

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Re: Chuffin' brake!
« Reply #8 on: May 10, 2007, 07:07 PM »
make sure its not a v brake lever, it wont work on a U brake.

Voodoocars

  • Guest
Re: Chuffin' brake!
« Reply #9 on: May 10, 2007, 07:39 PM »
Thats odd- it was off a v brake (bought new levers now).Whats the difference between them? Ian

theRuler

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Re: Chuffin' brake!
« Reply #10 on: May 12, 2007, 07:52 PM »
i run black wheels and dia compe blocks (the ones that come with the hombres) and they are stop on a dime

v brake levers have a longer pull iirc

don't work with 990's

Voodoocars

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Re: Chuffin' brake!
« Reply #11 on: May 13, 2007, 08:03 AM »
Sorted ! Old lever did feel strange.New brake lever and teflon coated gear cables thru lined outers.Smooth operation.I can do a skid now! ;D

theRuler

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Re: Chuffin' brake!
« Reply #12 on: May 13, 2007, 12:13 PM »
get some backhops done

Offline TwoBobRob

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Re: Chuffin' brake!
« Reply #13 on: May 13, 2007, 12:24 PM »
Happy days   :)

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