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Grind , Brake Problems


the mysterious leemur

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:blink: Bit of a weird thing going on atm....

Bought a new frame recently and decided to run it with a 05 maggie , 4 finger lever , LGMs and a TNN booster and clamps all on an Echo TR rim.

I ground the rim using a stone cutting disk ( wore through my metal one ) and I've been of the though that thicker disk meant harsher grind? Any way after grinding the rim ( not my best I will admit ) and squaring the pads the brake was awesome and I really mean it , miles better than any other brake I have felt or used , incredible noise , mindblowing bite and amazing hold.

Problem is now , two days after the brake has much much less hold , little bite (similar to my old plastic hs yellows) and little sound.

I have noticed the grind has become quite smooth and smoother than my 24 Echo rim which was ground 2-3 months ago...

I really have no idea what has happened here , any help or an explanation would be great. :blink:

*Also has anybody else had issues with TNN clamps making the slave sit at an angle when tightened?*

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The sharper the disc you use the harsher the grind. I use a cutting disc and work it against steel to sharpen it before each use.

As for the tnn clamps the best thing to do (this goes for pretty much any clamp set up really) is to remove the brake and rear wheel, and run a file across the frame's mounts... There's a detailed video of how to do it on the tnn site I believe. You won't regret the effort. Work diagonally accross the mounts with little pressure on the file, hold it in the centre. You will be able to see when all mounts have been filed flat.

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Some rims will go smooth really fast like rockman singlewall, but then trialtech rims have execellent quality and hold grinds for weeks. If it was a new rim and first grind, try to grind it few more times, if it still dont hold grind, then... the rim is just crap >_<

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It's probably a result of how you ground your rim. Chances are the brake was amazing at first because the different method created a few spread out and/or really sharp points on the grind. Being sharp and/or spread out these points will dig into the pad really well, and give amazing bite. Trouble is, if they're sharp then the tip of them isn't supported as well as a blunt point would be, so will blunt easily, and if they're spread out too, then each point is taking more load, again, causing it to blunt easily.

Paint has provided me with a shonky simplified diagram to explain my point:

post-4312-0-65704000-1341910689_thumb.pn

The top one will bite amazingly, but wear very quickly, while the bottom one will be less impressive to start off with, but will hold it's sharpness much longer.

I'd suggest going back to your old method of grinding if that worked for you, or following tutorials if you're wanting to try and improve on it.

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I concur, personally I fekin hate grinding rims, its so boring so I let them get really shite before a regrind, this usually takes months.

Had a mate grind mine this time because I could not be arsed and its the best grind I have ever had, some people are just good at it, some are shite, I think I fall in the middle.

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I'll try get some pics up soon , I think the problem is what RobinJI suggested or just it being a bad grind , think it was probably too light or something like that as it is so smooth already . I'v filled the mounts which has fixed the clamping issues. I'll try grinding it again tomorrow if I have time. I have tried the brake with Echo TR clamps and with a TNN booster and also with a Neon booster with LGMS and also Heatsinks with the same effect , which leaves just the rim working up.

Every one seems to have problems with tnn lgms, ment to be the best pads out there... I think they are poor

My LGMs have been the best pads I've used ( HS yellows , Rockpads , Belaeys , CNC HS yellows and "proper" cousts ) and it doesn't take long on the forum to find a topic with Ali C raving about them

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I'll try get some pics up soon , I think the problem is what RobinJI suggested or just it being a bad grind , think it was probably too light or something like that as it is so smooth already . I'v filled the mounts which has fixed the clamping issues. I'll try grinding it again tomorrow if I have time. I have tried the brake with Echo TR clamps and with a TNN booster and also with a Neon booster with LGMS and also Heatsinks with the same effect , which leaves just the rim working up.

My LGMs have been the best pads I've used ( HS yellows , Rockpads , Belaeys , CNC HS yellows and "proper" cousts ) and it doesn't take long on the forum to find a topic with Ali C raving about them

Ali c rides brake less ? What's that got to do with any thing!

What do you wNt from a brake? Noise I'm guessing ?

Personally it's impossible as everyone will be looking for different qualities from abrake

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Ali c rides brake less ? What's that got to do with any thing!

What do you wNt from a brake? Noise I'm guessing ?

Personally it's impossible as everyone will be looking for different qualities from abrake

The Minefield That Are Pads... Help!

He talks the truth here , probably the most accurate thing I have heard about LGMs ,meant to use it as an example

Lots of bite , very strong hold and a decent sound.

Edited by the mysterious leemur
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  • 3 weeks later...

Forgot about this thread , anyway I regrinded the rim and the brake still wasn't quite there and after tinkering about with TNN and Echo TR clamps , with and without boosters (TNN&Neon) I have found that it seems to work best with Echo clamps and Heatsink yellows (plastic backed) for some reason which I'm not to sure of as it shouldn't have been too stiff as it has quite a lot of flex so the TNN set up should have been fine.

Guess it wasn't the right stuff for that particular frame

* My last 20" 4 bolt frame was the Yaabaa 949 though so everything seems flexy next to that , really stiff :giggle: "

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