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PostPosted: Tue Aug 07, 2012 12:45 pm 
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Servicing a MTB for a friend and have come across a problem with the Promax mechanical disc brake fitted to the front of the bike (V-Brake on rear).

I've set it up so the pads (with plenty of life left) are just off the disc however to actually get the brake to work the lever has to be pulled nearly right back to the bars. There is no slack in the cable, as soon as I pull the lever the pads are starting to hit the disc but are not effective until the lever is pulled right back.

The pads are held in place by magnets.

Any ideas? Do you need disc specific levers? As these seem to have too much travel.


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PostPosted: Tue Aug 07, 2012 12:57 pm 
P.o.T.M. Winner / MacRetro Rider
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is there not a rotating adjustment wheel on the caliper?


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PostPosted: Tue Aug 07, 2012 12:57 pm 
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Yes on the inside and outside.


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PostPosted: Tue Aug 07, 2012 1:05 pm 
King of the Skip Monkeys
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see that big silver round bit with the allen key bit? thats your adjustment. From memory, one pad is fixed and that adjustment pushes it towards the disc.

and the red twisty bit adjusts the whole caliper from side to side

Image


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PostPosted: Tue Aug 07, 2012 1:08 pm 
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Yup only there is an adjusting one on the outside too. So I use these adjusting wheels so that the pads are just of the disc but still too much travel on the lever


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PostPosted: Tue Aug 07, 2012 1:11 pm 
King of the Skip Monkeys
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Tel wrote:
Yup only there is an adjusting one on the outside too. So I use these adjusting wheels so that the pads are just of the disc but still too much travel on the lever


its just like adjusting a standard road brake. pull the arm up until the pads are within a 1mm or so of the disc then tighten the cable. any standard v-brake lever is ok.


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PostPosted: Tue Aug 07, 2012 2:46 pm 
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Thats how it is set but still lots of travel. Perhaps I am expecting too much for such lowly components, promax is never going to perform like XTR after all.


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PostPosted: Tue Aug 07, 2012 3:39 pm 
King of the Skip Monkeys
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Tel wrote:
Thats how it is set but still lots of travel. Perhaps I am expecting too much for such lowly components, promax is never going to perform like XTR after all.


it has absolutely nothing to do with 'low end' products. If in doubt, take it to a shop. Promax calipers and their Tectro, Avid and RST cable variants are piss easy to set up and have no issues with 'travel'. You clearly need further assistance - unfortunately its easier to do but an hour to explain.

where the cable connects to the caliper - that lever needs to be pulled up to bring the pads nearer to the disc - then you clamp the cable and use the barrel adjusters to shorten/ lengthen the cable if the pads rub. It never sits at its maximum setting, only like that would you get your problem of 'too much travel' - its like squeezing a set of road brakes nearer the rim before you tighten the cable - same principle.


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PostPosted: Tue Aug 07, 2012 4:25 pm 
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Ooof! Was going to thank you but don't think I'll bother now. Set up plenty of disc brakes before. I do without your advice.


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PostPosted: Tue Aug 07, 2012 4:34 pm 
Gold Trader / PoTM Winner
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.... it IS pretty straightforward to be fair.... but you'll have to just excuse our cheesey friend. He is not unlike a desert cactus. Seemingly prickly on the outside, but inside he's just all wet and soft :lol:



G


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