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In the process of putting a Fantic 305 back together and the discs are knackered. Found someone who will make some for me but they have asked if i want wavy ones or just std discs. 

Question: Ive seen wavy discs on bikes but never knew why. So why would i / should i fit wavy discs and if i do drilled or not ?

Sorry but most of my trials experience has been with drum brakes and i have no idea why you would want to fit wavy discs in fact they look like they would feel really weird in use a bit like having distorted drums but i'm probably dead wrong.

So please enlighten me before i spend my hard earned.

Thanks 

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Round discs,not drilled or wavy.Trials bikes don't go fast enough to benefit from drilled/slotted or wavy discs. Let the pads wipe a flat surface clear and do the braking,anything else will allow mud or stones to be trapped and cause early wear. So pads and discs will wear quicker therefore cost more.To a trials rider this is clearly bad,ALL braking components should last at least 10 years...;)

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First saw wavy discs on mountain bikes. Loads of claims regarding better heat dissipation, better self cleaning. If there is a difference that is noticeable over standard round discs, not just on a theory sheet, it is more likely to be felt on bike subject to prolonged hard breaking. Maybe someone has done a proper side by side comparison 

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If your 305 has two piston calipers and short pads wavy discs might cause pulsing. Drilling is mainly to reduce weight and improve cooling. I would be inclined to go for round discs with a minimal amount of drilling - just enough to help cleaning and improve wet braking.

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Wavy discs are to clean the pad surface, because there is a leading edge to scrape the mud off. Ride through a muddy puddle and a brake with a wavy disc will return its braking efficiency quicker than a plain disc. Plain discs just accumulate a dirty scum on the braking surface. An increase in leading edge area also increases brake performance in the dry, because there will be an increase in bite, something required for low speed trials. Pad life and braking performance are usually inversely proportional, you cant have both.

All of this depends how standard you want to keep the bike looking but IMO a wavy disc will provide better braking.

Edited by faussy
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I can see the logic that a wavy disc will help clear mud etc from the disc/pad surface and can see the logic that it would give a bit more bite to the brake both of which seem to be very desirable for modern trials. They certainly seem to work on my mountain bike. 

 

Old trials fanatic can I ask where your getting the discs from and how much they are charging? I've been looking for some discs for my 309 I've found a couple of companies that make them but no uk resellers for them. 

 

 

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seem to recall 315 mont had a wavy or cast in edge on the rear disc  -  4rt rear disc is more flat finished.

used to find the 315 spare wheel I had gave better braking on the 4rt than the std - especially in the mud  

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5 hours ago, zippy said:

Wavy disc looks cool.

 

I agree to a point but when you have a bike that would have had solid round discs originally I would rather have round discs with slots cut in it than a full wavy disc. I'd most like something like a Beta Evo disc in pattern. 

Edited by smokey125
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On 3/25/2018 at 5:59 PM, smokey125 said:

I agree to a point but when you have a bike that would have had solid round discs originally I would rather have round discs with slots cut in it than a full wavy disc. I'd most like something like a Beta Evo disc in pattern. 

My thoughts exactly

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When they start making brake pads which work on fresh air, I'll start using wavy discs......  

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On my mountain bike the wavy disks get rid of mud / water much better than the solid ones I used to have ... I used to have to pull the calipers off at least every week to clean them (crud in them caused vibration that went through the whole frame and was super noisy), after swapping they've only had to come off once since last october.

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17 hours ago, spen said:

When they start making brake pads which work on fresh air, I'll start using wavy discs......  

Pressure is inversely proportional to area, so via extrapolation a zero disc area (100% air) will have infinite pressure. You could be on to something

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On 28/03/2018 at 4:06 PM, faussy said:

Pressure is inversely proportional to area, so via extrapolation a zero disc area (100% air) will have infinite pressure. You could be on to something

Ah but you haven’t allowed for the earths gravitational pull. Then of course air pressure at sea level is 14.7 psi so the higher in altitude you ride the less infinite pressure you will have! A compressed air cylinder would be needed, thus adding weight back so probably weighing more than the conventional braking system.?‍???

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