Sketchy brakes

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ChrisS
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Sketchy brakes

Post by ChrisS » Sat Apr 24, 2021 4:44 pm

I've been updating various bits on my hardtail ahead of the Highland Trail group start in May. It's just got a new chain, cassette and shifter and I've got new tyres to put on in a couple of weeks. BB and mech are fairly new anyhow and the bike's just had a full service and a clean bill of health.

The only bit that's bothering me are the brakes. They're pretty low spec (Shimano M315) and can feel quite sketchy when riding a loaded bike down steep, loose stuff. I use B01S pads and have a new set to put on a couple of weeks before the start.

I'd wanted to replace the brakes with something a bit better before the race, but the bike upgrade cash pot is running a bit dry :lol:

All the other kit on the bike is XT, I was looking at SLX brakes but can't stretch to those now. Any other options or tips (different pads) that might improve the braking without a massive outlay?

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Bearbonesnorm
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Re: Sketchy brakes

Post by Bearbonesnorm » Sat Apr 24, 2021 5:27 pm

What size rotors have you got fitted?
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ChrisS
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Re: Sketchy brakes

Post by ChrisS » Sat Apr 24, 2021 6:02 pm

Bearbonesnorm wrote:
Sat Apr 24, 2021 5:27 pm
What size rotors have you got fitted?
160mm rear, 180mm front.

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sean_iow
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Re: Sketchy brakes

Post by sean_iow » Sat Apr 24, 2021 6:08 pm

Don't forget that if it's wet you'll want to carry 2 spare sets (4 pairs of pads) so if you buy new brakes you'll need to factor that into the cost.

I had 180mm front and rear when I did it.
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ChrisS
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Re: Sketchy brakes

Post by ChrisS » Sat Apr 24, 2021 6:34 pm

sean_iow wrote:
Sat Apr 24, 2021 6:08 pm
Don't forget that if it's wet you'll want to carry 2 spare sets (4 pairs of pads) so if you buy new brakes you'll need to factor that into the cost.
As I’ve been finding out, this ultra racing lark is an expensive business!

I bet your spare pads were all broken in just right too :ugeek:

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sean_iow
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Re: Sketchy brakes

Post by sean_iow » Sat Apr 24, 2021 6:45 pm

I had tried them all in the calipers. The HT550 is not the place to find out they were made wrong or in the wrong packet and don't fit.

Look on the bright side, I've got Hope brakes, so new pads+ 2 spare sets cost £120 :o
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Bearbonesnorm
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Re: Sketchy brakes

Post by Bearbonesnorm » Sat Apr 24, 2021 7:04 pm

160mm rear, 180mm front.
I was hoping you were going to say 160mm front and back. Could be the dreaded Shimano micro-leak ... are the noisy at all?
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Re: Sketchy brakes

Post by Lazarus » Sat Apr 24, 2021 7:32 pm

new pads+ 2 spare sets cost £120
Superstar or uber bikes pads will cut that BY 66% ish

Never had a problem with either [also using Hope brakes]

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htrider
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Re: Sketchy brakes

Post by htrider » Sat Apr 24, 2021 8:14 pm

Pretty sure all Shimano brakes are the same power wise the difference being weight and adjustability. Certainly the deore ones on the fatbike are the same as the SLX ones on the Jones. Hope do 220 disks these days!
Re spares for the HT, in 2015 (wet) I burned out both front and rear shimano sintered metal pads by the end. One spare set if its dry 2 if its wet.

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Re: Sketchy brakes

Post by Cyclepeasant » Sat Apr 24, 2021 9:02 pm

:o
Wow!
I have never burnt out a set of pads in any event including 8,12 and 24hr events in all sorts of weather conditions.

Be interesting to know how to achieve it! (Curious)

And how many of you do!
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sean_iow
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Re: Sketchy brakes

Post by sean_iow » Sat Apr 24, 2021 9:11 pm

I think it's the quartz dust in the mud? It also wears away your shorts and saddle. Everything has a glint in the sun afterwards as it's everywhere.
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htrider
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Re: Sketchy brakes

Post by htrider » Sat Apr 24, 2021 9:19 pm

Cyclepeasant wrote:
Sat Apr 24, 2021 9:02 pm
:o
Wow!
I have never burnt out a set of pads in any event including 8,12 and 24hr events in all sorts of weather conditions.

Be interesting to know how to achieve it! (Curious)

And how many of you do!
Aye twas a shocker as new sintered pads typically last for yonks. As Sean says, up north the mud is a mix of mud and granite dust which is like grinding paste. Friends who live up there have written off frames as the seat tube has worn so thin with putting the seat up and down (pre dropper) they have cracked. Interestingly in 2017 which was fairly dry, my pads were less than half worn by the end. Several people scratched in 2015 just because they ran out of brake pad.....

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Re: Sketchy brakes

Post by Cyclepeasant » Sat Apr 24, 2021 9:35 pm

Interesting.....worn seat tubes!

Does it result in worn discs also?

:???:
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ScotRoutes
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Re: Sketchy brakes

Post by ScotRoutes » Sat Apr 24, 2021 9:37 pm

When I lived in Edinburgh, I didn't know that jockey wheels ever wore out.

Here in Aviemore, they're a consumable. :lol:

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Jurassic
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Re: Sketchy brakes

Post by Jurassic » Sat Apr 24, 2021 9:49 pm

I had those brakes on my bikepacking bike and demoted them to a spare loaner fat bike I built up for fatty curious friends to borrow (I put XTs on my bikepacking bike). On the loaner fatty I used 200/180 rotors (despite Shimano saying it shouldn't be done) and it increased the power a fair bit. Just for transparency, the loaner fatty hasn't done many miles so I couldn't vouch for long term reliability. I've also found that the B01S pads wear out pretty quickly compared to sintered pads so I think taking a few spare sets would definitely be a good idea.

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ChrisS
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Re: Sketchy brakes

Post by ChrisS » Sun Apr 25, 2021 8:54 am

sean_iow wrote:
Sat Apr 24, 2021 6:45 pm
I had tried them all in the calipers. The HT550 is not the place to find out they were made wrong or in the wrong packet and don't fit.

Look on the bright side, I've got Hope brakes, so new pads+ 2 spare sets cost £120 :o
Ouch!

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ChrisS
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Re: Sketchy brakes

Post by ChrisS » Sun Apr 25, 2021 8:55 am

Bearbonesnorm wrote:
Sat Apr 24, 2021 7:04 pm
160mm rear, 180mm front.
I was hoping you were going to say 160mm front and back. Could be the dreaded Shimano micro-leak ... are the noisy at all?
Generally pretty quiet unless it's wet.

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Re: Sketchy brakes

Post by jameso » Sun Apr 25, 2021 8:55 am

ChrisS wrote:
Sat Apr 24, 2021 6:02 pm
160mm rear, 180mm front.
I don't think 180mm rears are OTT on loaded bikes. Weight gain isn't worth considering, braking gain or reduced heat build up on long descents is, seems like a 'why wouldn't you?' upgrade to me.
Those Shimano brakes probably come with rotors that aren't rated for metal sintered pads but for one event I'm not sure if it'd be a problem - I doubt it, esp if using larger rotors and not being heavily loaded or a heavy rider.

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Bearbonesnorm
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Re: Sketchy brakes

Post by Bearbonesnorm » Sun Apr 25, 2021 10:20 am

I don't think 180mm rears are OTT on loaded bikes
I agree they're not overkill but a brake is only as good as the level of grip available. Given the weight transfer under braking and the reduced rear grip, I tend to think larger rear rotors are of limited benefit. :wink:
Generally pretty quiet unless it's wet.
Micro leaks at the caliper tend to make them squeal, so perhaps not that.
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ChrisS
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Re: Sketchy brakes

Post by ChrisS » Sun Apr 25, 2021 12:16 pm

jameso wrote:
Sun Apr 25, 2021 8:55 am
ChrisS wrote:
Sat Apr 24, 2021 6:02 pm
160mm rear, 180mm front.
I don't think 180mm rears are OTT on loaded bikes. Weight gain isn't worth considering, braking gain or reduced heat build up on long descents is, seems like a 'why wouldn't you?' upgrade to me.
Those Shimano brakes probably come with rotors that aren't rated for metal sintered pads but for one event I'm not sure if it'd be a problem - I doubt it, esp if using larger rotors and not being heavily loaded or a heavy rider.
Have to admit it hadn't thought about changing the rotors. I'm not sure even how long they last. The current set have got about 9,000km on them with lots of hills.

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Re: Sketchy brakes

Post by jameso » Sun Apr 25, 2021 1:00 pm

I agree they're not overkill but a brake is only as good as the level of grip available. Given the weight transfer under braking and the reduced rear grip, I tend to think larger rear rotors are of limited benefit. :wink:
In a harder braking or short stop situ there's less than the benefit of the front, though on longer descents I find a bigger rear can mean less pressure on the front brake plus the larger rear does cope with heat better when you're trying to keep a heavier bike under control. Even just being able to control the bike more from the back brake with less effort at the lever is good.
One thing I know is that having a truss fork, good tyres and 180mm brakes on a bike where it's really easy to get your weight well back, is the people riding with you learn to leave some braking distance when they're behind : )

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Re: Sketchy brakes

Post by BigdummySteve » Sun Apr 25, 2021 9:21 pm

As a 100Kg lump I’ve had my fair share of brake issues with my Fargo. I’ve tried many disks, 200 mm front disks do increase stopping power but I just didn’t like the feeling. Possibly the best rotors I’ve used are shimano icetech, quite like my current hope floating jobs but the feeling isn’t as nice as the icetech ones.
Bleed them to death! Using some really good syringes, the Avid professional kit is good, de-gas the fluid using negative pressure (not sure if this applies to oil) either remove the caliper or put the bike in a stand so can you spin it vertical, pump the pistons out then push them back in with the port open, air often hides at the back of them, yes this means all pistons separately. I have a block cut to hold all pistons apart from one which I made up. While you’re doing this tap the hoses and calipers to dislodge air while applying negative pressure to expand any bubbles.
A good bleed is the key starting point, getting some decent tools made a huge difference.

Apart from bleeding I also regularly pump the pistons out a little, clean them and lube the seals.
Also check pad alignment and centring.

My drop bar brake woes eventually led me to hope RX4 calipers with 180mm rotors paired with Kevlar pads, no issues for two years now. Being a fat bugger definitely highlights any problems :lol:
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