Shimano Wandering Bite Point Fix? Vital MTB Gear Show 14

Mountain bike news and reviews, hot off the press!

iceman2058
12/1/2022 11:58pm
GEARSHOWA

Is there a mineral oil that can help with the inconsistent bite point found on some Shimano brakes? The answer to this question and tons of other news and reviews in this episode of your favorite gear show!

 

Time stamps:

0:00 Intro
0:33 A Month in a Minute (industry news round up)
2:48 Delium Versatile review
5:30 Bleedkit.com review
7:45 EVOC Hip Pack Pro 3 review
9:50 Wolf Tooth Waveform pedal and Echo grip review
12:30 PNW Components Loam Lever Gen 2 review

Links:

Yeti SB120
Yeti SB140
Yeti SB160
Mondraker 2023 range
2023 Marin Rift Zone
2023 Scott Genius
New Transition TR 11
Redesigned Orbea Wild
Propain US Showroom opening
We Are One Composites launches Convergence rim
Orbea introduces wheel brand Oquo
First Fizik shoe with Gore-Tex
RideWrap launches Tailored Protection program
New Protaper Alloy and Carbon handlebars
Three new Nukeproof components
Race Face introduces the Era carbon crank
ABUS introduces the Cliffhanger helmet
Endura launches the MT500 helmet
Leatt 2023 range of protection and apparel
Magura Vyron MDS-V3

Review section:

Delium Versatile tire
Bleedkit.com
EVOC hip packs
Wolf Tooth Waveform pedals
Wolf Tooth Echo lock-on grips
Updated PNW Components Loam Lever

 

Related:
Vital Gear Show
Hydraulic Disc Brakes
Brake Accessories
Shimano
SRAM
Bleedkit.com
Evoc
Hydration Packs
Flat Pedals
Grips
Wolf Tooth
PNW Components
Tires
Delium
Yeti
Mondraker
Marin
Scott
Transition
Propain
Orbea
We Are One Composites
Fizik
RideWrap
ProTaper
Nukeproof
Race Face
ABUS
Endura
Leatt
Magura
14 comments

View replies to: Shimano Wandering Bite Point Fix? Vital MTB Gear Show

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noideamtber
2 years ago

When bleeding Shimano brakes, Pressurize the system, My friend made some Bolts that work similar to sram's BLeeding edge for the shimano levers/calipers.

Bite issues gone and it smoothed out the lever, Now not requiring huge lever power to get any real power after that famous off/on "hit"

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HexonJuan
2 years ago

Re: The wandering bite point, I got curious as I had two SLX units develop it after a bit over 2 years of use. Warranties be damned. I installed a set of aftermarket phenolic caliper pistons and the problem went away at a slight cost. The AM units slip more than the ceramic ones, so the pad gap is reduced, but if you've set up a Formula brake it's much the same. From what I could figure looking at the pistons under 15x, the ceramic pistons have a rougher surface finish which held a lot of debris in the pores, likely a combo of brake dust, dirt, and possibly rubber from the square seals in the caliper, which in turn likely prevents the piston from slipping past the seal properly. This would also explain why I've yet to come across the issue on non series Shimano brakes using phenolic caliper pistons. They worked until the MC pistons gave out, one locking in the bore and the other developing a hole in the primary cup seal. Both were measured and found larger in diameter than the ones that were still functioning. Hunch is the plastic fatigued and began expanding during use, like when you step on an aluminum can it bulges prior to collapsing. Of note, I only ever used Shimano fluid in the brakes, so it shouldn't be occurring due to fluid contamination. The last bit, I took one of the MC bodies to the band saw to see how the ports were laid out. Surprising to me and my buddy who's a moto mech, there wasn't a compensator port hole in the body. That explained why near every single Shimano brake I've bled new on bike or from a box has had air in the MC. The space between the primary and secondary seal is likely holding air at initial assembly and only escapes to the res during use. All in all, I loved the brakes until they started crapping out. With factory parts being non-existent and support questionable post warranty period, I opted for another brand that uses phenolic caliper pistons and alloy MC pistons and has spares available.

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HexonJuan
2 years ago

On what basis? Not trying to be an argumentative grouch, but i'd like to read what drives that thought. It was the only thing the remedied the issue once it crept up for me and was based on observation on other products from the same co, in same vintage. Granted, I didn't try other fluids, but for a problem to arise over time rather than outta the gate points to a non-fluid related issue. Regardless, I've changed brake brands and have been fine so far.

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Jakub_G
2 years ago

Shimano brakes are known to have multiple issues that can manifest in more than one way, lever throw change is just the most obvious one. Yes surface roughness you mentioned is one of them and I guess it's designed that way for pad rollback reason(Shimano has most likely the highest number there, and is likely reason for pad contamination that seems to happen overnight when the bike is not used at all for prolonged time), which leads to likely issue no 2., not big enough port size in the lever, which leads to insufficient oil flow when pumping the brake. If you change oil to something with lower viscosity (putoline is the most prevalent fix), it helps to fix this issue, at least for most people. Third thing is lack of anodising of the MC bore that leads to dirty oil after relatively short period of time with aluminium particles contaminating it and causing wear everywhere. Shimano brakes are pretty good design wise, just let down by low quality parts/low tolerances to keep the price in check.

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KAO80401
2 years ago

proper for me to chime in on bite point consistency. i've used a lot of different alternatives to shimano mineral oil including the mineral oil touted in this review. this is good mineral oil but does not "fix" bite point issue. you may be able to go much longer on steep, long tracks without vaporizing oil but the bite point issue can still arise. i've used this oil and bunnyhop tribe oil which I believe is the same. there's actually a moto bath oil that i've found to be the best nevermind your official shimano warranty...

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iceman2058
2 years ago

As documented in this video, we tested the oil back to back with the original, and we absolutely did find an improvement in bite point consistency. We're not saying this is the only oil which does this, but we are saying that it does. To be clear, the wandering bite point has nothing to do with air in the lines or with the oil heating up on longer descents. I think it has something to do with how fast the system is able to reset after each pump of the brake, which is why these "highly fluid" oils work better - they allow for faster movement of oil between master cylinder and hose, back and forth. I also believe the ServoWave lever accentuates any problem, since it delivers a very high initial leverage ratio which means that it will amplify any inconsistencies felt at the finger level during the first part of the stroke. The bite point issue does not affect the power of the brake, once the timing port of the master cylinder is closed, you get the same leverage from the lever to the caliper pistons. The issue arises because an inconsistent amount of oil is present in the closed part of the system once the master cylinder piston moves past the timing port.

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