Brake disc wear

[danfoto]

The wife has a 2022 Gazelle ebike with 5-speed Nexus hub and Tektro discs. Because of the steep hills round here and also the way she uses her brakes, I'm thinking ahead to the point at which it becomes obvious that her rear disc in particular is past its best before. So ...

Q1 Is there a generally-accepted minimum thickness for ebike discs?

Q2 Is it feasible to fit a new disc to a Nexus-hub wheel, or will it be a case of a new wheel?

 

[matthewslack]

The wife has a 2022 Gazelle ebike with 5-speed Nexus hub and Tektro discs. Because of the steep hills round here and also the way she uses her brakes, I'm thinking ahead to the point at which it becomes obvious that her rear disc in particular is past its best before. So ...

Q1 Is there a generally-accepted minimum thickness for ebike discs?

Q2 Is it feasible to fit a new disc to a Nexus-hub wheel, or will it be a case of a new wheel?

Have a look at

SHIMANO STEPS E-BIKE Dedicated Mechanical Internal Geared Hub Disc Brake 5-speed | SHIMANO BIKE-EU

As a dedicated E-BIKE hub, the SHIMANO STEPS C7000 series hubs feature a 5-speed range and greater strength and durability for seamless compatibility with mid-ship motors.

bike.shimano.com

and if it is that one, it takes a 'standard for shimano' centre lock brake disc. You need a special tool for the locknut, usually an externally splined one, same I think as the spline pattern on Hollowtech II cranks, but sometimes an internally splined one same as a cassette tool, and it will be quite tight so take care and get help if needed to undo it.

There are many different discs, from about £12 upwards for genuine Shimano. I use only Shimano brake pads on my M200 brakes, B05S being the latest, which are about £9 a pair, and after 4 sets and over 9,000 miles I am considering a disc swap next time the pads need doing. Many Tektros use the same pad shape, and if so I have tried several and none match Shimano for quiet, powerful, fairly cheap, decent lifetime.

 

[Raboa]

From Shimano website

Tune Up Guide - MTB: Disc Brakes | SHIMANO BIKE-US

To Build Closer Relationships between People, Nature, and Bicycles. We believe in the power of cycling to create a better world as we move forward. We inspire all people to enjoy our products in their everyday lives and where they take them.

bike.shimano.com

Braking erodes material off the rotor depending on the riding conditions, rotors will typically last through two or more sets of brake pads. When a SHIMANO rotor measures 1.5mm thick or less, it's time to replace it. A new rotor should always be accompanied by new brake pads.

Diisk rotors are either 6 bolt or centrelock fitting, if using 6 bolt tighten the bolts in a star shape pattern, this stops putting excess pressure on one side of the disk. I also give the bolts a clean with isopropyl alcohol, and apply fresh threadlock. Some people use a torque wrench, if doing this tighten each bolt half the recommended torque setting then tighten full torque setting.

Torque Specifications | BikeRide

www.bikeride.com

 

[AndyBike]

Some people use a torque wrench,

Its a good idea to have and use a torque wrench, and they arent too expensive.

Thing is many people are heavy handed and if you overtighten you can crack the hub mount, which then means you shell out a lot of money for a simple and silly mistake.
If you undertighten, theres a chance the bolts can vibrate loose, and once they stick out too far they'll rip the hell out of whatever they come into contact with like the caliper itself or the frame, or in the case of rotors rip the darn thing off the hub when you apply heavy braking.

And all for the want of a £30 tool.

 

[danfoto]

Thanks folks

The hub is actually a Shimano Inter-5E and now I've been able to look closer, the Tektro disc is held onto the "spider" with what appear to be countersunk machine screws. Not sure what the correct term is for the type, but instead of having a normal Allan-screw hex socket they'll need a star-shaped bit to shift 'em. So it looks like the discs themselves are a doddle to change.

Although the discs are Tektro, Shimano's 1.5mm minimum's good enough for me. We do use Shimano pads, btw - just got a batch of BO3S from Rutland Cycling at a good price which will keep us going for a few years ...

 

[Raboa]

It is a T25 torx bit you need for the bolts, buy a good quality bit, I like Wera stuff

 

[danfoto]

Ta for that

 

[AndyBike]

Ta for that

Jobsworth Bicycle Repair Workstand | Planet X Bikes

JOBSWORTH BICYCLE REPAIR WORKSTAND. Super stable, height adjustable and featuring a built-in tool tray. Durable steel construction Folds easily for storage Includes adjustable tool tray. Durablable steel construction Folds easily for storage Includes adjustable tool tray Rubberised rotating...

www.planetx.co.uk

 

[nigelbb]

Its a good idea to have and use a torque wrench, and they arent too expensive.
<snip>
And all for the want of a £30 tool.

When I collected my Wisper 705 the original owner used a little torque wrench set when he dismantled the bike enough to get it onto the rear seat of my Jaguar S-type. I was so impressed that I ordered the same torque wrench set from Wiggle the next day.

LifeLine Essential Torque Wrench Set | Wiggle

Buy your LifeLine Essential Torque Wrench Set from our Wrenches range at Wiggle. £39.99. Free delivery available.

www.wiggle.co.uk

 

[danfoto]

Why on earth would anyone use a torque wrench to unscrew fasteners?