# Shimano Nexus SG-3C41: can coaster brake be removed?



## anga (Aug 22, 2011)

Hello:

Can the coaster brake attachment (looks like a projecting arm) be removed without any negative effects? If not, can it be left unused?

Best


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## caotropheus (Nov 3, 2008)

You cannot do it. Whenever you back pedal, the hub will also turn backwards and the brake will not work. This "projecting arm" also attaches in a specific place in the hub, so no possibility to assemble it somewhere else.


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## john_dalhart (Nov 6, 2009)

The SG-3C41 (exploded parts diagram) has a roller-cam actuated coaster brake, copied from the old Fichtel&Sachs design. I have never done this with a Shimano hub and IT MIGHT BE DANGEROUS and/or destroy the hub: it might be possible to remove the six rollers from the Y-33R-90700 Carrier Unit and disable the coaster brake, and saw off the coaster brake arm (which, unlike the modern SRAM coaster hubs, is made as an integral part of the Y-35U 98050 Brake Arm Unit).

Me? _I'd sell it and buy an SG-3R40 non-coaster hub_.

jd


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## fokof (Apr 24, 2006)

I have done it on a 7 speed hub by removing the rollers and cuting the arm with a grinder.


You can get some of those hubs dirt cheap, not a big "financial" risk.


I must add : It was not feeling like a normal hub after the transplant , a bit clunky.


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## SPGremlin (Sep 24, 2019)

Yes, it is possible to deactivate the coaster brake on an SG-3C41 so it becomes equivalent to a freewheel hub.

No, just sawing off the external brake arm attachment is not enough (nor is it needed) and can be unsafe.

What is needed is to disassemble the hub from the left side (where the brake arm is) by unscrewing both locknuts and just sliding off the wheel. 

Then remove the "brake pad assembly" part from the hub internals.










After that, one needs to put something elastic around the 6 rollers to push them in and hold them together (like the original brake pad assembly did):

* A keyring of a proper size
or
* A rubber plumbing o-ring like they sell in Home Depot
or
* Perhaps a zip tie (if it is small enough that its head will fit in and won't touch the hub shell










This step is essential to ensure proper gear engagement without extra slack (like a quarter-turn rotation of a chainring until the gear is engaged) after coasting or backpedaling.

That piece does not need to be very strong. Its function is to exert sufficient pressure on the rollers so that it was "easier" for the hub to ratchet (carrier unit against the hub shell) rather than to drag and engage the brake roller clutch while freewheeling or backpedalling. Without this piece, any freewheeling will rotate the roller clutch inside the carrier unit as if the brakes were engaged (though there are no brake pads so no braking will actually occur) - as it is "easier" for the hub internals then proper ratcheting. Then subsequent pedaling will need to undo all that rotation before the gear is engaged, and it results in a very noticeable pedals slack.

After this internal modification, the external brake arm can just be left in place - or sawed-off for cosmetic purposes.

I hope this helps anyone finding this topic in search, even though it took so many years after the original posting.


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## bulletbill88 (Mar 8, 2020)

SPGremlin said:


> I hope this helps anyone finding this topic in search, even though it took so many years after the original posting.


Thank you! This is exactly the advice I was looking for and allowed me to successfully remove the coaster brake from my daughter's Nexus 3 speed hub. She didn't use the coaster brake and the lack of backpedal was hurting her riding as well as getting in the way putting the bike on the car rack and getting the kickstand down.

Easy job to do and the bike rides with no issues.

Much appreciated!


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## SPGremlin (Sep 24, 2019)

Glad that it was helpful! What did you use to push on the rollers - keyring, o-ring, or something else? I did this operation twice, and have a feeling that 3/4” plumbing o-ring is the most robust solution - but i did not take a photo (the only photo I had for this post was with a chainring).

And what bike is your daughter riding?


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## bulletbill88 (Mar 8, 2020)

Agree with the o-ring solution. At first I tried a zip tie but the hub wouldn't fit back together and it didn't feel particularly secure anyway. Two o-rings did the trick, I just grabbed two from a stack of spares I have that gave a snug fit. The hub seems to engage quickly going forward and haven't had any issues.

She has a 20 inch bike (this one: https://www.avantibikes.com/au/bikes/kids-bikes/kids-geared-bikes/spice-20i-kids-bike/) that I have put lighter bmx tyres on, removed the bulky hub shift protector and added pink SDG pedals. I also found a lighter seat post and a set of proper shimano front brakes in my pile of spares. Perfect for a tall five year old.

The priorities for kids bike manufacturers should be 1. make the bike light 2. make it even lighter (hello, your bike weighs half as much as its intended rider!) 3. make it bright colours. Odd how so many don't get this.


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## erebnora (Feb 10, 2021)

SPGremlin said:


> Yes, it is possible to deactivate the coaster brake on an SG-3C41 so it becomes equivalent to a freewheel hub.
> 
> No, just sawing off the external brake arm attachment is not enough (nor is it needed) and can be unsafe.
> 
> ...


backpedal ok but i loose the gears now..


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## erebnora (Feb 10, 2021)

SPGremlin said:


> Yes, it is possible to deactivate the coaster brake on an SG-3C41 so it becomes equivalent to a freewheel hub.
> 
> No, just sawing off the external brake arm attachment is not enough (nor is it needed) and can be unsafe.
> 
> ...


hey hello, i was trying to remove coaster brake and found this page, i did remove the pads as instructed, and yay, it works, i can back pedaling as i want, but as soon as i try to change the gear, the pedals stop moving totally, i had to loose the gear wire then it starts to pedal and backpedal normally. but no gear at all now. does anyone knows what could go wrong?


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## erebnora (Feb 10, 2021)

SPGremlin said:


> Yes, it is possible to deactivate the coaster brake on an SG-3C41 so it becomes equivalent to a freewheel hub.
> 
> No, just sawing off the external brake arm attachment is not enough (nor is it needed) and can be unsafe.
> 
> ...












this is it, its sram imotion 3 gear


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