iamarapgod

Zip tie the cassette to the spokes. I did this when I first relized I was fix-curious.

shogun17

mmhmm, but locking up the mechanism using a relatively incompressible steel is a little better than zip ties.

Nikola

I was following Sheldon's example: I've made fixed conversion by brazing the cassette freehub body. It's an old Shimano 7 speed. I've took the freehub out, soaked it in degreaser, dried it, and a friend of mine brazed it. I am riding that bike as a commuter/beater since 2013 with no problems at all (unscrewing), even the bearing cup is still OK (I was afraid that during the brazing will loose it's hardness).
Taking apart the freehub mechanism is tricky, requires special tool. simply soaking it in degreaser and then drying is simpler. I think that welding could cause small deformities, brazing will not. That's why I chose brazing over welding.
I recommend you my method, if you want cheap fixed gear conversion. Chainline adjusment is very easy too. I rarely make skid stops, and run a front brake.

Jean Daspry

I want to try and lock up a 3 pawls freewheel, but I don‘t feel confident in my welding skills. Sorry to dig up some 6 years old thread, but I‘m very curious as to what a brazed freehub looks like. Do you have pictures?

I feel like wedging a half grinded old pawl in the front of the freewheel‘s pawl, rather than under it, makes for a safer method, as the wedge will keep jamming the pawl further, the further the freewheel wants to slip.


Btw, nothing is preventing to wedge another one under the pawl, and then even pouring epoxy, but then it‘s much less reversible. I do think using old, recycled pawls, is better than spokes though, as it is of the same hardness.

veganbikes

Just FYI the thread is from 2006 initially and the first response was posted a little more recently but still 6 years ago. Not a great place to ask questions.

In terms of the sucide hubs and welding and gluing stuff like that it isn't a great idea and one no actual real mechanic would suggest. Certainly there are crazy people who would do it and some people may even have some luck but it is not a smart move. If you want a fixed gear get a fixed gear bicycle there are tons and tons of options at varying price points. You can also look at Paul and others who make fixed gear hubs in various widths not just 120. There is also the ability to run a 6 bolt cog on a normal disc hub if you wanted to do that for some reason.

Jean Daspry

Well, there aren‘t a lot of places where people report about their brazed fixed conversion cassette freehub… I stumbled upon this thread by chance so it seems well indexed by search engines, the thread isn‘t closed yet and I‘m staying on topic, is there any major issue?
I think I‘ve already addressed it, but, again, I‘m sorry I have to dig up this thread, and I started by opening a new thread to explain my issue exactly.

I don‘t know what it takes for you to consider someone as an actual real mechanic, but it does seem like welding freehubs is something occasionally done by people having experience working on bikes, some having quite the recognition doing so, like Sheldon Brown.
Not all welds are equal though, and as a definitely not “actual real mechanic”, I don‘t think that is the right solution for me. Hence my interest in “gluing stuff” and jamming pawls.

Thank you for suggesting way better and reasonable ways to obtain a fixed gear for my bike, you are right, unfortunately, my goal to lock my 3 pawls (front) freewheel is not in order to make a fixed gear bike, but to render a mid drive motor compatible with coaster brake. That‘s off topic though, you can go see my thread if you are curious, and/or have suggestions.
I think it‘s better to keep this thread centered on how to convert a cassette hub to a fixed hub.

veganbikes

There is a reason for that most people don't do it and not many threads, that should be a pretty big hint on the idea. Also why you don't see any companies promoting it or building kits anymore to covert (years ago Surly had a fixed freehub but it was a long time ago)

In terms of actual real mechanics, I am talking people who are professional bicycle mechanics. Not just at home hobbyists and people making content, etc...People who actually get paid to repair bicycles either in a shop or mobile outfit or as a race mechanic or in some similar capacity at say Park Tool or Pedro's...

In terms of a mid drive motor and coaster brake those are not a good combo. You want to have good brakes if you are riding an e-bike, they are heavier, and generally faster or maintain a higher speed than your average bicycle and a coaster brake is really a casual brake for a beach cruiser or a required relic of the past for many kids bikes. Flat terrain slow speeds casual riding generally or super crazy cyclists who created mountain biking in the U.S. in the 70s. Plus with a fixed gear, as you are trying to create. and a motor you could easily damage it and burn it out trying to back pedal, the whole reason mid-drive motors disengage as you pedal backwards is so you don't damage them so reintroducing that element is not a great idea.

I am assuming this is a homebrew product because it is unlikely any major e-bike manufacturer is going to have a coaster brake on their bike even the cheapest e-bike cruisers usually have a rim brake at least which is also not super suitable but much better than a coaster brake. I would potentially look at something else that is a good candidate to convert to a electric bike if you really need to do that or get a pre-built e-bike from one of the many established companies using a high quality system like Bosch, Shimano, Brose, Fazua, Mahle...Hydraulic disc brakes are the ideal and are easy to mount on a lot of frames these days and can be had relatively cheaply for a decent set from Shimano or Tektro if you are building from frame up.

Jean Daspry

Yes, very few people need/should have to do that, but that‘s when forums like this one still shine the most, don‘t you think so? Advice about edge cases of bicycle mechanics that you won‘t find ready-made guides for everywhere on the internet, where experienced, knowledgeable and good natured people discuss. That should be a big part of this forum content, am I wrong?

Most of the time, it will be more of a hassle and more expensive long term for somebody to safely convert a cassette hub into a fixed hub, rather than buying a fixed hub. If it‘s not, then it‘s probably not a safe conversion.
But there will always be edge cases, where the alternatives aren‘t really possible/less of a hassle, and that‘s why I do think that discussing of a safe way to do it is worth it.

Freehubs that have the capacity of becoming fixed did exist (SRAM TORPEDO hub), conversion kits (Surly) did exist as you said, and I don‘t see why the “long time ago” should be keeping us from discussing this subject here.

Because my edge case isn‘t really about a cassette freehub or fixed hub, I don‘t think we should be discussing alternatives in this thread. Moreover, even if most of what you said is true, I do think you are missing a lot of the context of my bike and in knowledge of mid motors. I do have a lot to learn too though, so I would be happy to exchange with you in my thread, which is now illustrated with pictures.

JohnDThompson 

+1 this.

veganbikes

Edge cases like that are still the same as you said probably not a safe conversion. The reason why a long time ago is relevant as if it was a great idea people would still be doing it, it would be common and easy to find.

We are exchanging here. The same is the same. I said what needed to be said, I am sure others have said something similar in the other threads. That particular company you have a bike from also makes electric bikes pre-built and ready to go with disc brakes and a Shimano Mid-Drive motor. Would really recommend that.

Jean Daspry

Yeah, I remember the time when children were mainly playing outdoor, or people were buying things to last and did not consider most objects as consumables like in fast fashion or with planned obsolescence, good thing we moved on, right? wait...

I didn‘t want to sidetrack this thread, and I could not imagine you still saying this after having read my thread, but here we are, it seems like moderators don‘t mind us being off topic, and you still clearly maintain your points even after having knowledge of my situation.

I already have and use the bike as is, and it‘s a great familly bike, as it was designed for. I don‘t need a PAS but the wife kinda does, especially after a small leg injury and three growing kids. The front hydraulic brake system is entirely sufficient and the rear coaster brake doesn‘t do too much, but is a very nice redundancy (especially when your hands are already full trying to keep the younger one from throwing stuff out of the bike, or keeping the older one from murdering the first one).

Now I, for one, am always curious to learn new things, so I have quite a few burning questions for you.

Do you think the Christiania Bikes cargo bike, that “actual real mechanics” designed the brake system for (dual front hydraulic disk brakes and rear coaster brake, up to 100kg of cargo, 235kg total), would be significantly affected by the weight of the 10-15 kg of motor and batteries?

Similarly, do you think that the speed while cycling in a flat, urban area, often on pedestrian-shared spaces, with two/three of your hyperactive children in the front and EU legal 25km/h PAS cutoff will be much more challenging than before the conversion, for the “actual real mechanics” designed brakes?


Do you think that the amount of back-pedal rotation required to activate the coaster brake is sufficient to turn and damage the motor, and that the “actual real mechanics” designing coaster brake compatible motors somehow never thought of that?

Don‘t you think that the use of throttle control seems like a more probable “whole reason” to introduce a freewheel between the chainring and the cranks?

Alright, as you might have understood, these are more rhetorical.

Of course, I agree that it would be nicer to be able to put another hydraulic disk brake on the rear, like the “actual real mechanics” of Christiania Bikes did on the new 5,000€ base-price mid drive PAS model.
However, none of what you said seems enough to make it a sine qua non in my case.

Here is a real question, now : Do you really see no way, for under 5,000€, to make my bike safe with a mid drive ebike conversion, other than buying a whole new bike?

I still really appreciate you taking your time to help me.

Jean Daspry

Sorry, I forgot to address your last point :

Where‘s that homebrew product from? Robert Bosch GmbH? Seems to me like a backwater shop with no "actual real mechanics", only "home hobbyists" that don‘t know what they‘re doing.
Same stuff for the guys from Cube Bikes, with their TOWN HYBRID PRO RT 400, or Supreme RT Hybrid EXC 625, both with coaster brakes and Bosch mid drives.

I think it‘s best to keep an open mind and get back to a much more debatable topic, about the ways of locking up a freewheel.

veganbikes

You cannot really sidetrack a long dead thread.

I would say getting a proper bike that is already set up to be an e-bike makes sense on many fronts.

In terms of coaster brakes on Bosch that is something I hadn't seen till recently and still haven't seen on an actual bike from them. But again it is not something I would suggest for a cargo bike.

The first Cube you mentioned has front and rear hydraulic rim brakes from Magura and the second has hydraulic disc brakes front and rear from Shimano so I still haven't seen a bike that is only a coaster brake at the rear and for a cargo bike that I put my kids in, no thank you. People have obviously done it, you have one, but it is usually a situation to save money on their front to hit lower price points. Also in a super flat area like Copenhagen or the Netherlands with a ton of dedicated bike infrastructure and very little distance involved it is a little less of an issue.

The reason I said homebrew because it didn't seem like this was a pre-built product which it is not. If you had a Bosch bike then the question would be different.

Jean Daspry

I was showing you the Cube bikes because it‘s a well known brand even overseas, and that it would maybe make you understand that a mid drive motor can very well be used safely with a coaster brake, without any freewheel between the cranks and the chainring. You seem to have forgotten that just a few days ago you thought that it “could easily damage it and burn it out trying to back pedal”...
Now you backpedal yourself and want me to show you some rear coaster brake only ebike, I will show some to you, but you give me the impression that nothing can really make you change your mind, and that‘s fine, we can just “agree to disagree”.
However you do seem to be very critical of any bike builder putting coaster brake on a bike, which is pretty much every bike builder in Northern Europe, and it doesn‘t seem like you have the technical knowledge or experience to back that up. These bike builders shops have experience building bicycles for hundred of years for some, and they do not compromise on safety. Or in your terms, they are part of the “actual real mechanics” you seem to be speaking for. Maybe your area of expertise isn‘t in utility bikes and that‘s fine too.

Here is a Bosch mid drive with rear only coaster brake, and here is one with a belt drive and Yamaha mid drive. (you can find several dozen of such utility mid drive coaster brake bikes designed by HF christiansen, a more than a century old Danish bike designer)

Ah, so you do realise that the use case of the bike is important when choosing/modifying it! We are making progress.
My Christiania Bikes cargo was also designed (by real actual mechanics) with only rear coaster brakes, and the e-bike conversion, in my (and most of the people with this bike) use case, will not change in a major way the stresses on the brake system.
It‘s very likely that the wife will still be riding slower than me even with the PAS, by the way, but I‘ll be the only one sweating.
If you don‘t want to put your kids in the bike, good news, they won‘t, mine will! Depending on the country you live in, you might want to worry about other things, though.

IAmSam

Considering the lack of traffic here I don't really mind Zombies but I do not get the point of yakking it up about electric mo-peds here either.

Anyway FWIW...getting back on topic almost 2 decades later - here's Fixxer 2.0



https://www.walker-brothers.co.uk/pr...-cassette-hub/

Jean Daspry

Yep, I don‘t get it either... my thread is still here

The Fixxer 2.0 should still be safer that most other solutions to convert cassette hubs, so that‘s great.
The illustration made me realise that there must be very limited options for fixed monocoque wheels, as for changing the hub, well...


vvvvv_____P.S. :





Ok veganbikes, you gave me a good laugh, I‘ll take that as a compensation for wasting my time. I‘ll not answer about that topic anymore here, though all things considered maybe it‘s better you stay in this thread.

veganbikes

But the Cube is not an E-bike with a coaster brake it has hydraulic rim brakes front and rear. So that negates that. Both of the bikes you listed didn't have coaster brakes actually. In the end a coaster brake on a cargo bike is not a great move. I know there are people who use them that doesn't change my mind. Like I said it might be OK-ish in a totally flat area for short rides but again not a great idea for an e-bike. Just because someone does something doesn't make it a great idea. Also a Bosch motor is different from a kit motor but that really doesn't change much.

Also looking at the other bikes you showed they are not big heavy cargo bikes. They do make a e-front loader but it has disc brakes in fact all of their cargo bikes are disc brake equipped. The other bikes are designed for very short very flat rides.

No not worried about that. Children need to know how to use firearms safely and properly and mental health is extremely important as well as better regulation but that is for P&R.In the end though safety on a bicycle is closer to what is being talked about here.