Marin B17 98, refurb, and Ebike conversion.

[Soggster]

I have a tired Marin B17 that I've had from new, and an itch for an Ebike, so I thought I'd put the project on here.

My reasons for building an Ebike are nothing to do with disability (I'm slow and fat, but have no other issues ), it's simply because they look like a total hoot! Winter muddy riding may become something to look forward to. So if you are one of the fun police, or think an Ebike is heresy, this may not be the thread for you. If you think they look like fun, or are curious, then join me on the journey. Firstly is to get the bike back up to date and ridable.

So, the forks first.

Marin HI-5 triple clamps weren't great in the day, but with a set of Mountainspeed Speed Springs were pretty capable, and it was a common upgrade. Luckily I had some fitted, so we werent off to a bad start.

IMG-20180821-WA0013 by Andy Stokes, on Flickr

Basically the forks were jammed solid, so it was a bit of a fight to get the legs off. The legs were marked, and the outers were full of water!!!

IMG-20180821-WA0006_resized_1 by Andy Stokes, on Flickr
IMG-20180821-WA0004_resized_1 by Andy Stokes, on Flickr

Plenty of WD40 and a good clean and lube they came out ok.

IMG-20180821-WA0011_resized_1 by Andy Stokes, on Flickr

IMG-20180821-WA0009 by Andy Stokes, on Flickr

Back on the bike and smooth as butter.

Next the Hope C2 brake levers.

These have a rubber bellows type arrangement with a prodder that pushes the master cyclinder. The bellows had perished on both sides

20180824_102949_resized by Andy Stokes, on Flickr

So, after a bit of head scratching of whether to repair or replace I decided to repair.

Onto the PC to create a simplified CAD drawing of the bellows.

20180824_104636_resized by Andy Stokes, on Flickr

Then onto the 3D printer to print them in rubber flex filament. I dont print in flex often, but they came out ok first try.

20180824_111835_resized by Andy Stokes, on Flickr

20180824_111838_resized by Andy Stokes, on Flickr

They fit in the hole. You can see the end of the master cyclinder.

20180824_120614_resized by Andy Stokes, on Flickr

20180824_125531_resized by Andy Stokes, on Flickr
Here's the finished article. Both sides done, and set with the screws. Then I let my nephew out for a ride to test the front shock and brakes. It was a reveltation and like new, so I'm pleased with progress so far. Next up is rear shock and tyres.

 

[coomber]

Re:

Nice labour of love.

Change that bolt there though if you're going into such detail otherwise? Rusty look ruins it.

 

[Timoth27]

Re:

I’d take a dozen of those bellows (subject to price) if you want to make some more

 

[Soggster]

Re:

Hello,

I think I need to make a mk2 version with a little more give. After giving them a good run, they still worked perfectly, but the bellows started to slide in the hole. So either a thinner wall, or a drop of glue. I'll keep you posted.

I have no problem in making a batch when they're perfected.

 

[Timoth27]

Re:

That would be great, do you think you could do the same for the pro lever? As I have a few of both (I might have been a bit over zealous with requesting 12) but I’m sure you could find a few others on here to make it worth doing a good batch.

Thanks

Tim

 

[Madmax1993]

Re:

What sort of ebike kit are you going to use? I do like the idea of turning one of my MTBs into a little hooligan with a BB drive motor, but the ones that look most fun (throttle option and no limit on power) are also really expensive.

 

[Soggster]

Re:

I'm using a Bafang 750w jobby. I've got all the parts, except the battery, so once that arrives I'll post a bit more progress. They do look like fun

 

[Soggster]

So, back from holidays etc, and onto the build.

Next was to replace the terrible standard rear shock. This was probably the weakest link on the whole bike, and it's what was on it from new. I had one replaced under warranty when the bike was less than a year old after it exploded on the Les Gets downhill course. The replacement was also crap.

20180825_121655 by Andy Stokes, on Flickr

So after a bit of a wait on Ebay for one the correct size, 200x57, I got this

20180824_160019 by Andy Stokes, on Flickr

After buying the correct fixings (which I forgot about) I installed it, along with some new Tough Tom Schwalbe tyres because the ones on it were that old the tread was peeling off in lumps.

20180828_191958 by Andy Stokes, on Flickr

The ride is transformed with the rear shock, pedal bob is much reduced, and it's super plush. The forks are now bedded in after a rebuild, and the SpeedSprings are OK, no real adjustment, but they're fairly middle of the road which suits me fine, so all in all very pleased.

Drive train and motor next.

 

[Soggster]

First to change it to a 1x10 with 36 tooth front and 11 to 46 rear.

20180825_102730 by Andy Stokes, on Flickr

Whip out the bottom bracket amd remove the front mech. BB was pretty good nick considering its the original one.

20180925_164939 by Andy Stokes, on Flickr

Then change the rear mech to a long cage 10 speed.

20180926_191943 by Andy Stokes, on Flickr

The standard Bafang front chainring is a 44 tooth big boy, so I changed this for a 36. This bolts to the motor and the whole thing slips though the BB shell and gets nipped up on the other side.

20180925_184053 by Andy Stokes, on Flickr

It has a locking system to stop it slipping about. You need a special tool for this, which doesnt come with the kit, but is on Ebay. Also it only comes with taper cranks, which come in the kit.

20180925_183426 by Andy Stokes, on Flickr

Added on a new set of pedals, and its ready for electricals. Happy with the size of the motor, it's quite small for 750w, and doesn't get in the way. 750w is maximum constant running power, but looking at data readouts in the control box, it's peak power is 1100+ for short bursts.

20180926_191959 by Andy Stokes, on Flickr

 

[Soggster]

I 3D printed a box for the 10ah 48v battery. As the frame isn't an ideal shape I couldn't place it within the frame, so I had to put it low down by the motor, which is quite exposed. The battery didn't have a hard shell, so this was essential.

20180928_091140 by Andy Stokes, on Flickr

The battery box was designed to have the top part the same diameter as the down tube, so with a layer of double sided foam tape, it sits and grips the bike well, and plenty of zip ties to keep it in place. The bottom of the box has notches for the zip ties to grip into.

20180929_101729 by Andy Stokes, on Flickr

The kit comes with sensing barake levers, but not hydraulic ones, so I bought a hydraulic specific pair of sensors. These use magnets and a Hall effect sensor which can tell when the lever moves. They cut the power when the brakes are applied, as you don't want to fight the motor with the brakes. It also has a gear shift sensor which cuts power on shifts to avoid breaking chains etc. This is a test arrangement before the were glued permanently.

20180927_161134 by Andy Stokes, on Flickr

Basically finished and working. The cable managment is a pain, hence the zip ties, but it's all quite neat and tucked away. All the connectors are waterproof, except the main battery one which is an XT90, which is overkill and will be fine. I have put on wider bars, and a slightly shorter stem since these pics, but it's basically the same.

20180929_103202 by Andy Stokes, on Flickr

20180929_103225 by Andy Stokes, on Flickr

Overall the build was simple. I would suggest if you can't make your own, you buy a battery with a hard shell. I have altered the settings in the control unit as it was a little jerky, and this calmed it right down.
Assist has 9 levels of power, and on technical offroad I tend to run at 3 or else it can be a bit mad. At level 9 it's a total rocket, but that's too quick for technical stuff, just for on wide open trails. I'm still dialing it in and getting used to it.

I made it to make winter riding more fun, not as a replacement for my other bikes, and it certainly brings a smile to my face.