1st build / and 1st post / Grin build

Ahoy, I've been reading here for about a year... thanks to all of you who've posted so much info to make this build easier. Most of what I'm doing is a result of ideas I got from you folks. Posting this build to pitch in to all the info and, of course, to receive suggestions.

I have an old bike that I built about 20 years ago and since have given it away 3 times and it keeps getting returned to me every few years. I got it back again a couple months ago and I think it is a prime candidate for an E build.

It's a 26" Santacruz Heckler from about 1998. Full suspension, which is quite nice. It's a little small for me but for easy cruising with the seat low it is pretty comfortable. For technical riding (high seat) that requires a lot of pedal torque it's not the most comfortable... but having Epower should fix that. Otherwise it checks a lot of boxes for a nice build.



The bike was originally assembled with really nice and interesting components, mostly Shimano XTR, that all still work. I'd have liked to have larger wheels but that's not going to happen with this bike so I'm going to just lean into the smaller wheels and even go so far as to make the rear a 24". So 26"/24" mullet. 24" wheel will be a little stronger, I might get a little better torque with the 24", and with the 26" wheel on the rear, I can't put a fatter tire on the rear because the seat stays are too close together, so with the 24" wheel on the rear I can put a fatter tire between the seat stays. 24"x2.3 Maxxis Minion DHR II. It already has a 26" Maxxis Holyroller on the front. This bike was built when a 2.1" tire was considered fat on an mtb.

So prepping the bike... So far I upgraded the front brake from a 160mm rotor to 180mm. I added a PNW dropper post yesterday... I can't live without a dropper anymore on any bike. And I've rerouted a couple cables to stay out of the way of the battery. I'm going to have to fab up a custom battery tray.

The parts. Grintech GMAC8T, Phaserunner, and Cycleanalyst, Erider torque sensing bottom bracket, and Luna has the 52v14ah Battery I want. I haven't ordered any of it yet. Waiting on some email responses and the battery is out of stock right now.

In list format...

Grintech:
GMAC8T
Phaserunner
Cycleanalyst
Erider torque sensing bottom bracket/165mm crank arms. It has 180mm crank arms on it now... way too long for a cramped cockpit.

Luna:
52v14ah battery

A couple things that I think will make this build fun and unique...

1. It's full suspension!!! Before I got this bike back, I had a really hard time identifying a full suspension frame that would work. Very hard to find. And bam... this bike comes back to me, FOR FREE, still in good shape and the front triangle will accommodate hardware.

2. This bike never had a dropper before mostly because it's a 27.2 seat post. But now a couple companies have 27.2 droppers. I chose the PNW Pine 27.2. It's nice. And to top it off, I'm going to run the drive train as a 1x9 so I can use the left shifter to actuate the dropper eliminating one more thing off the bars. A full suspension Ebike with a dropper... nice.

3. Hopefully the pics will post... because it has these really cool old XTR shifters that have a multifunction brake lever that moves in three directions so can pull back for the brake, of course, and push down or up to shift. one lever!... so nice. anyway, the left one will actuate the seat post. The right shifter will remain on the rear derailleur. This means I'll only have 4 things on the handle bars... Left shifter that is a brake and seat post combo, power/multifunction button next to the left brake/seatpost lever, cycleanalyst in the middle, and the right shifter/brake combo at the other end. Not sure If I'm going to add a throttle. I think I'd like the bike to be class 1. With no throttle, that's everything on the handlebars in 4 mounting points. 5 points if I add a throttle.




4. The 26/24" mullet and a soft suspension set up will slack the bike out a bit. It's an older XC bike with a steep rake. You're really right over the handlebars with the seat up on this thing. Add the dropper and I think slacking the rear will make it more comfortable for the riding I have in mind. Basically, I want it to feel more like a beach cruiser bike like you'd ride on the boardwalk... sitting more upright and easy pedaling... but with mtb goodies... like suspension.

I'm trying to get the bike "ready" to buy the Grin/Luna stuff. Still waiting on a couple cables for the rear derailleur and seat post... I used old cable housings to mock up the cable arrangement. Also waiting on the rear 6 bolt 160mm rotor, the one on the bike is a centerlock. 24" Maxxis Minion. And also waiting on email responses for a couple questions I had for compatibility. I'm 95% sure the parts list is all compatible.

So....... looking forward to this thing. I've been wanting an Ebike for a long time. All the ones I like are crazy expensive. I think I can pull off this build for less than half of the cheapest manufactured Ebikes that I've been interested in.

I'm way open to ideas if anyone sees any issues with this build. The theme is easy smooooove cruising with the seat low (most of the time) and the suspension set up soft. No big rocky technical trails... I'd use my analog bike for that.

...okay. i was able to add links to pics but not the actual pic? can anyone see my pics in the above post?

Since you're going with a 24" rear, what's your plan for rear brakes? If you're using regen with the GMAC, you won't need the rear brake lever. Might be cool to convert that into a variable regen lever. :thumb:

Also, depending on the frame size, be careful about measuring for your battery, since the swingarm pivots in to the triangle. I thought about converting my Tazmon, so I'm interested in seeing how your bike turns out.

E-HP said:

Since you're going with a 24" rear, what's your plan for rear brakes? If you're using regen with the GMAC, you won't need the rear brake lever. Might be cool to convert that into a variable regen lever. :thumb:

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It'll be a 160mm disk on the rear to start. The GMAC has the 6 bolt disk option. I do believe you can do a sort of reverse throttle thing for the regen... I have considered something along the lines of what you're suggesting. A button brake might be cool even with the disk. I just haven't gone down that discussion line with grintech. I'm trying to not wear out my welcome with a ton of questions. But I think it's already been done.

I have measured for the swing arm... thanks though! That's exactly the foresight I'm hoping for from the forum.

JeffnAZ said:

...okay. i was able to add links to pics but not the actual pic? can anyone see my pics in the above post?

Click to expand...

Nope. But there's a sticky up top that tells you how to post pics. Works best to upload to the forum server, after reducing the size to fit within the limit.

JeffnAZ said:

It'll be a 160mm disk on the rear to start. The GMAC has the 6 bolt disk option. I do believe you can do a sort of reverse throttle thing for the region... I have considered something along the lines of what you're suggesting. A button brake might be cool even with the disk. I just haven't gone down that discussion line with grintech. I'm trying to not wear out my welcome with a ton of questions. But I think it's already been done.

Click to expand...

You mentioned 98, so I assumed no disc mounts since Santa Cruz didn't add them until 2000

E-HP said:

JeffnAZ said:

...okay. i was able to add links to pics but not the actual pic? can anyone see my pics in the above post?

Click to expand...

Nope. But there's a sticky up top that tells you how to post pics. Works best to upload to the forum server, after reducing the size to fit within the limit.

Click to expand...

...still working on it from the google end... i'll look at the sticky now. haven't been on any forums in years. I used to the the guy with the answers.

E-HP said:

JeffnAZ said:

It'll be a 160mm disk on the rear to start. The GMAC has the 6 bolt disk option. I do believe you can do a sort of reverse throttle thing for the region... I have considered something along the lines of what you're suggesting. A button brake might be cool even with the disk. I just haven't gone down that discussion line with grintech. I'm trying to not wear out my welcome with a ton of questions. But I think it's already been done.

Click to expand...

You mentioned 98, so I assumed no disc mounts since Santa Cruz didn't add them until 2000

Click to expand...

I could be a year or or so off on the year the bike was built. It has disks on it now. ...and unused post mounts as well.

JeffnAZ said:

...still working on it from the google end... i'll look at the sticky now. haven't been on any forums in years. I used to the the guy with the answers.

Click to expand...

The biggest difference I see on forums is the preference to upload photos rather than links or hyperlinks. That's because the whole Photobucket hostage situation was a big lesson learned where all the photos in older posts disappeared, not only here, but virtually all forums. Forum itself seems to be the same semi-dysfunctional family of very knowledgeable folks trying to get along. :lol:

Welcome to the forum, by the way.

E-HP said:

Welcome to the forum, by the way.

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Thanks!

E-HP said:

The biggest difference I see on forums is the preference to upload photos rather than links or hyperlinks. That's because the whole Photobucket hostage situation was a big lesson learned where all the photos in older posts disappeared, not only here, but virtually all forums. Forum itself seems to be the same semi-dysfunctional family of very knowledgeable folks trying to get along. :lol:

Click to expand...

got it! my pics were way too big.

No E updates yet but ... She's a roller!!!

Converted the front tire to tubeless. Neither the rim nor tire are TR but I got it sealed and it's holding.
Cut down the seat post about 5/8" (~16mm).
Swapped on a better seat, more comfortable, and with a lower stack height and wider butt coupling. So the seat is a total of about 1.5" lower (~35mm). It feels pretty comfortable with the dropper post at any height. I'm really happy with that result. I was tempted to go lower but I couldn't bring myself to drill a hole in the flag (pic below). And it came out perfect anyway.
Played with the suspension settings.
Cabled up the rear derailleur and seat post.
Bled the brakes. They were both low on fluid. The 180mm front rotor upgrade did not provide the stopping power I was hoping for. Not sure why but it'll be good for now. I pulled the pads, which I think are approaching 20 years old, and they looked normal. I put the thickest two pads in the front and there was no change... pads are cheap.

Took her out for a ride and I really like this bike! It's a legit mountain bike! It rolls so smoooooth and it feels fast and the suspension is pretty plush considering the age of all of it. Can't wait to get some Epower on this thing. And I think the 24" wheel laced up to the GMAC slacking it out just a bit more is gonna be perfect.

Hope everyone had a great weekend, J

Still not an E update... But more "readying" the bike today.

One of the goals with this build is to hand it off to my grandson as soon as he is big enough to ride it, and he's getting close already, so I'm making the cockpit small guy ready.. and I kinda wanted an excuse to try narrow bars. So I cut 'em down today. Got 'em down to 735MM from 780MM. I gotta say, I've been riding +770mm bars for so long I forgot this nice snug&tucked feeling of narrower bars. This bike is really nimble. It'll be interesting to see if it maintains that feeling with ~10lbs added in the front triangle.

...also threw on some new grips that've been floating around in my bike parts bin for years.

Anywho... parts are on the way. slooooowly.

With some effort, I would suggest using Bafang FAT motor machined to fit 135mm dropout like I did.
You will save money on motor purchase and gain a way more torque with slight motor weight increase compered to GMAC.
My modified Bafang FAT running at 78V battery is holding 3,5KW peaks no problem. Top speed 62 km/h with 26 wheel.

As well, use higher voltage if possible. P(W)=U(V)*I(A), by increasing the voltage amps can be decreased maintaining the same power. Amps=heat.

Universalus said:

With some effort, I would suggest using Bafang FAT motor machined to fit 135mm dropout like I did.

Click to expand...

You gave up your bike's gears and got a bad chainline that way. I don't think that would suit most people.

Chainline isn't perfect, it is like using a cassette on the second smallest ring. However, my bike has 3 chain rings at the crank. so basically 3 gears available. Usually all the time I use the biggest 44 T at the front.
The only one downside of using single speed cassette is that they are relatively large: 18T or bigger.

Universalus said:

The only one downside of using single speed cassette is that they are relatively large: 18T or bigger.

Click to expand...

16t is the smallest and most common size of freewheel for 1.37" threads. 16, 17, 18, 19, 20, and 22t are all easy sizes to get. 15t was made in the past, but not recently.

You are right, thanks

Universalus said:

With some effort, I would suggest using Bafang FAT motor machined to fit 135mm dropout like I did.
You will save money on motor purchase and gain a way more torque with slight motor weight increase compered to GMAC.
My modified Bafang FAT running at 78V battery is holding 3,5KW peaks no problem. Top speed 62 km/h with 26 wheel.

As well, use higher voltage if possible. P(W)=U(V)*I(A), by increasing the voltage amps can be decreased maintaining the same power. Amps=heat.

Click to expand...

I appreciate the input... I wanted to keep the rear cassette capability and I'm not building a torque/speed beast. It's intended to be an easy cruiser with a decent range. I'm planning a 52V batt if I can cram it in the triangle. But I think I can go as low as 36V and make the bike what I want it to be. The only ones I can find that check all the boxes are out of stock.

Still waiting for parts... but here she sits ready to be fun.

I did get a good deal on a used replacement shock. The original was old, leaky and noisy. So old that I couldn't find a rebuild kit and it looked pretty worn inside the air can. So a rebuilt replacement ended up being cheaper than a rebuild from any company willing to even look at the old one.

Universalus said:

With some effort, I would suggest using Bafang FAT motor machined to fit 135mm dropout like I did.
You will save money on motor purchase and gain a way more torque with slight motor weight increase compered to GMAC.
My modified Bafang FAT running at 78V battery is holding 3,5KW peaks no problem. Top speed 62 km/h with 26 wheel.

As well, use higher voltage if possible. P(W)=U(V)*I(A), by increasing the voltage amps can be decreased maintaining the same power. Amps=heat.

Click to expand...

Sorry to go off topic of this interesting thread but what machining was required? Is it just a matter of shortening the freewheel side axle and grinding the axle flat to fit the dropout? Bafang has a 1000w geared hub but only available for 175mm dropout

Universalus said:

With some effort, I would suggest using Bafang FAT motor machined to fit 135mm dropout like I did.
You will save money on motor purchase and gain a way more torque with slight motor weight increase compered to GMAC.
My modified Bafang FAT running at 78V battery is holding 3,5KW peaks no problem. Top speed 62 km/h with 26 wheel.

As well, use higher voltage if possible. P(W)=U(V)*I(A), by increasing the voltage amps can be decreased maintaining the same power. Amps=heat.

Click to expand...

That's pretty amazing for a geared hub. I'd love to see the bike in action.

I would bet that motor is very efficient due to the square-ish shape of the stator.. and that's why it make that insane power.

electric_nz said:

Sorry to go off topic of this interesting thread but what machining was required? Is it just a matter of shortening the freewheel side axle and grinding the axle flat to fit the dropout? Bafang has a 1000w geared hub but only available for 175mm dropout

Click to expand...

Not only does the freewheel site axle have to be thread cut and ground to fit the dropout, but the disk brake site as well. Disk brake mount on the rotor has to be shortened ca 1 cm and a new pocket for the oil-seal machined. (By shortening the brake mount original pocket for the oil-seal will be cut off).

Attached photo of shortened axle on both ends.

neptronix said:

That's pretty amazing for a geared hub. I'd love to see the bike in action.

I would bet that motor is very efficient due to the square-ish shape of the stator.. and that's why it make that insane power.

Click to expand...

Unfortunately, it is too cold and slippery to ride a bike at the moment in Lithuania. However, by downgrading my HubZila motor, I wasn't expecting to get such a good result.
I think that a wide and good quality magnets + enough of copper makes this motor a good performer.

Motor came in the mail... It's a beauty. GMAC10T.

It's mocked up in the photos below with just a few minor fitment concerns that I think I can solve pretty easily. The pin that holds the brake pads in the caliper touches the hub. I can easily cut a few millimeters off that. and the caliper needs to be adjusted to the outside a couple millimeters but there's no adjustment left in that direction with the IS brake mounts. Pretty sure I'm going to take the caliper to a machine shop to have the difference shaved off. And the derailleur is really close to the hub. I think it's going to rub on occasion perhaps in bumpy terrain if the derailleur gets shaking around much. If it's a problem, I think I'll just not use the biggest cog. Just adjust the derailleur limits to not go to the 34t cog.

Everything else looks really good. ...good enough to get the hub laced up.