Specialized Big Hit FSR with midmount

[Tench]

Been building this over the last couple of months and it is nearly finished now so i thought i would put some pics up, This is the bike as it was when i bought it;



and how it is now The motor is an HS3540 and a 40a controller running 6 x 6s 8000mah 30c zippy packs.





I have a few pics of it during the build so if there is anything you would like to see let me know.

The little block in the side of the frame infront of the seat is my series/parralel changer, when this is in to ride the bike the 3 permanently parralelled pairs of 6s 8ah zippy's are connected in series for 18s 16ah, to charge the bike this is pulled out which seperates the pack into 3 parralelled pairs and isolates them from the controller. Another block on the end of my charge cable from the icharger 306b fits in which connects the 3 pairs of 6s packs all in parralel to charge as a 6s6p 25.2v 48ah pack. The icharger can still balance charge the 6p groups through the d-sub connector, it works well, what a brilliant charger these are!

pics here;





The icharger putting 16a into the pack, this was me just pushing my 350w power supply to over 440w just to see how good it was!! i dropped the icharger down to 12a to keep it safe but atleast i know it has some power in reserve.



and the packs being charged connected to my harness before it was installed into the bike;



Got plenty more pics if there are any detials you would like to see.
Initial test rides have told me fitting the large chain wheels was not wise, the chain run is too high, when accelerating the rear squats because the chain pulls the swingarm upwards so i need to do some sums on the gearing and run smaller chainwheels, it is 48 driven/44 driving the rear wheel in the pics, 39/39 will give virtuall indentical gearing between motor speed and wheel speed but increase the pedal cadence 12.75% acceptable! and should reduce the squat which tends to induce wheelies!! especially when you consider the lowest gear is 40% compared to a DD instalation
I am quite proud of this one, i enjoy building them as much as riding them, all of this is home made in my little workshop, no cnc work at all!! all i have is a small chineese lathe, pillar drill and tig.

Just got to fine tune this one and then i can start on the next one, are Matt's 4" motors available yet!!

Simon.

[adrian_sm]

Awesome.

[knoxie]

Holy Sh*t

Thats freaking awesome buddy proper ebike porn you win game over

[snellemin]

DAMN!!! That is one sweet looking bike!

[full-throttle]

Wow

That looks great! Arguably better than an M-55

What kind of paint did you use? 2-pack? Looks sparkly

[Tench]

The paint is a plain orange but the laquer has red and silver flake in it, the hard part is getting and even depth of laquer over all the frame, not as easy as doing it on a flat panel! i dont paint, a friend with a paint shop did this, believe it or not he wasnt happy with it but i didnt want to wait while he did it again!!

[Jamzz]

Beautiful!

[GMUseless]

Holy balls. You're an artist man. Even the charger is gorgeous. Please, no more pictures. You're depressing the rest of us.

[chroot]

Awesome, This one is best ever I saw! Pretty sweet and beautiful ebike.




Pleeeeeeease take video action and I want see your ebike performance.

[kfong]

Nice work, i like how the mid drive motor is integrated into the frame. Nice saftey interlock.

[E-racer]

Mega nice man! I cant wait to get my bike powder coated/painted after seeing this. Beautiful!

[StudEbiker]

Wow, dream bike man. Fantastic work. Jealous!

[lostrack]

Well done mate - looks great!

Did you have to uprate the spring at all?

I'd love to get together for a ride if you're in the same part of the UK as me - I've got a little Astro 3220 setup and some great trails in Essex.

Tom

[dbaker]

No duct tape here Incredible craftsmanship you have shown You made your own series/parallel charge connector This is indeed a show bike and a hot rod

[kudos]

Can we see a pic with it's clothes off?

I'd like to see how you've fit the controller and batts in there....

Beautiful build by the way, let us know top speed etc.

Cheers,
Kudos

[Tench]

I think the spring will be fine, there is loads of adjustment, i am more concerned that the forks will need to have the springs changed or their preload increased, only some serious riding will tell me this and it is not quite ready for that yet.

Here are some more pics;

[knoxie]

OMG Wow!

Like most folks start with the bike then maybe 6 months later you get the picture, your just wham! there you go! beat that ha ha brilliant job, it looks amazing, your welding skills are top notch!! are you a pro welder? you have done such a nice job on this, it looks like a pro built bike and its certainly up there with the best build on ES for sure, take that Duck Tape!! awesome job!! you must be so happy with it?

Would love to see some video of it in action too ... love the colour as well, almost KTM orange with a hint of bling, really nice! I wonder how much riding you have done and what you intend on doing with the bike, it certainly looks like a nice pedigree bike for some off road trail riding or green laning, not to mention posing on down town!

You have pretty much laid down the fattest gauntlet when it comes to mid hub motor mounts, I haven't seen a nicer one ever!

[stripedtuna]

I'm speechless..

What an amazing peice of work. Does this forum give out trophies for winning efforts such as this?

You're a gold medalist mate..

Seriously.. well done..

Ed.

[Tench]

Knoxie, been trail riding ice for 40 years all over the country, had loads of XR's and KTM's, done some competition riding and even built engines and chassis that have raced in the IOM aswell as worked as a spanner man at british and world supermoto for the then multiple british champion Sam Warren. I was a pro welder for 18 years but that was mig, tig i just play at it. , so i supose i have all the skills to do this type of stuff, the electric side i am learning fast. This bike will get some serious use up in the Derbyshire peak district when it is finished, just got to make a new hub to fit on the Cyclone crank freewheel so i can get some nice crank sprockets of a better size. I will get some pics of Sam on this bike when i see him next week and some video when it is completely finished
The idea came from owning my first build a cyclone, link to that build below, and then a Stealth Bomber, the Bomber was ok but the weight of the DD X5 in the rear wheel was just too much unsprung weight which was not to my liking, so a mid mount hubbie it was as the cyclone was just a bit lacking for a serious off roader.
This weighs 85 pounds at the mo, might get another pound or 2 off it yet, which is a heap less than the Bomber, i can carry this one!! with much lower unsprung weight, better weight distribution and about the same speed but the ability to run lower gears for climbing.
I would like to do something with a big RC motor next, i allready know how i am going to do it

Simon.

[kfong]

Excellent job with the batteries, totally enclosed and with a cf plate as well. No fire hazard to worry about. I hope you provided some vents just incase. Makes me want to do a mid drive with a BMC motor and Nuvinci hub. Damn, I have too many bikes already. You have a very well thought out design. One of the better buillds I've seen on ES. That bike should rock in the trails.

[knoxie]

Knoxie, been trail riding ice for 40 years all over the country, had loads of XR's and KTM's, done some competition riding and even built engines and chassis that have raced in the IOM aswell as worked as a spanner man at british and world supermoto for the then multiple british champion Sam Warren. I was a pro welder for 18 years but that was mig, tig i just play at it. , so i supose i have all the skills to do this type of stuff, the electric side i am learning fast. This bike will get some serious use up in the Derbyshire peak district when it is finished, just got to make a new hub to fit on the Cyclone crank freewheel so i can get some nice crank sprockets of a better size. I will get some pics of Sam on this bike when i see him next week and some video when it is completely finished
The idea came from owning my first build a cyclone, link to that build below, and then a Stealth Bomber, the Bomber was ok but the weight of the DD X5 in the rear wheel was just too much unsprung weight which was not to my liking, so a mid mount hubbie it was as the cyclone was just a bit lacking for a serious off roader.
This weighs 85 pounds at the mo, might get another pound or 2 off it yet, which is a heap less than the Bomber, i can carry this one!! with much lower unsprung weight, better weight distribution and about the same speed but the ability to run lower gears for climbing.
I would like to do something with a big RC motor next, i allready know how i am going to do it

Simon.

Hi Tench

Yes looking at the quality of the welds it was fairly obvious you had a bit of welding experience! ha ha (I am in the crane industry) albeit on the electrical side our place does a fair bit of welding again super nice job on the bike, its pretty much exactly right IMHO a perfect mix of parts. I love going off road, I have an XT600 however you are limited to just the byways and a lot of them are getting tro's on them however technically you can ride an electric ebike on them even if they have been tro'd, the law says prohibited use of mechanically powered vehicles, so maybe a gray area (get a 250W sticker for your motor!!)

I have been thinking for a while to make an electric green laner if you like, this is perfect! the motor and batteries are nicely out of the way letting you hit some (not all) of the deeper puddles, you never normally go over 15-20 mph when laning anyway and you are going to make hardly any noise compared to gas bikes (easier to pull out of the mud if you get stuck too)

I saw you were disappointed with the bomber, that's a shame as I love that bike but do understand the weight in the wheel isn't for everyone, this build of yours can really show what you can do if you put your mind to it, I cant wait to see more pictures and for sure the video will be awesome!! seriously you could make and sell these bikes!! if there is a market for the Bomber and the Optibike then there is for one of these for sure.

If you have more build photos please post them and if you need another camera man for some video then give me a shout, where abouts roughly are you in the UK? I am in North Oxfordshire.

[binlagin]

This is the sexiest bike I've ever seen.... I'm jealous

[Tench]

I was'nt dissapointed with the bomber, it is an awsome bike, but it does have a very heavy back wheel, i just thought i could do better for the more technical type of riding i like to do With DD hubs their limit is easily found on the trails, wheel rotation is often too slow to make good power and they are heavy on the watts in these conditions, a 20" wheel is an option but the tighter radius doesnt ride the rough as well as a larger one so it had to be a midmount.
I have to work on the throttle responce on this bike, it comes in a bit too fast to confidently use the lower gears on rough ground, the new chain rings should help aswell by reducing the squat which emphasises the problem, i have adjusted the shock mountings and settings this morning which has helped aswell.

I am in Derby, very close to loads of trails, a friend was the derbyshire TRF group runs organiser so i have access to all the maps of the country but i know most of the derbyshire stuff by heart anyway. We have done some awsome rides in the peak district, yorkshire, the lakes and wales over the years, we even had Blez come and stay with us who did a feature for Trail bike mag on the peak district trails (TBM issue 57 may 2000) he also did an artical on some baffles i made for the DRZ.
Yes electric for the trails is what i had in mind as loads of them have been TRO'd round here. With what i learn from this bike i should be able to make my next one even better, lighter in the motor department, more powerfull but similar overall weight carrying more batteries. And i will take into consideration cost effective production when designing it.

A few more pics cos i have them

The left side of the motor showing the new bigger O/D alloy spindle with larger seals and a spacer to protect the upgraded phase wires;



The right side showing the out rigger support bearing inside the sprocket carrier, side cover has the thread changed to L/H 30x1mm so it tightens when the motor is driving with a southpaw (lefthand) bmx freewheel (Ground down from 1/8" to 2.00mm for the 7 speed chain)
Pedal crank spiders have been used as the torque arms/motor mounts.

[pdf]

This is one for the hall-of-fame. It is, for me, one of the most impressive builds and incorporates several features hard to find in one bike:
1) it drives the gears. Really nice for serious hill climbing efficiency.
2) it uses a hub motor so it will be extremely quiet; no reduction gear whine.
3) it protects the motor
4) it integrates all the heavy components into the middle of the frame for good balance
5) it still looks like a bike; a heck of an awesome bike, but a bike.
6) it looks awesome.

Numbers 2 and 5 mean you will be able to ride it anywhere a bike can go and not get unwanted attention. This bike is flat-out one of the best implementations I've seen. I really like the hub motor to keep down the gear/chain noise. Awesome.

PS: And FTW with that charger setup. Now you are just showing off ... Mad skillz there.

[Justtoby]

I knew you had something up your sleeve but did not know it would be this good. Congratulations it looks amazing.

Nice to see such fabrication skills. I hope to see a vid of this in action.

I love the charging solution, it looks very plug and play which I think is important for usability.