Photo guide (3 of 3) for 8Fun kit conversion of Specialized Hardrock Sport Disc

[IanA]

Part 3


Resulting in strangely shaped moulded fitting for pedelec sensor


Fitted parts back together when fully cured

(as before, will eventually paint epoxy resin matt black and should blend in very nicely but better to be white in photos for time being.)

Then refitted this after cutting the metal ring off and filing the sharp edges whilst leaving enough metal for the cable tie to hold the sensor in place. Also decided there was too much flexing of the pedelec disc so decided to add an extra blob of epoxy resin, drilled a hole for a cable tie and added an extra tie to hold it all firmly in place.


Meanwhile, new Avid 203mm rotor disc and 203mm post mount adaptor arrived.

This mod is needed otherwise there isn’t enough room for the hub motor with the original brake calliper mounting position for the original 160mm disc.

It also allows enough space between the spokes and the Avid brake calliper adjuster, but still only a couple of millimetres between them!


Next the controller housing and wiring.

There is a box supplied in the kit for the controller. It is suggested that it should be located on the seat tube, but the tube clamp on the box is too small for the frame on this bike and would interfere with the front changer cable so I decided to modify it.

First I cut off the seat tube clamp with a hacksaw


I later filled these holes with epoxy resin to seal it and to strengthen the now weakened box.

It was then a simple job to drill two holes in the box so that it could be attached by the secondary bottle cage mounts onto the seat tube. This was something I had not anticipated but worked surprisingly well. As before, I used a sheet of rubber cut from an old inner tube between the box and the seat tube to protect the frame.

I was finding it extremely difficult to screw in the connection to the battery – something that needs to be done every time the battery is put on or taken off the bike. The connector is almost inaccessible.

More epoxy resin required!!!

Extended the connector using electrical tape and cling film to protect the other parts


Removed cling film when set but left some electrical tape on a clamp that looked like it would be vulnerable in wet conditions.


Added a ring of rubber from an old narrow inner tube (lucky fit!) and that makes it very easy to grip. It’s now very easy to connect or disconnect the battery.


Fitted controls in place but disconnected and removed the thumb throttle as I don’t use it.

For me, the thumb throttle takes up room on the handlebars and it’s an extra wire to route around the bike. I reckon the best thing about an ebike is the pedelec sensor & if I put the bike in it’s lowest gear and turn the pedals I am unlikely to put any effort in whatsoever but the pedelec sensor will turn the motor on, so to my mind that is my throttle-only option.

Re-ran cables and neatened everything – notice the extra long cable behind the control box housing – this is the battery cable and it is about 1 metre too long! – I will shorten it when I’m totally happy that I don’t want to change the position of anything.

Cable connectors all fit inside the controller housing along with the controller but it’s a tight fit and I found I needed to place them inside very neatly for the lid to be closed.

Otherwise very little in the way of extra cabling to be hidden away – possibly a different story on a smaller frame!


Finished!



Problems remaining…

I really like the motor cut outs on brake levers but the kit only has a cut out switch attached to one of the two brake levers. This has occasionally caused me problems when I want to use the lever without the cut out on it’s own and it ends up working against the motor. I will try to find a solution to this if I don’t get used to it pretty soon.

The battery charger takes much longer to charge the battery than suggested. The manual says 3-4 hours and the longest I have charged it is just over 6 hours before I turned it off and went to bed. I was waiting for the charger light to go green but it never did, despite the battery showing the full 4 green lights after 5 hours. It also gets extremely hot as there is no fan in the charger and although this is to be expected it’s a bit unnerving to leave it running whilst unattended.


Weight…

The 23” bike was 14kg when it arrived and is now 21kg but I’ve still to add a pannier rack and some form of mudguards.


Shopping List…

23” Specialized Hardrock Sport Disc (2011) £440 from local bike shop. (Obviously I can’t vouch for how this kit will fit any other sized frame or bike!)
8Fun bottle battery 36V kit £435 incl. delivery via ebay.
Avid 203mm disc rotor £20 (on special offer) from an online bike shop.
Avid 203mm post mount adapter £9 from an online bike shop.
Bolts to fit post mount adapter (not supplied with adapter!) £1 from local bike shop.
Crank bolt allen key (8mm) £2.50 via ebay.
Crank removal tool suitable for Shimano Octalink cranks £6 via ebay.
Ding All 7” epoxy resin surfboard repair stick £11 via ebay.
100 pack of 4.8mm x 300mm cable ties £3.50 via ebay.

Total £928 (although I believe a computer is a necessity with an ebike to be able to either save power by going above the assisted speed or to easily cruise at just within the assisted speed to get full power benefits)
Other items that could add to the bill might be: helmet, pannier rack & ‘bag(s)’, mudguards, lights, pump & tyre repair kit, locks and basic tools… clothing… waterproofs… the list goes on…and on…and on… ££££££££


And what of the aim to have fun?...

Well, it certainly seems to be working so far…will let you know how it’s going after a few more miles.


(go back to Part 1)

 

[andyh2]

With your ingenuity, that's come together really well.

Out of interest is it the left or right brake lever that has the cut out switch? I guess in most of the world the RH lever is for the rear brake and the LH lever for the front, whereas normal in this country is opposite to that.

I too would be disconcerted at the charger heat, is it worth checking with them that it's expected to get so hot?

 

[IanA]

Hi andy

It's the RH brake lever but presume it would be fairly easy to move the switch to LH side or even simply to mount the levers upside down if anyone wanted it on the other side.

I have already asked the 8Fun people and got the following reply "you can disconnect the charger as soon as it is fully charged, but its ok to leave the charging a while after its fully charged (the light goes to green), just don't leave it too long after fully charged.So don't worry about it too much."

So I have asked for clarification!

 

[flecc]

Very nice job Ian, you'll feel justifiably proud to ride that bike.

 

[NRG]

seconded, very neat conversion

 

[eddieo]

Very nice looking conversion...I considered this kit, but went for the wisper Daahub in the end. My specialised crosstrail Ltd disc was a brilliant donor bike for conversion, I love it except for the seat!

fully understand what you mean re FUN...My new bike is the best FUN i have had in years.a much better riding experience then a heavier ready built e bike.....most dont even recognise it as an e bike which is helpful when riding fast!

 

[Oiseaux]

Inspirational !!

 

[Gogs]

Looks brilliant Ian, very neat job, you will have some fun with that bike now! You are inspiring me to get started with my conversion, still looking at options but your kit seems like good value.

Charging time seems far too long though, hope you get an answer from the supplier on that one!

 

[banbury frank]

Hi IanA

Congratulations on a job well done very smoothly fitted kit


Frank

 

[dmcgoldrick]

great detail...... thanks for sharing........some really good solutions to make the kit fit.

regards

 

[IanA]

Battery Unit Dimensions and Torque Washers

Here is a reply to a question I have been asked privately about the bottle dimensions and a torque arm. I thought it may be useful to others...

The whole bottle battery and mount is approx. 33cm long and the lower bottle cage mount hole is a slot with a centre that is about 13cm up from from the base of the whole unit. The circumference of the whole unit makes it just over 9cm wide on the bike and that with the mounting bracket means it is at most about 11cm from the frame. Sorry for the about/just over/approx. measurements but it's very difficult to measure now that it's on the bike.

There is no torque arm with the kit. It relies instead on 2 supplied torque washers which exactly fit these particular forks.

 

[John L]

Hi Ian

Very well done You've highlighted all the issues that arise when fitting a kit and dealt with them well. As you found out you do need to apply a lot of ingenuity to make a good fit.

As a matter of interest how well does the pedelec sensor work. Unfortunately my battery for the sunlova kit (now on ebay as 8fun) has gone for a third time. They have again offered to replace it which I'll take them up on - but I'm a little concerned as to why it happened again. Perhaps the controller, sensor etc that they provided you with combined with the new battery will do the trick. They want £60 for the new setup but it would be great to know that it worked well before I take the plunge

John

 

[andyh2]

Thanks for battery dimensions, that's helpful.

I'm interested to know about how the pedelec sensor works. Does it give you full power after a couple of turns of the pedal, or does it feed in power as cadence rises?

The once max power reached does it continue to give full power, however high your cadence, or does it reduce power as cadence goes over a threshold?

 

[Caph]

Ian, this is excellent work. In my eyes you've probably got the perfect hard tail electric MTB without breaking the bank. It's a shame these aren't available off the shelf. Specialized and 8FUN really need to get their heads together.

A couple of points - you can get away with a 185mm front rotor with Avid BB7s on the QSWXK, but I'll bet you get a load of extra stopping power with that 203mm rotor, it looks like it would stop a motorbike! Also, you'd probably find that you could fit the pedelec sensor as it was intended even on the non-drive side if you swapped to a 125mm bottom bracket. Finally, you might want to reconsider fitting the throttle, it looks like you've got room, and it will give you 17.5-18mph top speed.

I really love the look of your bike and the battery position is great. Thanks for sharing.

BTW, what are the forks on your Specialized?

 

[Jon]

Looking at all your wires, controller and handle bar mode switcher looks just like the set up on my Oxygen. I wonder if its a standard set up fom Bfang

 

[IanA]

As a matter of interest how well does the pedelec sensor work. Unfortunately my battery for the sunlova kit (now on ebay as 8fun) has gone for a third time. They have again offered to replace it which I'll take them up on - but I'm a little concerned as to why it happened again. Perhaps the controller, sensor etc that they provided you with combined with the new battery will do the trick. They want £60 for the new setup but it would be great to know that it worked well before I take the plunge
John

Hi John

All I can say is that it's working very well at the moment - I notice that your first battery worked just fine for 4 months and 1000 miles, so it's obviously far too early for me to comment on reliability especially since I have been on holiday for the last 2 weeks and haven't been out on it since my return!

Good luck whatever you decide.

Ian

 

[IanA]

Specialized Hardrock Sport Disc 2011 Full Specification

FRAME Specialized A1 Premium Aluminum, fully butted, formed TT, Double ORE DT, externally relieved HT, reinforced disc mount, forged dropouts w/ replaceable hanger, disc only

FORK SR Suntour SF11-XCM-V3-26-DS-MLO, 80mm, 1pc. alloy lower, 30mm Hi-Ten stanchions, mechanical LO, coil/mcu spring w/ preload adj., spring assisted seals

HEADSET 1-1/8" threadless, loose ball

STEM 3D forged alloy, 4 bolt, 10 degree rise, 25.4mm clamp

HANDLEBARS Alloy riserbar, 25mm rise, 8 degree back sweep, 6 degree up

GRIPS Specialized Enduro, dual compound Kraton, no flange, 131mm

FRONT BRAKE Avid BB5, mechanical disc, 160mm G2 Clean Sweep rotor

REAR BRAKE Avid BB5, mechanical disc, 160mm G2 Clean Sweep rotor

BRAKE LEVERS Alloy, linear pull

FRONT DERAILLEUR Shimano Altus, 34.9mm clamp

REAR DERAILLEUR Shimano Alivio, 9sp direct mount long cage

SHIFT LEVERS Shimano Acera SL, 8sp rapid fire trigger

CASSETTE SRAM PG-820, 8-speed, 11-32t

CHAIN KMC X8 w/ reuseable Missing Link

CRANKSET SR SunTour, Octalink spline

CHAINRINGS 42S x 32S x 22S replaceable

BOTTOM BRACKET Shimano BB-ES25, Octalink spline, cartridge bearing, 68mm x 118mm

PEDALS Composite platform, toe clip compatible, 9/16" w/ reflectors

RIMS Alex RHD 26", alloy double wall, pinned w/eyelets, 32h

FRONT HUB Forged alloy, hi/low flange, double sealed, ground race, machined disc mount
and flange, QR, 32h

REAR HUB Forged alloy, mid flange, double sealed, ground race, machined disc mount and flanges, cassette, QR, 32h

SPOKES 2mm (14g) stainless

FRONT TIRE Specialized Fast Trak LK Sport, 26x2.0", 60TPI, wire bead

REAR TIRE Specialized Fast Trak LK Sport, 26x2.0", 60TPI, wire bead

INNER TUBES Schraeder valve

SADDLE Specialized XC, Body Geometry, 143mm width, front and rear bumpers

SEATPOST Alloy two bolt, 12.5mm offset, micro adjust, 30.9mm

SEAT BINDER Alloy QR, nylon washer

NOTES Chain stay protector, reflectors, clear coat, owners manual

 

[IanA]

Ian, this is excellent work. In my eyes you've probably got the perfect hard tail electric MTB without breaking the bank. It's a shame these aren't available off the shelf. Specialized and 8FUN really need to get their heads together.

Thanks - that was pretty much the aim, especially the "without breaking the bank" bit!!
I reckon people like Specialized will realise that there is a market for this kind of ebike and they will respond but could take years or could happen tomorrow! That's one of the reasons I see this as a temporary solution to my ebike needs.

you can get away with a 185mm front rotor with Avid BB7s on the QSWXK, but I'll bet you get a load of extra stopping power with that 203mm rotor, it looks like it would stop a motorbike!

I don't know if there is any difference between Avid BB5 & BB7 dimensions, so can't say if 185mm rotor would fit.
The size of the disc was my most difficult decision. I contacted the 8Fun kit supplier and they said it needed to be 203mm so I decided to play safe (plus there was a special offer on the 203mm!!). Given that the clearance between spokes and the BB5 caliper with the 203mm disc is only 2mm I can only imagine that with the 185mm disc rotor the clearance must be less than wafer thin !

Also, you'd probably find that you could fit the pedelec sensor as it was intended even on the non-drive side if you swapped to a 125mm bottom bracket.

I did consider swapping the bottom bracket but I was concerned that the longer axle would mean the chainset would be out of alignment with the rear wheel cassette causing excessive chain wear and excessive noise so didn't want to risk it especially since it would have been extra cost.

Finally, you might want to reconsider fitting the throttle, it looks like you've got room, and it will give you 17.5-18mph top speed.

Might give it another try after I've got used to this - then I should be able to see if it feels better or not.

BTW, what are the forks on your Specialized?

SR Suntour SF11-XCM-V3-26-DS-MLO, 80mm, 1pc. alloy lower, 30mm Hi-Ten stanchions, mechanical LO, coil/mcu spring w/ preload adj., spring assisted seals

I have now also posted the full spec of the bike.

 

[IanA]

Cadence vs. no load speed test

Thanks for battery dimensions, that's helpful.

I'm interested to know about how the pedelec sensor works. Does it give you full power after a couple of turns of the pedal, or does it feed in power as cadence rises?

The once max power reached does it continue to give full power, however high your cadence, or does it reduce power as cadence goes over a threshold?

I've done a few no load tests for you and I found the results very interesting...

It takes half a revolution of the crank before the controller is activated and the speed at which the motor starts is dependent on the cadence of that half revolution of the crank.

It is then dependent on cadence - the slowest cadence that the controller will deliver continuous power is about 6 rpm and that corresponds to a no load speed of around 2.5 mph.

The highest speed is reached at about 40 rpm and there appears to be a smooth transition of speed dependent on cadence between 6 rpm and 40 rpm.

The 3 "power" settings do not appear to affect this other than limiting the top speed.

Since I haven't rigged anything up to measure the power being delivered to the motor I can't say if the power reduces as the cadence increases beyond a limit. As far as I can tell from riding the only reduction in power is a smooth transition as the speed of the motor approaches the selected limit (from around 12 to 15mph on the high setting).

So does this mean that when struggling up a hill you need to be in a very low gear so that the cadence is above 40 rpm, thus delivering maximum power? If so, are ultra low gears not only desirable but necessary. Or do the no load speeds I have measured not reflect the power being delivered to the motor?

Ian

 

[andyh2]

Ian,

That's really interesting. 40RPM cadence is actually pretty low for normal riding, I normally ride 65-80 and 'proper' riders are more like 90+.

My concern would be if it started to reduce power above 40RPM, but it doesn't sound like that's happening. That's good as when going uphill it allows you to spin easier gears at a higher rate which is usually more efficient and kinder on the knees.