Electric Girvin Basman

[Callumrexreid]

Hello guys, this is my first post.
For the past 18 months I have been enjoying reading all of your posts and building an ever engrossing enthusiasm for the e-bike/ratrod bike community.
There's nothing quite like a good obsession as it quietly takes over every spare brain cycle.
A good obsession to me is like your favorite duvet, crisp, comforting and all encompassing.
I am now at the point of no return.
Last week after months and months of research, deliberating over parts, construction methods and aesthetics I have finally decided to take the plunge.
The bike I am looking to build will be a wide wheel electric Girvin fork Basman.
I will be attempting to achieve something that is both 'good looking' and effective.
To do this I know there may be compromises that will have to be made for this reason I want to make it clear that if and more likely when I have to make those compromises I will ere on aesthetics over function.
This is not because I necessarily think function is less important that aesthetic, it is because I believe it is the best way round to do it if you want something both beautiful and effective.
Get the look and feel right, then engineer the solutions that can uphold the design.
At least this way the engineering challenges will have a clear goal...
So this build will almost certainly be inherently flawed... I see it as more than a sketch than anything else.
Here is a brief description of my 'flawed' plan so far

- Basman Frame ~Regular (arrived)
- Girvin Fork (widened to fit 24x3 on 100mm rims and disk brake mount attached) (full breakdown of my endeavors on this mini build to follow)
- Crazy bob 24x3 front and rear 100mm rims on both
- The crown motor on rear
- Sinewave controller
- Lipo batteries etc

The bike will be mostly black with key elements copper plated such as front forks, seat post, handlebars and disk breaks.
I feel this build will take me the best part of 6 months in my opinion, hopefully 4 months so I can take in for a summer ride in the English country side this year!
Updates will come every weekend if everything goes to plan.

Good to e-meet you all and look forward to your help, advice and comments.

Best

Cal

 

[Callumrexreid]

Fork has arrived.
Frame on Monday.

 

[SkyknightJohn]

Welcome to the Sphere, and the obession. The Basman frames are beautiful. Sounds like you have a good plan. Good luck! I look forward to seeing your project take shape.

PS, It sounds like you're in England, but if you go to your profile and list your location it will show up on the right for all your posts, saving people time asking where you are and make it easier to help with localized suggestions when you have questions during your project.

 

[Callumrexreid]

Thanks for the words of encouragement
I've added my location to my profile.
I'll be doing a test of 24 x 100 rims with 24 x 2.35 crazy bob tires and then 24 x 3 berm masters would it be useful for me to take pictures for anyone else that may be in that particular dilemma?
If so where would be the best place to post, should I post it as a completely new post?

Best

Cal

 

[visuthdy]

Looking forward to your build. I've been looking at the basman frame myself. Do you know what size the rear is? If it's 170mm I can reuse the wheelset of my fat bike. I hope the frame can 26x4 tires

 

[CEGB]

Ahh, a fellow Englander... I look forward to seeing how this turns out. I had to google "Basman" though. That's an interesting frame.

Its also an interesting and non conventional fork choice. I approve....

My own project is starting shortly, a more ordinary GNG / LightningRods powered hard tail MTB, but fitted with a set of these CNC'd aluminium & carbon fibre beauties...


This will join my other oddball creation, powered using a more conventional and rather wheezy power source. Me;


What can I say, I like linkages...

 

[Callumrexreid]

Looking forward to your build. I've been looking at the basman frame myself. Do you know what size the rear is? If it's 170mm I can reuse the wheelset of my fat bike. I hope the frame can 26x4 tires

Hi Yes - I'm not sure exactly how wide the rear is, I'll get a tape measure to it and tell you tomorrow.
What I do know is that it absolutely can fit 100mm rims.
Best to use 24 x 100mm wheels as this gives you a range of tire choices from 2.5 to 4.5 inches
It is possible to fit 26 x 100mm wheels but you then get limited to using tires no bigger than 3 inches or so or they wont fit. This gives you a very cool low rider look but can be hazardous as you are stretching the tire over a rim wider than its design intends...

Something that I am doing tho ... lol

 

[Callumrexreid]

Ahh, a fellow Englander... I look forward to seeing how this turns out. I had to google "Basman" though. That's an interesting frame.

Its also an interesting and non conventional fork choice. I approve....

My own project is starting shortly, a more ordinary GNG / LightningRods powered hard tail MTB, but fitted with a set of these CNC'd aluminium & carbon fibre beauties...
View attachment 1

This will join my other oddball creation, powered using a more conventional and rather wheezy power source. Me;


What can I say, I like linkages...

Love that fork!
I am also a massive fan of linkages It has a retro yet modern 'look' kind of mechanical yet futuristic, great.
Big fan of that bike pic? I've never seen anything quite like it. Brilliant

 

[Tench]

I approve of the fork, there seems to be a lot of interest in these lately, i have a similar set waiting to go onto something!



.

 

[Callumrexreid]

Looking forward to your build. I've been looking at the basman frame myself. Do you know what size the rear is? If it's 170mm I can reuse the wheelset of my fat bike. I hope the frame can 26x4 tires

Regards the rear spacing, I'm afraid its 135mm only.. Measured it today.

 

[visuthdy]

Cal,
Thanks for checking for me. Too bad I can't reuse my wheels. Please keep us posted of your build with lots of pix.

 

[Callumrexreid]

So... got frame! beautiful design... Its raw as I may be doing work to it, I'll powder coat it matte black afterward.
Very thick rear fittings (euphemism not intended), which is good...
I still plan on reinforcing them for torque and perhaps a carbon fiber wrap as well.
See how it goes.
Major work, dissembling, cleaning and widening the Girvin fork to begin this weekend.
Will keep you all updated with pics along the way.

Best

Cal

 

[Tench]

I can see this with a brown Brooks saddle and pulled back flat bars!! Whats your plan for it?

I bet there will others as well as myself interested to see how you widen the forks, take some pics when you do it.

 

[AussieJester]

I like the Basman frame in fact I liked them so much I copied one!

Full thread can be seen here
built from 4130 chromo with a few modifications on the standard Basman.
handles like it's on rails right up to 95km/hr .. runs a rewound Turnigy 120 powered by
72v 40c Lipo driving through a ThuDsteR two speed dog box, Kelly controller and magura throttle
provide butter smooth throttle control...anyways,

Thought it might be of interest...best of luck with your build **subscribed!**

KiM

 

[Callumrexreid]

I can see this with a brown Brooks saddle and pulled back flat bars!! Whats your plan for it?

I bet there will others as well as myself interested to see how you widen the forks, take some pics when you do it.

My plan at the moment is to have fairly low profile 100mm x 24 inch wheels, front and back.

I'm looking to fit the crown motor on it, but it will be a squeeze as the the rear drop outs are only 135mm. So it might require frame modding... 140mm recommended from crytalyte... Whats 5mm between friends? Either way I'm going to reinforce the rear dropouts... not that they need mind.

Im looking to get the weight as low as possible on this bike, so batteries etc between the bottom bracket and the rear. (by low I mean in 'height')

Everything on the bike is going to be as low slung as possible so the seat post will be cut down so that the seat rests just on top of the rear wheel.

Motorbike handlebars of course and the tank is going to be situated on the central bar instead of above it, the tank will cover the controller etc instead of the batteries which will be lower still.

The tank and battery covers will be made from carbon fiber and will look to move the air from an opening in the front over the essential electric components that could do with cooling.. I will be mocking up my designs on the actual frame in cardboard etc.. before I finalize them.

The front Girvin forks, handlebars and maybe a rear mud guard will be taken to be copper plated.

The rest of the bike will be powder coated black matte.

Front and rear disk breaks maybe black anodized?

Basically black with details in copper.

Well that's the idea so far...

 

[Callumrexreid]

I like the Basman frame in fact I liked them so much I copied one!

Full thread can be seen here
built from 4130 chromo with a few modifications on the standard Basman.
handles like it's on rails right up to 95km/hr .. runs a rewound Turnigy 120 powered by
72v 40c Lipo driving through a ThuDsteR two speed dog box, Kelly controller and magura throttle
provide butter smooth throttle control...anyways,

Thought it might be of interest...best of luck with your build **subscribed!**

KiM

Great Build
Really inspired by this.. I'm going for a very similar philosophy of keeping the weight as low as possible (height wise)
Only big difference for me at the moment is I'll be hub based ... (in future I will move to something mid drive tho)
My front fork will be low on the wheel, keeping the whole thing very low profile, and fat (probably unsafe) tires.

If the uber wide rims and low profile tires dont feel safe enough, I iwll move to 80 mm rims with 3x24 to be on the safe side... we will see.

 

[CEGB]

Some further inspiration for you.

A chap on the MTBR forums who had a slightly earlier version of my carbon/alloy 'Look Fournales' linkage forks, a lot of spare time and a friend with a CNC milling machine has widened, and lengthened, (sp?) them to accommodate fat tyres on 26" rims...

http://forums.mtbr.com/fat-bikes/fatty-look-fournales-suspension-fork-843221.html

Chunky...

 

[Callumrexreid]

Hi Guys sry that I've been radio silent for a bit, been moving house.
In the mean time a few more pieces of the puzzle has arrived.
I put together my front wheel. Robs'son 100mm x 24 on xtrawide front hub, black spokes and crazy bob tire.
The crazy bob is only 2.35 inches so it makes for a very pleasing low profile racing fat look.
The tread is over the whole tire and it feels very robust.
If you are going to over stretch your tire for the same look, I would advise on something similar as crazy bob - the construction of the tire remains the same over the whole surface.
Other tires may have tread only on the part that has been designed to be in contact with the road, given the same over stretch treatment and the more vulnerable sidewall of the tire may cause weaknesses when in contact with the road.
One issue that I will flag up now, is that I am not too impressed with the build quality of the Robs'son rims.
I chose them because I really like their flat profile rather than the bumpy profile you get from Rigida rims of the same size.
They are single wall, which may not of been the best idea and now that they are in my hands the manufacturing seems a little flimsy, joins not meeting up perfectly not too happy.
So I will end up replacing them with the more solid Rigida rims.. My first aesthetic casualty.
On the other hand my TC Motor has arrived.
Very nice!
I got the TC80 as a happy medium. Very good build quality, and appreciate the cloth bag it comes in, nice touch.
Looking forward to building this into a wheel.
This really does need double wall rims! and heavy spokes too, it just exudes power.
Next weekend you should see a full assembly of both wheels, frame, motor and handle bars - even tho there is a long way to go, its really feeling like the build is passing a very significant hurdle.
From imagination to a collection of parts then to an actual bike!
.... albeit in need of quite a few parts

 

[Callumrexreid]

Ok so here is the disassemble of my 20 year old girvin fork.
I am going to widen the fork to accept 100mm rims with disk brake and 24 inch tires.
Because of the 24 inch tires there is no need to lengthen the fork.
Thanks to the way the girvin fork is constructed it looks like all I will have to do is replace the two rods that the fork tubes are attached to.
The replacement rods will need to be longer and will require a spacer of sort as well.
-
This is part one and it shows everything that has to be taken apart for you to remove these two rods...
It is important to document all of this for reassembly purposes as it helps with remembering which screws go where, washers etc...

 

[Callumrexreid]

So bit of an update to anyone following.
//
I should get the two rods replacements fro the Girvin Shock this week!
The last major hurdle is getting spokes for a 24x100 rim to fit with the crystalte TC motor.
Crystatlyte have said it will take 2 weeks to get me some spokes.
This is a bit better than I had hoped for because I was initially planning on buying 26inch rim spokes, cutting them down and re-threading, laborious but doable.
Currently they only make their 'bespoke' spokes for 26 inch rims (according to the EU HQ)
So finding out they will get me spokes that fit my rm 'off the shelf' was a surprise.
I have also ordered Ace motorbike handlebars that are low and swept back should suit the tire profile.
Cleaning the Girvin fork is taking quite a bit of time, disassembling and sanding by hand before sending parts to be plated and the headset has been a bit of a challenge.
The Girvin Vector 2 fork that I have has an integrated thread (instead of a star nut) is 1 inch and a stem that is attached to the suspension mechanism.
This means that I need to use shims to fit into a 1 1/8th headset/headtube and will be forced to put quite a few spacers between the headset and the stem.
I should be less than two weeks away from a full bike of sorts - well two wheels, handlbars, frame and motor.
Still a long way to go tho

 

[spinningmagnets]

Take lots of pictures of the entire build process...you never know when someone will want to write an article about it!

 

[Callumrexreid]

Take lots of pictures of the entire build process...you never know when someone will want to write an article about it!

Hi, yes I will.
I'll be uploading a boat load tomorrow as I've just got back the two rods from the precision engineer (Stewart Precision Engineering Ltd... really great guy. known him for a while and highly recommend if you live near by - Brighton/England)
This means I can put my fork back together and view it on the frame with the front wheel.

Can I just say that electricbike.com has been one of the key sources of inspiration and information for me. I point people to it on a regular basis and am very grateful for the great work that you guys do.

Please keep it up as you will always have an avid fan/reader in me.

Best

Cal

 

[danjpendleton]

Choppersus.com sells wide double wall rims. Im using 26x3 rims from them on my boardtracker ebike. They were $220 shipped in the states. Im using 2.5 maxxis hookworms for a bit of stretch.

Theres a misconception that you need to use heavy gauge spokes on ebikes. As long as you use quality 13/14 gauge spokes and the wheels are built properly, youll be better off.

I like your front fork, that basman frame, and your wheel setup. 2.35" schwalbe on a 4" rim is downright awesome. I have some 2.125" kenda tires kicking around. Maybe ill stretch them on when my hookworms wear out.

Keep up the good work!!!

 

[Callumrexreid]

Hi Guys.
Thanks for the words of encouragement.
Its really starting to come together.
Below is a picture of the Girvin Fork with the two rods replaced.
For anyone attempting to do the same, I made the new rods 48mm longer.
This means they fit perfectly on an xtra wide hub.
I will be disassembling this fork again, partly to continue the cleaning process but also to weld a disk brake attachment and remove the old brakes.
(NB 48mm xtra rod length works if you are going to make the fork work with disk brakes, not sure what length you should go for if you were intending to use the traditional brake attachments on what would have to be a 4x26 inch wheel.)
The other pictures show the parts coming together, at this point I'm feeling confident that this going to come together well.
Touch wood...
Tomorrow I will be putting together the fork onto the frame.
This is no easy process as the frame has a 1 &1/8 headtube and the fork's stemtube is 1 inch.
Chris King does a very good headset called the devolution that can accommodate this difference between fork and frame.
However I will be using head tube shims to reduce to 1 inch and use a 1 inch headset thereafter.
This will still leave a large gap between the top of the headset and the stem.
You should note that when using one of these Girvin Vector 2 forks you can not lower the stem as it is an integral part of the suspension.
I'm cool with this, but this might not suit everyone.
The other weird thing about this fork is it has an integrated star nut of sort, so your threadless headset screws into the top of the stem tube.
I will post pictures to illustrate all of this tomorrow.
All in all I'm really happy with the look of this low profile fat girvin fork, its really looking the part for me.

Best

Cal

 

[SkyknightJohn]

Looking good! It's coming together nicely. I had to look a couple times at the dropouts on the fork... they seem backwards from the norm... but from all the other pics it seems they're supposed to be that way. Silly me . Keep up the good work.