revtothelimit - motorbike forum

With the Ducati nearly finished (HAHAHAHAHA...AHAHAHAHA...HAHAHAHAHA!) my thoughts are turning to my next motorised two wheel project...

A mate of mine out in Oz, Laurie, goes by the business name of Suspension Smith and makes a living developing unusual two wheeled suspension ideas. One of his ongoing projects is combining linkage and telescopic forks for off road machines....



..and he's also built a downhill mountain bike with the same front end design...



Now, I've got no desire to emulate his front suspension design but how he's made the frame is of interest to me...



Laser cut aluminium side plates with bolted in headstock, bottom bracket, stand-offs etc.

I'm looking at building a long travel e-mtb d/hill bike, that can be pedalled to the top with Mr. Bosch doing the hard work, using the same basic same frame construction idea.

Bosch gen 4 motor, 29" front wheel, 27.5" rear. Triple crown 200mm travel forks, adjustable offset yokes, adjustable +/-3 degrees head angle with head stock inserts, +/-30mm reach adjustment moving the headstock fore and aft, long and slack geometry, high pivot rear suspension with an idler sprocket (think Commencal Supreme DH), 240mm rear travel, adjustable seat angle, bolt on rear dropouts to adjust chain stay length, no welding - all CNC and bolted together.

Maybe crash it through the Hope catalogue for some garish anodized gee-gaws.....

This could be exceptionally interesting, or quite insane

I look forward to either

If you’re using that frame you could quite easily sandwich something like a bafang motor in there saving the expense and complexity of the Bosch stuff, great idea though

Why not do away with front and rear suspension and have one sprung and damped hinge in the middle ? Obv bars and seat connected to the same side of the hinge

Couchy wrote: Mon Jul 27, 2020 6:37 pm If you’re using that frame you could quite easily sandwich something like a bafang motor in there saving the expense and complexity of the Bosch stuff, great idea though

I need to find out if a member of the public can buy a Bosch motor and controller or whether they're only available to OEM's and how much it would cost. But the 85Nm the gen4 software update has unleashed sounds enticing...

Couchy wrote: Mon Jul 27, 2020 6:37 pm Why not do away with front and rear suspension and have one sprung and damped hinge in the middle ? Obv bars and seat connected to the same side of the hinge

Sounds like a brilliant idea...

The common damper and spring idea was tried back in the 90's, designed by Dave Smart (who markets himself as a misunderstood suspension genius who understands things that everyone else - McLaren, Toyota, Lotus etc. etc. - fails to grasp) and sold in very limited numbers under the Muddy Fox brand as the "Intereactive" and I think Harris Performance had a hand in making the frames....



...didn't work, or, if you listen to Dave Smart, everyone was too stupid to appreciate its magnificence and change what they expected from bicycle suspension.

Wow hmmmm

Regarding the Bosch motors only OEM van buy the whole kit which is why most specials go bafang, tbh bafang do some good stuff now.
I can vouch the 85nm update is very good, gives more assist at lower cadence too so n carry higher gears. Also on full power it’s a little OTT at times as it just wants to wheelie

Your friends front end looks very similar to a Hossack front end, Nigel Hill at Saxon also did a similar front end.

The aluminium plate frame is also interesting, been done in the motorcycle world by Heron Suzuki in the mid 80s, an RG500 engined race bike held together with Araldite

Julian_Boolean wrote: Tue Jul 28, 2020 7:55 am Your friends front end looks very similar to a Hossack front end, Nigel Hill at Saxon also did a similar front end.

It is a Hossack front end, but it's combined with telescopic forks so that you get longer travel and the different systems can be tuned to work differently to plat to their strengths so that you get a better complete front end

I hadn't noticed that it also had teles, interesting, could be really good if you could get it set up correctly, a lot of variables though for set up, there's going to be a really sweet spot with that front end, but it's going to be a bugger to find.

I'll bet you a £600 Voodoo Bizango rides better

Julian_Boolean wrote: Tue Jul 28, 2020 8:04 am I hadn't noticed that it also had teles, interesting, could be really good if you could get it set up correctly, a lot of variables though for set up, there's going to be a really sweet spot with that front end, but it's going to be a bugger to find.

Laurie's built in a whole mass of data logging and video kit into the frame, take a look at his faceberk page...

https://www.facebook.com/Suspensionsmith/

I designed the carbon frame that Team GB used in Rio - the structural carbon that is, the aerodynamic "A-surfaces" where all done by Cervélo but the internal structure was mostly mine - "mostly" 'cause I wasn't working solo, but it's deffo my baby.

Anyway - point is, I know a thing or two about bicycle frame structures, so I'm pretty interested to see how this goes. I'd be making it in Carbon of course, but Ally is definitely a lot simpler - and cheaper!

I recently posted links to Hossack etc in another thread, including bicycle suspension.

Edit: https://www.hossack-design.com/

His m/c design uses a simple welded trellis, no need for expensive NC cut metalwork, the bicycle is tubed:

https://www.hossack-design.com/copy-of- ... ntain-bike