I'd like to build the perfect trail bike...

blitzwagen

100 mW
Joined
Oct 2, 2009
Messages
35
Location
sunny south africa
Hello all,

Firstly, thank you for the excellent ES community sharing knowledge and innovating so freely, we are all grateful.

I'm longing to build the perfect trail bike for attacking single track adventures. I have a few turnigy/Astro direct drive MTB and commuter
bikes under my belt which are great, but I want something seamless and inconspicuous for the trails around here. There's a strong anti-ebike
sentiment amoungst the hardcore mountain bikers here, I don't want to draw any unnecessary attention to myself, I just want to get up the steepest climbs
and preserver some strength for the downs.

The Specialized turbo levo FSR is probably the ideal bike for me for the following reasons:

1. The pedal assist is mature and completely seamless to the rider in operation
2. It's silent
3. The integration of the motor and battery pack is excellent, it looks pretty close to a normal mountain bike.

I'd prefer to build something though and I'm asking the community for ideas. The best midrive options appear to be the Tangent drive and
Bafang BBSHD. The Bafang is perhaps more visually conspicuous than I'd like and the Tangent is perhaps more audibly conspicuous. Is my perception
true, I haven't seen either in real life. I can handle basic
mechanical and carbon fibre fabrication, the reduction drive is beyond me though. Are you guys aware of any system (midrive pedal assist) that might
match the Turbo levo FSR for fit finish and noise that I can integrate into a high end enduro like bicycle?

Thank you for any useful comments,
Cheers,
Josh
 
Money as no object, imo there's no comparison in that situation to the best bike manu offerings- the stealth, integration, and the least compromise of bike characteristics are unparalleled.
For custom/diy/money, I totally 2nd the route of BBx and Tangent depending on the sound/power ratio you prefer. Personally, I like diy mid-parallel as the best combo of stealth/$/power. The one thing I'd prefer is less weight though. 40lbs @ >5kw would be awesome, so perhaps a direct mount tangent would be my second choice.

Sorry I can't add much contradiction/refinement, it seems you like got a good take imo. There are at least one or two people here that own both bbshd and tangent that might help. High end factory bike owners are even rarer though.
 
Thank you for confirming my thoughts on this. Hopefully somebody that's ridden a Levo and an ascent could perhaps chime in on the merits and riding experience of the two. Does anybody have any experience with the new Ascent PAS system?
I've excluded the Bafang because as I understand the system, it will not support proper torque sensing.
 
i think the tangent is noisy so that leaves you w/ the BBS02 or BBSHD. then your problem is getting a nice frame that fits the bafang with a GOOD chainline :evil: i've been riding some super-steep singletrack these days. you absolutely need a small chainring like 32/34T and at least a 42T rear cog, which aren't possible without a good chainline

most if not all of the more recent frames are pressfit like BB92, etc. problematic for the bafang.

then there are frames with suspension parts that interfere w/ the bafang. so i'm stuck w/ this shitty frame coz it's an old school 68mm threaded BB shell and has a swingarm design that clears the BBS02 very well

lWvGFlu.jpg
 
New frames are going back to threaded, so I hope going forward the pressfit/glue in BB nonsense will fade away.
 
Thank you all for the input. I've exlcuded the Bafang entirely because it doesn't have proper torque sensing. I have lots of high powered Astro ebikes posing at bicycles, it's fun for getting around but it completely destroys the feeling of cycling through forests silently and without killing my legs.

Still pondering the best solution.
 
blitzwagen said:
Still pondering the best solution.

Pedal maybe? If you can't climb it, maybe you don't need to ride down it either. It's not like you're doing anything important or time-sensitive.

If you want it to be easy, maybe you should get a mountain biking video game to play at home. Easy!
 
blitzwagen said:
Thank you all for the input. I've exlcuded the Bafang entirely because it doesn't have proper torque sensing. I have lots of high powered Astro ebikes posing at bicycles, it's fun for getting around but it completely destroys the feeling of cycling through forests silently and without killing my legs.

Still pondering the best solution.


i'm not sure if you really need torque sensing, it might even be a liability in technical singletracking riding i.e. might overshoot

what i do w/ the bafang is that i throttle and then i add human power on top of it, so everything remains predictable
 
I've just converted an all Carbon Scott Spark RC which under normal circumstances won't accept a Bafung type motor, but with a little saw and some mods to the carbon, I've changed the way the Bafung series integrates with the frame. Why the Scott, well its just about the ideal all round frame and 2013 26" frames are now worth well not very much such is the hype for 27.5 wheels ( ironically a 27.5 wheel will fit straight in but you can't run more than a 2.35 tyre ). Anyway with an electric bike you want to keep the COG down and the 26" wheel is ideal for this.

I was bitterly disappointed on the first ride with the standard settings but have since changed the whole character of the engine by firstly resetting the engines parameters to those available on other sites and then since tweaking them slightly to suit my style of riding. Is it as good as the Bosch system, sorry no, but I do get 1200W on the BBS02 750 and unrestricted speed + a throttle which no other OEM bikes have, at almost as good as ride. Basically you have to program the engine to suit your locality and style of riding. Its close to the Bosch standard but not quite there ( yet ). The upside of the Bafung is just how extraordinarily quiet it is. I fitted a high amp battery similar to the Luna mighty mini which sits discretely where the water bottle was. Gives about 1 1/2 hours of riding in fairly knarly climbs and single track. Do you really need anymore than 750W on this terrain, no I am mainly in the 43% power range and rarely need the throttle for a boost, you just need to use the gears like a conventional bike and its no problem. At the moment it is the limitation of the rider and his Cajones which is holding the bike back, not the power. I have done a lot of Enduro MX racing and I would guess in single track the Scott is on a par to a petrol 125. On the road is a different matter.

Yes you will need at minimum a 42T front ring and a 42T rear on the steeper stuff for no other reason, that steeper stuff is usually tight and awkward and slow is good, but slow spinning of the motor is oh so bad.
 
Thank you Wayne for your very useful advice fine tuning the bafang. I've found some articles describing how to improve the control and it's looking more promising.
I think that I'll have a go using a BBSHD on an enduro frame, it's worth a try without spending a fortune. Thank you all for your input.
 
Are you sure you really need the BBSHD, single track riding on a conventionally tyred bike ( the fat bike tyres have huge drag, have you ever tried to ride one off road ) is probably a little over kill. I just went the 52v route and it seems more than enough power and yet nearly 2kg's lighter than the HD. No its not a speed machine but more of a power aide to enable you to discretely ride in areas that elec bikes are probably not allowed. Silence and discreteness are what you want, not power to burn.
 
Waynemarlow said:
Are you sure you really need the BBSHD, single track riding on a conventionally tyred bike ( the fat bike tyres have huge drag, have you ever tried to ride one off road ) is probably a little over kill. I just went the 52v route and it seems more than enough power and yet nearly 2kg's lighter than the HD. No its not a speed machine but more of a power aide to enable you to discretely ride in areas that elec bikes are probably not allowed. Silence and discreteness are what you want, not power to burn.


XoPOdH8.png


my bbs02 takes me up pretty much anything so i have no regrets in not choosing the HD especially since the HD's chainline is so bad that it's not feasible to use a small chainring that lines up outside the gearbox. so w/ the HD you're pretty much stuck w/ the lekkie rings which are 42t i believe, not small enough for the climbs that i do

IMHO the reason to get the HD is if you want fast highway cruising for long distances and would like to tackle some moderate hills as well. the climb that i show here doesn't even get the BBS02 warm at all
 
blitzwagen said:
Thank you Wayne for your very useful advice fine tuning the bafang. I've found some articles describing how to improve the control and it's looking more promising.
I think that I'll have a go using a BBSHD on an enduro frame, it's worth a try without spending a fortune. Thank you all for your input.


let us know what frame you end up with. i'm also in the market for an enduro frame and it's been really frustrating finding one w/ a workable BB *AND* one that has ample space in the triangle for battery
 
Virtually all of the later Enduro frames are a no no due to the way the bottom tube is blended into the bottom bracket, all of the carbon frames are a no ( they have a very large radius around the bottom bracket which won't allow the Bafung to seat fully into the BB and the chain line then becomes to wide ) unless you know exactly how to modify them, the best to look for are pre 2013 frames such as the Whyte Ali series bikes such as the Whyte T129 which has won the XC bike of the year many year running, I have one as my day to day stead and love it to bits as a great all rounder
 
Guys sometimes things aren't always simple and you have to consider that you might have to think just outside of the box a little. No high end bike that I know has been specifically designed to take the Bafung engine so you need to first of all find a suitable BB that will be OK, next look for clearance so that the engine can rotate upwards enough to get ground clearance, minimum so that the engine is parallel to the ground, then check on suspension clearance, finally work out battery positions, remember it's more than likely you will have to have 2 smaller batteries such as the Luna Mighty Mini esq type that will fit into the relatively small triangle ( it's either a downward sloping top tube or risk clacking your cajones when climbing ) which is the option I went for, 1 battery on the bike and a spare in my backpack. To be honest I went high tech on the batteries ( Samsung 30's ) and have yet to completely drain a battery after 1 3/4 hours of riding so yet to find the limits.
 
Thank you for pointing out that the BBS HD is heavier and just not necessary, you're absolutely right, I need climbing power and not speed.
I've done a ton of searching looking at frames that are available here and I think that I've found promising options.
The Transition Patrol and Smuggler both have threaded BB's with modern enduro geometry. The older used versions of these
bikes also appear to have threaded 73mm BB's.
 
Ah with those two frames, how do you think you will be able to fit the motor if the bottom of the downtube is almost horizontal as it leaves the BB ( it can only hang downwards ).
 
Ened up building 15 bikes before I found my perfect trail bikes... just start trying different options as everyone has different needs

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Waynemarlow said:
Ah with those two frames, how do you think you will be able to fit the motor if the bottom of the downtube is almost horizontal as it leaves the BB ( it can only hang downwards ).


yeah that's a killer as well. you'll want a straight downtube since you want the BBS as high as possible

i'm beginning to think that it's futile finding the "perfect" BBS frame. i think i'll just weld up something like this and enlarge the downtube even more to hold the cells internally.

wGw15KL.jpg
 
have a look at bikee ebike motor or the eram (if it ever appears, manufacturer still seems to say it will at some point).

I think there is a massive hole in the mainstream market for something like tangent (i.e. well made and in frame) that is bbs quiet and torque sensing. fair enough most people on ES have a focus for massive power, but i think once you can provide something that is a retrofit to most existing bikes and lets people ride longtravel bikes on the flat like its whistler bike park you will have alot of adoption from the rest of the mtb community.
 
For all those still interested in good frame options, this is the direction I'm taking.
It's one of the neatest least conspicuous enduro like builds I'm seen on a really good frame, an early Santa Cruz Nomad. Thanks for all the advice thus far. I'll post a few pics when I'm done.
 

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Yeah, I found myself in same situation. I don't think there is perfect combo but it's getting there. Loudness was the biggest priority for me. If people can hear you from coming, it doesn't matter how stealth your bike looks. I had a cyclone before and was too loud. Tangent would be same or louder. Also, the loudness is enhanced more on the trail where it's quiet.

I ended up with BBSHD. It's very quiet. I got that instead of bbs02 because I know my style of riding is more abusive and handles more current. It's bigger than bbs02 though and more noticeable. I also have mini cube in saddle for more stealth.

That nomad looks like nice setup.
 
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