Ben bon bike

[Mathurin]

Baybystep towards upcoming bike, it's not yet where I want but it's going in the right direction. At least so far it's almost entirely made of electrons and (more importantly) pretend money.

Anyways I could describe it, but having spent several hours making these incredibly tedious spreadsheets, it'll have to do for now:

View attachment Bike26-10.xls
View attachment Bike700-5.xls

Edit: This spreadsheet will get updated over time.

Note that "??" means I've not yet actually weighed the component, some figures are guesses.

Insight appreciated.

 

[PaulM]

That's a very detailed spreadsheet indeed!! But, and maybe I'm missing something, where's the motor and batteries????

 

[Mathurin]

Motor is with the wheels.
Batteries are to be in a backpack.

 

[Doctorbass]

Hey Math... I can't see the place where you included the parachute in the list in case if falling down the cliff :wink:

No offence!..

Doc

 

[Jerome Daoust]

Mudguards...

Pour la slush au Printemps?

Jerome - ex Quebecer

 

[Doctorbass]

Mudguards...

Pour la slush au Printemps?

Jerome - ex Quebecer

ouais Jerome...... en Californie, y doit pas ben ben en avoir de la slush!!
8)

Ca te manque??

 

[Mathurin]

No parachute, actually I'm rethinking my wardrobe to minimize aero loss and then weight. Mostly my coat since it's worn out, but I'll pay attention to getting a slimmer fit next time I buy jeans, for example.

Mudguards because they're required for a bike to be practical, otherwise it's condemned to fair weather use. Planet bike Cascadia fenders because they have dual fender braces up front that should make it possible to adjust them so as to avoid snow compaction behind the fork as with Freddy fenders when riding through heavy sticky snow. But I have yet to compare several different makes of fenders, so as is they're just slapped on as a convenient space holder


Anyways it's still got quite a bit of extra lard at 13.6Kg, notably a good 1/4Kg chunk that can be chopped off by going threadless. But, the process of evaluating cost vs weight over so many parts is tedious monk's work. Thankfully, seems it's possible to use a spreadsheet to calculate cost per gram saved for potential parts/upgrades, kinky_cowboy put it this way:

It's easy to do yourself, just have a column (X) with the weight of your current part, a column (Y) with the weight of the new part, and a column (Z) with the cost of the new part. After that, it's simple arithmetic to get cost per gram saved as Z/(X-Y)

If you don't already have the first part, then you might want a column (AA) with the cost of the cheaper/heavier part, then the value of substituting the more expensive/lighter part is (Z-AA)/(X-Y)

Calculating this way, a lower number is better; for example, my 'best value' upgrade is to change my current 995g Mavic front wheel for a 770g Xentis Mk1 TT at £470, a cost of 470/(995-770)=£2.09/g saved, so I should prioritise that over swapping my DiaCompe BRS-200 calipers for M5 brakes at £4.29/g saved

So it seems like this should be the next step to take once I feel like getting around to it. But for now I'm a bit tired of playing with spreadsheets. Anyways I still don't have cash for this build so it can wait.

 

[voicecoils]

Comments on your bike spreadsheet:

Frame: If you don't score an old cro-mo mtb, consider a Surly or similar. My red bike is just that, and old cromo mtb BUT it's had the dropouts replaced with horizontal ones, a rear sliding disc tab welded on and the whole frame bead blasted and powder coated. If I started over, a new Surly would have been much easier, more component flexibility, more mounting points for racks brakes etc.

meter: I'd step up to the Cycle Analyst if you can afford to. You can get your controller connected with a direct plug in for it too.

connectors: what are powerpole x10's? I'm using 45A powerpoles, very happy with them.

Good looking list. The bike should come together nicely. What order do you plan on buying parts?

 

[Mathurin]

Hey thanks for the comments, It's funny you mention Surly because what I would have really wanted is something like a LHT, except with 26" wheels, since in my size it's made for 700 wheels. Closer to my means, older MTB's have pretty much what I want in terms of braze ons and such, plus frames from late 90's can go down to ~1.5Kg, and entire bikes are fairly cheap. Still, finding a good one in my size with semi horizontal drops appears to be delicate...

I started the spreadsheet with my Drain Brain on the bike, but it weighs 250g where a 70g Watt's Up would also let me guage amps used, add to that the Watt's Up should appear to be less of a wart due to it's smaller size. The controller seems headed to be an RC ESC since they're cheap, real light and seem ok for 48v systems. Also, by power poles X10, I meant ten power poles.

The bike isn't ready to start getting built, asides lack of money there's too many critical design elements I haven't settled on, such as colour scheme. I'm sorta at a standstill because many choices seem to have so many pros and cons that I have trouble taking a decision. Still, the first component I'll buy is likely to be a complete bike for it's frame, hopefully many of the other parts on it will be good enough to reuse. Once I've gotten that, I'd expect I'll make the rest come together pretty fast.

 

[voicecoils]

Hey thanks for the comments, It's funny you mention Surly because what I would have really wanted is something like a LHT, except with 26" wheels, since in my size it's made for 700 wheels. Closer to my means, older MTB's have pretty much what I want in terms of braze ons and such, plus frames from late 90's can go down to ~1.5Kg, and entire bikes are fairly cheap. Still, finding a good one in my size with semi horizontal drops appears to be delicate...

I started the spreadsheet with my Drain Brain on the bike, but it weighs 250g where a 70g Watt's Up would also let me guage amps used, add to that the Watt's Up should appear to be less of a wart due to it's smaller size. The controller seems headed to be an RC ESC since they're cheap, real light and seem ok for 48v systems. Also, by power poles X10, I meant ten power poles.

The bike isn't ready to start getting built, asides lack of money there's too many critical design elements I haven't settled on, such as colour scheme. I'm sorta at a standstill because many choices seem to have so many pros and cons that I have trouble taking a decision. Still, the first component I'll buy is likely to be a complete bike for it's frame, hopefully many of the other parts on it will be good enough to reuse. Once I've gotten that, I'd expect I'll make the rest come together pretty fast.

Cool. I can understand wanting to keep the bike weight under control, but I think some of the gram counting is a little crazy for ebiking. Having a durable ebike is safer and more sensible then a super light one IMHO. You might find light old frame, but race frames can have tubing walls so thin that they'll buckle if you lock the bike against a pole. My '02 Pinarello Prince has paper thin tubing and has to be handled like a baby.

You could always swap out some bolts for Ti versions to make up the weight and carry a cycle analyst

If you're going the RC controller route, just get the eagle tree logger, it weights next to nothing and seems awesome. If your running singlespeed and 26", what about a Surly 1x1? Only 3.4kg w/ fork

Is there a reason you're going for 26" over 700c? It might be easier finding light components if you go for a road frame, fork and wheelset. Also, will you go for a front or rear hub motor? I might have missed that...

Edit: Ah front hub. If your going for singlespeed, you might want to consider a rear Bafang, just screw on a freewheel sprocket or a track sprocket tack welded in place (no lockring threads on the bafang). Hmmm

 

[Mathurin]

Made a 700 bike with mostly parts I have laying around, A Miyata 600 and VS prestige, second spreadsheet added. The Miyata is much like the LHT, also ends up a lot cheaper to build up then the 26" bike since I already have a lot of the parts.

Think I've figured out a workable color sheme. Given ebikes have lots of extra stuff on them that make them look charged, Keeping everything simple should help. So the frame would be a dark color with everything else silver as much as possible, black cables, connectors, seat & grips, brass colored bell & nipples to match the accents behind the rolls saddle.

I'm looking at frames with braze ons, eyelets and semi vertical drops so as to mount fenders, rack & ss drive line, the lightest of MTB frames of the late 90's are unlikely to meet these requirements. So, I feel it's unlikely I would end up with an impractically under built frame. Although I've not weighed the Miyata frame since I don't have the proper BB remover tool, but if the fork is any indication then it seems the frame would end up around where the lightest mtbs would be. However, seems it ends up being pretty much a wash due to the wheels being heavier.

700 means narrower winter ties and no front motor so as to make for a 2wd bike. Tho it's a non issue with stiff thick mtb's, but I suspect having that much weight in the front fork would kill much of the road bike's smooth, comfortable riding qualities by preventing the fork from bending back and forth over bad surfaces. On the other hand a rear mounted bafang with an SS drive line and no rear brake would likely pass for a gearhub/brake, especially given a bike with fenders & rack.

I don't want to use a drain brain because it's too heavy for nothing as all I want is a means of keeping track of amps used, something dirt simple like a 10 led bar to show capacity left would be great. Eagle tree thing is nice, but the cost for weight gain over an What's Up makes it less attractive.

 

[voicecoils]

The Miata frame looks like a good candidate to me.

There are some things about your approach to weight savings that I just don't understand. The two weight saving measures that pop out at me are your concerns about the braindrain/cycle analyst weight and forgoing the rear brake. They just seem like strange areas to target.

If you don't want the extra features of the CA then a wattsup should be fine, cheaper and I suppose the lightweight is a bonus. However if you want it mounted to the handlebar you'll have to run your main battery power cables up to it. That will add weight and easily negate the difference between it and the CA. Probably end up weighing a fair bit more.

With your rear brake, is the extra ~200 grams really worse then flying over the front bars at 45kph? You can't ride the rear bafang fixed anyways as I'm pretty sure there are no lockring threads. If you were dead set on riding fixed, I'd say buy a disc compatible front bafang and install a IS 6 hole cog like THIS. The front bafang will have better spacing for a old road bike or track bike rear dropout anyways.

Another one is the choice of CC HV85. They're supposed to be great controllers but they're not immediate start (as they don't use the motor's hall sensors). They don't have a pre-made throttle that can be used. By the time you've made a throttle from a servo tester and a few other bits and pieces and boxed it up in a weatherproof enclosure, you'll probably be close to the weight of an ecrazyman controller without its aluminum case. Might be cheaper and easier just to buy an ecrazyman ditch the case and shrinkwrap it.

I think the best options for maintaining a light build are in the standard bike components: carbon fork, light weight wheelset, light tubes/tires, carbon/ti seatpost, 150g or less saddle (plenty of options), light cranks and pedals, lightweight bottom bracket, etc etc. It would be pretty easy to turn a 10kg bike into a 7kg bike to overcome weight of the bafang.

Then there's the matter of bafang gears stripping. See HERE.

Plenty to think about. I reckon you'll end up with a great ebike when it does all come together.