Thorn Cycles Forum
Community => Thorn General => Topic started by: energyman on September 11, 2022, 09:44:24 pm
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Would it be considered sacrilege to fit an assistance motor to an RST ?
Just to help one with the hills of course.
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Would it be considered sacrilege to fit an assistance motor to an RST ?
Just to help one with the hills of course.
Well...ATMO ("According To My Opinion" as American framebuilder Richard Sachs is fond of saying in his online communications) I think if e-assistance will keep you riding out on the bike and enjoying much of what cycling is all about*...
Why not? :)
There are many options that don't add much in the way of weight or bulk that will give you a needed boost for hills...but they won't generally have the battery capacity/range/Coulombs needed for longer-distance use. I'll defer at this point to the greater expertise of Andre and other Forum members with more firsthand experience in e-Bike conversions.
All good luck; please keep us apprised if you forge ahead, as I think the final build will be really interesting. The RST is a pretty light platform so the final e-Bike should feel pretty lively.
Best, Dan.
*"Digital" electrification vs "analog" pedaling? I remember reading of similar pushback in the bicycle community when early derailleur drivetrains replaced Fixed-gear flip-flop hubs in road racing. It was thought to be "cheating" when the "father of touring", Velocio, pioneered the field. Soon every bike in the peloton was so equipped. I keep and ride a Fixie on occasion for its simplicity, its unmatched use as a device to get into shape quickly, to keep my pedaling technique honed and to get back in touch with how cycling was "at the beginning" of Safety bikes. It is elemental fun but ill-suited to vast changes in terrain that are a doddle on geared bikes.
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I know some may consider it heresy, but there's nothing religious about cycling, even if Thorn consider they've written a Bible!
Neither do I subscribe to the idea that E-bikes ought to be restricted to those that need them. They can be very useful in that regard, I know several people that would no longer be cycling if they didn't have that E-assistance. But there's also, even amongst those that consider themselves cyclists, a growing appreciation that sometimes it's nice to have the choice and the idea that they're cheating seems to be diminishing. I've never understood just who it is anyone thinks you're cheating.
So yes, if it's practical and gives you something you want, just do it. On the practical level, the bike might restrict the options, the Rohloff excludes a rear hub motor and the EBB would add complication to a mid-drive (I haven't done it so I'm not even sure it's possible) That just leaves front wheel drive, which I know nothing about, though it seems to work well enough for those who do.
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Thorn do appear to offer conversions to some of their models using the Pendix system. Not cheap and the RST is not mentioned but maybe worth discussing the possible options with them.
https://www.sjscycles.co.uk/ebike/pendix-motor-kit-300w-long-reach-magnet/
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If the conversion keeps you cycling, I don't see that ideology or even religion comes into it.
You may be somewhat limited if you want to keep a Rohloff or derailleur setup at the back, and the eccentric bottom bracket keeps you from using a central motor with a Rohloff, unless you want to add some manner of chain tensioner.
You used to be able to get rear wheel hubs with clusters of gears on them for derailleur use, and may still, but they were the most unsophisticated of all the early electric motor installations but also the most brutally efficient. I mention this because theoretically a rear installation reduces the mess of wires that are -- believe it or not -- the biggest practical bother about fitting your own conversion, and can also be ugly on a careless conversation commercially done. Note the "theoretically"...
All of that said, the easiest fitment and the easiest wire-tidying job among my electric motors has been with a full kit from the British Bafang/8FUN importers for the front wheel. By contrast, fitting the Bafang/8FUN central (bottom bracket) motor was a nightmare even with some of the electronic gubbins contained in the motor case itself -- until I got smart and instead of trying to wire tidily, I started thinking laterally and simply folded and refolded the surplus wiring until it would fit in one of those office computer spiral tidy cables, which conveniently come in neutral grey and black. I had the grey and that fitted well with my BRG bike. All of this par may sound a bit over the top, but it's the trickiest part to get right if you're getting on a bit and trying to limit bending over the bike. It isn't any more difficult really than fitting an n'lock (which nearly gave me a stroke the day before going in for heart surgery) or getting a Chainglider onto the chain and gearwheels the first time without ripping it apart or tying it into knots.
Here are some tips, discovered to be important by the questions people on the British pedelec forum asked me either on that forum or to my private mail:
1. Yes, you can fit any position electric motor yourself (as wheel hubs rear or front, as a centre motor), if you have a full kit, otherwise you risk an unfinished project. This is given on the assumption that you have removed and replaced a wheel and a bottom bracket before, and that you know that electricity flows in two or more wires which are different, usually not only in function but in colour.
2. I believe that in the UK there is a power limit on the size of motor you can use on the public roads. You must absolutely be satisfied that the low-watt motor you are forced to buy has high torque, or it will not be satisfactory. This isn't as difficult as it sounds because there is no standard by which pedelec motors are measured: the authorities take the word of Chinese(!) manufacturers, people who've been trained by their government on threat of existential penalties to tell them what they want to hear, a skill easily transferred onto customers! One reason I stick to Bafang is that they have a lot of experience with high torque motors from the years when the BPM (a hillclimber as in competitions) was their big seller, and the UK-legal Bafang motor I had on the front wheel first to give me some perspective on a new field is commonly referred to as "the little BPM".
3. A common complaint from the people who stop me on the roads or in the supermarket to ask if I want to sell them my bike -- which is clearly by its longevity (it's now thirteen years old) a riotously successful installation -- is that the electric bike they have, which stands idle in the garage, doesn't carry them further than the shopping. They've made the three most common newbie errors in electric bikes: They specified the battery too small, they expected the battery to do all the work, and they didn't look after the battery. I've never once run my battery for more than half its storage capacity, I charge the battery the minute I get home, even if I rode only a kilometre to the shops (I find that these days I'm better balanced on my bike than on my feet), and I specified the battery at a humongous 14.5kWh, at first glance far outside my requirement, but in practice hardheaded common sense and careful calculation from experience. My first battery, from the trial front wheel installation, is still running and good, probably fifteen years old, and would have been enough for normal rides on the new motor, delimited by how soon we run into a river at a quay somewhere, where there's no bridge to get to the other side, say 20km away, not very far for intermittent use of my first 8.5Ah battery. But you don't specify your battery by the shortest or the average ride you take, you specify it by the longest ride you take say once a year, in my case 60km, beyond which I use a car or the bus. That was when I used the motor very lightly. Now, unfit after the pandemic, I use it more and think 45 to 50km will be about right on my current usage of the motor, to leave it half full on my return home, where I recharge it immediately and let it trickle for an hour or so after the light turns green; that is the most vital piece of information I have to impart. The battery will be 40 percent to half the cost of your electric installation, and how fast it is consumed is up to you, so take care in your calculation and when you start using it to give it all the attention it deserves.
The motor itself is not a capital asset: it is a consumable and you should treat it as such, and be prepared eventually to buy a new one, probably on a longer cycle than you buy a new battery (I think my case, where I wore out a motor before a battery, is an outlier because I'm so careful with the battery, and I knew from the beginning that the sacrificial motor was a learning experience; in fact I expected it to fail much earlier than it did.) Specifically, steel gears instead of plastic will last longer, and you should in your first month or so, or your first summer, check that the motor doesn't get abnormally hot. I haven't fitted the steel gears because I value silence a great deal and I'm not particularly trying to make my motor last extraordinarily long.
Ask if you need to know something more.
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I think the SJS website had a couple of modified eThorns for sale recently. Endorsement enough I wager?
Speaking with a middle aged farmer recently I’m quite accepting of the appeal of ebikes. The farmer said that with his knees the ebike took the sting out of exploring The Lakeland fells, particularly during the winter months when he had more opportunities to get out and ride.
I’d have one although seeing one for £12k recently made me almost break out into full Victor Meldrew mode.
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Thorn do appear to offer conversions to some of their models using the Pendix system. Not cheap and the RST is not mentioned but maybe worth discussing the possible options with them.
https://www.sjscycles.co.uk/ebike/pendix-motor-kit-300w-long-reach-magnet/
Good shout. I'd forgotten the Pendix, it's different to other mid drive motors so maybe it doesn't interfere with the EBB. i did consider one for my Airnimal folder as it doesn't interfere with the fold, I can't remember why I rejected it, I think the costs just got to the point where it made more sense to buy a dedicated E-bike. There were some compromises, particularly that a lot of the control is built into the battery pack, making an additional, or replacement, battery more expensive than with other systems.
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2. I believe that in the UK there is a power limit on the size of motor you can use on the public roads.
The UK has retained the same regulations as the EU, as far as I'm aware there is no proposal to change this. There's also some confusion about where you can use non conforming bikes, it isn't just roads you can't use one, it's any public Right of Way.
Bafang supply a range of motors, those labeled as EN15194, will be the same as those with the same label produced anywhere else in the World. That stipulates 250w as the maximum continuous output, the peak output is likely to be considerably higher, at least 300w, possibly as high as 400w, this is all within the regulations. You can of course de-restrict any, though some manufacturers (Including Bafang) are working to make this harder. If you have an EN15194 and configure it to continually run at a higher power it'll have a fairly short life. Configuring it to offer the same power without the speed cut-off is something different, this is basically what most EU Speed Pedelecs are. Sadly there's never been any EU classification for these, it's been left to nation states, in the UK they are classed as mopeds, so very few bother with them.
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Thanks for your replies.
I'm looking at a SWYTCH system with a restricted speed motor in the front wheel. That way I won't change the excellent dynamics of the RST too much.
I've ridden a Mercian with one of these and to be honest it was just like riding the normal bike until I arrived at a "slight incline" when one felt the assistance kick in.
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Thanks for your replies.
I'm looking at a SWYTCH system with a restricted speed motor in the front wheel. That way I won't change the excellent dynamics of the RST too much.
I've ridden a Mercian with one of these and to be honest it was just like riding the normal bike until I arrived at a "slight incline" when one felt the assistance kick in.
And you get tidy wiring and interchangeable batteries. Good call if it will otherwise suit your needs (handle your weight and shopping, effective rather than claimed battery range), and if you can somehow ascertain how durable the system is.
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I don't yet need to, but my current plan A for electric assistance should it be necessary sometime in the future is to fit a front hub motor to one of my Raven Tour frames. Perhaps with a different fork if I reckon the original isn't strong enough. And after using this relatively simple conversion for some time, probably get a purpose-designed electric bike later on.
Plan B is simply to make more use of my Brompton folders, combined with trains and buses and just cycle shorter distances.
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Thorn do appear to offer conversions to some of their models using the Pendix system. Not cheap and the RST is not mentioned but maybe worth discussing the possible options with them.
https://www.sjscycles.co.uk/ebike/pendix-motor-kit-300w-long-reach-magnet/
The Pendix system requires a square taper BB so if the RST has square taper a Pendix would work.
AFAIK most of the mid motor conversions require removal of the BB bearing and replacement with the e assist. Easier with a square taper than the external bearings on a Mercury for example.
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The Pendix system requires a square taper BB so if the RST has square taper a Pendix would work.
AFAIK most of the mid motor conversions require removal of the BB bearing and replacement with the e assist. Easier with a square taper than the external bearings on a Mercury for example.
I only use ST BB's, including on my Mercury.
The issue with most mid drives is they're a rigid fitting, once fitted it wouldn't be a simple job to alter the relationship between BB and frame, so the EBB becomes unusable. The Pendix is different, it looks like it's all connected to the crank, as far as I can tell, adjusting the EBB also moves the motor with no extra work.
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Just buy a motorcycle or if funds are low - a scooter - seems to be the most intelligent answer. Unless you are religious about bikes after all.
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Just buy a motorcycle or if funds are low - a scooter - seems to be the most intelligent answer. Unless you are religious about bikes after all.
On my recent visit to New Jersey cycling along the Hudson Trail I was frequently passed by all manner of electric, err....... things.
Skateboard for sure. Scooter and bikes, definitely.
My impression was that USA is ahead of UK.
Along side my impression that helmets are worn less, State side.
Wonderful to see a different side of personal transport.
And one thing that was a ball with foot plates either side. Very unusual for me, and very fast.
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On my recent visit to New Jersey cycling along the Hudson Trail I was frequently passed by all manner of electric, err....... things.
Skateboard for sure. Scooter and bikes, definitely.
My impression was that USA is ahead of UK.
On a different road (Path?) certainly, but I'd say despite the speed they're behind Europe rather than ahead.
The European E-bike industry has worked hard to equate assisted bikes with traditional cycling. This is far more obvious in those countries with more of a cycling tradition and usage. The principal is a bike is a bike - it only works if you regulate output so they can mix without one disadvantaging the other.
The US approach has been to create a different class of cycle, without restricting it at a comparable level. In the short term that's a lot more fun for the rider, but is some circumstances it isn't appropriate, already E-bikes are banned on some US cycleways, that's not something we want in the UK.
E-scooters and other E-things are a different matter. They rocketed in popularity while most people were still considering them to be a short lived fad. I think we are in a travel revolution and I don't know what the outcome will be, but I doubt it'll be bike shaped.
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The US approach has been to create a different class of cycle, without restricting it at a comparable level. In the short term that's a lot more fun for the rider, but is some circumstances it isn't appropriate, already E-bikes are banned on some US cycleways, that's not something we want in the UK.
<nods, sadly> This is indeed what I see daily here on the feeder route to the bike paths that go past my house. e-Bikes with virtually unlimited power go scorching by at high speeds and once on the segregated bike paths, do the same. The problem is not the machines themselves -- they look like loads of fun in my eyes -- but the operators who show poor or little judgement and are often not in full control. A lot of these bikes have high-trail geometry and are heavy, so driven at speed around tight corners, they tend to run wide and several have nearly taken out myself and others in such circumstances.
I equate their presence with what I saw in the Netherlands in 2008, after it was made legal to run small motorbikes on the bike paths. While displacement was capped, virtually all were fitted with unmuffled, large expansion chamber exhausts and other mods that allowed higher speeds than the law anticipated. Most of the largely youthful operators figured there was little point in having power and speed without exercising it and so twisted their throttles fully at every opportunity. I spent 5 weeks based in Schiedam, a suburb of Rotterdam, but saw similar in The Hague, Amsterdam and Rotterdam and soon came to value the more rural paths where such mixed use was unknown and the old Dutch upright pushbike was the norm.
E-scooters and other E-things are a different matter. They rocketed in popularity while most people were still considering them to be a short lived fad. I think we are in a travel revolution and I don't know what the outcome will be, but I doubt it'll be bike shaped.
These are HUGE in my area and growing moreso. The variety is remarkable and now we are seeing truly high-speed e-unicycles (EUC). One recently advertised has a top speed of 87mph/140kmh. Here is an example form last year, some faster now...
https://www.youtube.com/watch?v=z-Aiccjwn-w
I pedaled down the River Road on-street path (major arterial at the end of my street) and was pretty satisfied to nearly pace the 35mph/56kmh traffic at 30mph/48kmh on my Fixie when I was passed by one of these EUCs that in turn passed all the cars at nearly twice speed. Kinda hard to watch for 'cos so far beyond the greater traffic mix in terms of speed and maneuverability.
Be safe out there.
Best, Dan.
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Dan,
What fixed gear are you riding at 48km/h? I am impressed.
E scooters. In Victoria and some other Oz states their use is banned in all public areas, roads, shared paths, pavement/sidewalk/footpath. They may be purchased but can only be used on private property.
Of course the Police have plenty of other work to do so there is little enforcement.
There was an early Darwin Award candidate here in Melbourne a week or so ago when an e scooter rider hit a "traffic calming device" aka speed hump and went over the bars, hit his head and carked it.
The exception to the rule is that in the CBD/Downtown area you may hire a severely speed limited e scooter to get around there and they are quite popular. You do see a few outside the area abandoned, presumably because the battery had run down.
Back to the sacrilege topic because my Mercury does not have a square taper bottom bracket I could not fit a mid motor so I purchased a Merida Speeder 100 run out model for AUD 600 instead of RRP AUD 999 and took it to my local ebike conversion shop where I got a Bafang mid motor 250 watt and a 36V 15AH battery installed for a further AUD 2,000.
My first ride last week was 77km using mostly level 1 of 5 and there was still about 30% charge remaining in the battery.
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What fixed gear are you riding at 48km/h? I am impressed.
I was too, when I looked down at my speedometer and the computer logged it as my maximum speed! ;D It is a 38 x 16combo for a 64in gear, so my legs were a-spinning at 160-161RPM. I didn't hold it for more than a couple blocks before returning to my usual and a speed of 36kmh.
I usually prefer a cadence of 110-120, so this was pushing it for me. My hummingbird cadence makes up for my generally low gearing. As an aside, my Fixie is based on a 52 year-old road bike. Still going strong after "rescuing" it for $20. It had sat out in the winter snows of Central Oregon for two years while it failed to sell at successive garage sales. The original owner finally just wanted it "gone" for a minimal price and I was happy to oblige.
I really must stress I have nothing against e-Bikes, only against some operators I've encountered who rode them at speeds too high to be safe for conditions. I've the same complaint about car drivers who speed recklessly and endanger others. It only takes a few bad apples to create an unfortunate impression and regulation. I saw the first official "speed limit" sign has appeared on my local bike path this morning -- 12mph or 19kmh. The vast majority of the e-Bikes I see here are operated safely and well and provide enjoyment and much-needed mobility.
Best, Dan.
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It's fitted and it keeps me cycling.
QED
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It's fitted and it keeps me cycling.
QED
I'll be interested to know what range you get under different conditions. My time will come (but not, I hope, for several more years) and I hope that by then the likes of Swytch will have added regenerative braking.
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So far I've had 30 miles on flat Fenland roads & farm paths on a warm-ish day That was using the lowest assistance setting and averaging a gentle 10 mph. However on a cold day with a few what we call hills in Lincolnshire it dropped to 18 miles before the battery gave up. Mind you the designed battery capacity is for commuting rather than touring or days out. Obviously the range can be extended if you only switch it on when you feel the need or control the motor with a thumb throttle.
On the regenerative braking, various discussions on this. The output of a front hub "dynamo" is about 3 watts and you don't really notice the drag when it's on but if you wanted more I guess you might end up going over the handlebars when it kicked in. It would need software control to gently kick in.
Back emf rules ok as our lecturer would say or have things change in the last 50 years !
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On the regenerative braking, various discussions on this. The output of a front hub "dynamo" is about 3 watts and you don't really notice the drag when it's on but if you wanted more I guess you might end up going over the handlebars when it kicked in. It would need software control to gently kick in.
Thanks for the range feedback. That's worse than I had expected.
I would be using the motor for regeneration as is done on hybrid cars where pushing the brake pedal switches the power system to regeneration (with the mechanical brakes used for stopping or for extra braking power). I would fit sensors on the bike brake levers to do the same thing on a e-bike - pull the brakes a bit for regeneration, pull harder for the mechanical brakes. I recently came across an e-bike where regeneration was triggered by pedalling backwards, so it can be done.
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It's fitted and it keeps me cycling.
QED
Hallelujah!
To me that's the whole point of the e-bike.
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I would be using the motor for regeneration as is done on hybrid cars where pushing the brake pedal switches the power system to regeneration (with the mechanical brakes used for stopping or for extra braking power).
Bicycles simply do not have the weight and momentum (embodied energy) that a motor car has. The benefits of such braking systems would be marginal; you could try to run braking through some generator but the increase to battery charge level is going to be truly minimal. I do not know the data on it, but you can be sure - if it was feasible and effective, it would have been done already.
https://youtu.be/k4Oe4hv4QpI
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Thanks for the link with interesting comments below it. The benefit of regenerative braking will depend on the usage pattern. It will be negligible if cruising on flat or gently undulating terrain but will be significant in conditions where the brakes are used a lot and without regenerative braking the range using the battery will be substantially diminished . I think this can be grouped into two categories: Urban cycling with lots of stop - start; and hilly conditions where there's lot of effort getting up the hills followed by cautious descent down the other side.
The majority of e-bike purchasers are only doing relatively short trips well within the bikes range. I anticipate, however, the demand for regenerative braking will increase as more purchasers find disappointing range for their usage pattern.
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It's fitted and it keeps me cycling.
QED
Congrats, is that the Swytch kit? I don't know anything about them other than the ads, they look to have pretty small batteries, like the Brompton kit, do you know the capacity?
Re regen braking for E-bikes, at current levels of technology its a non starter. It's borderline even on many E-motorbikes, where you don't have the disadvantage of pedaling against the motor, many manufacturers consider that an increase in battery size gives better additional range for the same weight with less complexity and at a lower cost.
I don't know about others, but I spend less time braking when riding a bike than when driving a car, though with the car a lot of that will be engine braking, there's not much genuine freewheeling when driving. I freewheel quite a lot on a bike, without braking, I don't want a charging system slowing that. Maybe someone could work out how much regen you get for a micron of brake pad? My E-bike has done a touch under 10,000 km of urban deliveries, last week I changed the pads for the fist time, the resin type which are supposed to be fast wearing, the front was a little overdue, the rear had some life left. Regen braking in an EV is a different matter, absolutely brilliant, I'm in a car club and one of the cars I use is a BMW I3, with a bit of care you can do 100's of urban miles without touching the brake.
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The benefit of regenerative braking will depend on the usage pattern. It will be negligible if cruising on flat or gently undulating terrain but will be significant in conditions where the brakes are used a lot and without regenerative braking the range using the battery will be substantially diminished .
I think you may have missed the point about the lack of embodied energy, even in hilly terrain on descents, and that regen-braking uses direct-drive, not a freewheel. You WILL be constantly trying to pedal against the friction of the motor. As for use in short/long range, a good friend of mine uses his e-bike for long-distance touring (carrying quite a major load). He gets 2 days riding on tours out of the battery between charges, on 60-80km days. He rides with the power-assist level set to 0 most of the time, and only dials it up to about 3-4 on the 0-9 scale when he gets to steep or long hills. On a true pedelec with auto-throttle and assist only when pedalling.
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I was curious on finding out more in this regenerative braking discussion. I found this article https://www.cyclingnews.com/features/do-electric-bikes-charge-when-you-pedal/ (https://www.cyclingnews.com/features/do-electric-bikes-charge-when-you-pedal/) which explained to me why, although possible, is not terribly efficient on bicycles.
Of course rapidly changing technology and innovation might eventually make this viable, but for now the minor gain from energy recovery vs added weight, cost and minimal range improvement make this hard to justify at this point in time. But in 5-10 years, who knows?
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I was curious on finding out more in this regenerative braking discussion. I found this article https://www.cyclingnews.com/features/do-electric-bikes-charge-when-you-pedal/ (https://www.cyclingnews.com/features/do-electric-bikes-charge-when-you-pedal/) which explained to me why, although possible, is not terribly efficient on bicycles.
That's a good article and includes what I'm thinking about "For example, if an e-bike can help power you up a steep gradient, can it recapture some of that energy on the corresponding descent?" and the comments include "It had a regenerative brake system for recharging the battery, it would engage when you feathered the rear brake lever to trigger it, and was most useful going down steeper hills. It was nice as I had a longer hilly commute around Vancouver BC, and I could keep the battery charged enough for my final hill climb to get home." That's the situation I'm thinking about: Help going up the hills and ability to recapture some of that energy when it's necessary to go down the hills cautiously (ie using the brakes). If braking isn't needed on the descent then there would be no regeneration.
A suitable motor connected to suitable electronics can become a generator. My hybrid car is described as having two motors but in reality it has two motor/generators with the electronics, guided by the use of the accelerator and brake pedals, deciding which way the power flows and how much.
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On a related subject, a friend has just alerted me to this https://www.youtube.com/watch?v=r-Zyp6jX0HM which discusses electrical transmission.