De-restricting a cheap kit

[jerrysimon]

I think Cytronex only sell parts to registered owners of their bikes.

Regards

Jerry

 

[peasjam]

I commute on a racer and average about 17mph (7.6m in 24-25mins). There aren't any bad hills and I enjoy pedalling as hard as possible. My only excuse for an ebike kit would be if it gave me a slightly higher top speed.

So how easy is it to de-restrict a cheap kit?

I'd like a lightweight kit so would a 250w give me an extra mph or two?

If this question has been done to death can someone give me a link.

I was in exactly the same situation as you (although on a decent hybrid with a slightly lower av. speed).
I'm happy to peddle hard but wanted a quicker commute for the 19mile round trip, clearly the 15mph kits give nothing in this situation.
I did a kit build, converting my Cannondale Bad Boy 8 with a front wheel 500W 48v BPM motor. I have a 48v 16Ah battery back in a rucksack. I've done the first run this morning and averaged 23mph, top of 28.6
My best none-powered average was 18.6, worst 15.3 (tail/head winds). It seems to me this kind of thing is what you might be after.
Cost for build was $860, plus a lot of messing around as it turned out one of the battery cells was dead.

 

[Scottyf]

Have you actually fitted any torque arm's to that front kit?
And what controller are you using with that?

 

[peasjam]

Have you actually fitted any torque arm's to that front kit?
And what controller are you using with that?

It's the 500w 12mosfet universal controller from BMSBattery.
I've got a home made arm just on one side at the moment of the pipe-clip variety. I'd seen one on here that mounted to the front pannier eye, but thought a bolt small enough to fit would shear easily. The drop outs are 7mm in themselves so I'm not too worried.

 

[jbond]

I was in exactly the same situation as you (although on a decent hybrid with a slightly lower av. speed).
I'm happy to peddle hard but wanted a quicker commute for the 19mile round trip, clearly the 15mph kits give nothing in this situation.
I did a kit build, converting my Cannondale Bad Boy 8 with a front wheel 500W 48v BPM motor. I have a 48v 16Ah battery back in a rucksack. I've done the first run this morning and averaged 23mph, top of 28.6
My best none-powered average was 18.6, worst 15.3 (tail/head winds). It seems to me this kind of thing is what you might be after.
Cost for build was $860, plus a lot of messing around as it turned out one of the battery cells was dead.

What's your lowest speed on the trip when unpowered? If it's less than 15mph, then a low powered setup is still of value. It will still push up the average speed.

Re the BPM setup. There's somebody here with a BPM kit sourced from Cellman on ES. It's a 36v small wheel wind in a big rim running at 48v, a lightly customised controller, A123 16s4p pack. By all accounts it's a bit of a monster; lots of top speed AND lots of acceleration. And we're back into creating something between a Bicycle and a Moped that really ought to be licensed as a moped.

There's another approach in here that's light weight and stealthy. Like the BPM just described, but take a typical 250w motor with a small rim motor in a big rim and/or run at 48v instead of 36v. Use a controller of about 25A limit with A123 batteries. And then try not to use it so you can carry a small battery pack but still get enough range. The extra voltage and/or the high rpm motor keeps the motor adding assist to a higher speed. The extra current setting on the controller and A123 batteries make up for the loss of torque at lower speeds. You might get assist till 25mph, but the motor won't be able to do 25mph on it's own.

 

[peasjam]

What's your lowest speed on the trip when unpowered? If it's less than 15mph, then a low powered setup is still of value. It will still push up the average speed.

That's a fair point, but you need a good distance to make meaningful gains if you're only getting marginal speed increases for some of the time.
Depending on wind conditions, my quickest (un powered) run barely dipped under 15mph at all and my slowest probably around 30-40% of the time to around 13mph.
So a 15mph capable kit in good conditions (neutral or tail wind) has no benefit, on the worst I've yet had it would get me home approx 2-3 mins quicker over a none-powered ride. It's a lot of messing around for 2 minutes to be honest...
I guess terrain type is another major factor; I'm in Cambridge which is flat so my lowest sustained speed is nothing like that of someone who commutes in a hilly area. This makes the value of a 15mph kit significantly lower to me than someone of equal fitness/ability in a hilly area.

One thing I've learnt is that there is no universally great kit or e-bike. I'm happy with my set up, but I totally accept it's not for everyone either conceptually or in practice.

 

[Scottyf]

I use mine for when I can't be bothered to ride. Doing 5 days a week when your going out or been on the pop the night before is a hassle.

I don't want to compromise on my social outings by thinking I need to ok to ride the next morning ;-)

Spoken like a true booze hound!

 

[jbond]

I think you're pointing up a personal issue I have with the market (and the laws). There's not really an E-Bike solution for the enthusiastic bicyclist. You can get a pretty trick bicycle for £500 but to get the same level of performance and components from an E-Bike you need to spend £2000. When you do, it still doesn't provide any assist above 15mph when you spend most of your time above 15mph just peddling. I'm not necessarily talking about something that will do 25mph on the flat on it's own, but something that will go on providing assist up to 25 and doesn't impact the performance of the bare bicycle.

Apart from the generally low quality of components on low and mid range bicycles the big problems are weight and drag from the motor. An extra 10Kg radically changes the feel of the bike. Even though drag can be quite small, it's still noticeable compared with really free running hubs and cassettes.

I've been following this thread on ES with great interest.
Endless-sphere.com &bull; View topic - Commuter Booster - <1kg Friction Drive
Adrian_sm hasn't quite got there yet, mainly due to problems with the control circuits, but that's potentially a beautiful, ultra lightweight, ultra low drag solution to putting assist on a road only racer or hybrid.

 

[peasjam]

I've been following this thread on ES with great interest.
Endless-sphere.com &bull; View topic - Commuter Booster - <1kg Friction Drive
Adrian_sm hasn't quite got there yet, mainly due to problems with the control circuits, but that's potentially a beautiful, ultra lightweight, ultra low drag solution to putting assist on a road only racer or hybrid.

Wow. That is really quite something!

 

[lemmy]

but something that will go on providing assist up to 25 and doesn't impact the performance of the bare bicycle.

I don't know what you've been smoking but can I have some?

In the meantime, I'd like an upgrade to my 175cc trail bike so that it'll do 180mph but not add any weight or compromise the cross country performance

 

[flecc]

In the meantime, I'd like an upgrade to my 175cc trail bike so that it'll do 180mph but not add any weight or compromise the cross country performance

Nitro?..............

 

[jbond]

I don't know what you've been smoking but can I have some?
In the meantime, I'd like an upgrade to my 175cc trail bike so that it'll do 180mph but not add any weight or compromise the cross country performance

Right. Perhaps I exaggerate and should have said "impact the performance too much". My BPM has a measured no load speed of 24mph. So a no load rpm of 25mph out of one of the tiny motors either by using a high rpm wind and/or 48v instead of 36 doesn't feel unreasonable. It should be possible to put together a workable system with this that weighs under 5Kg with all the battery weight low down, maybe even 4kg. Now it's not going to do 25 on it's own. It might not even do 20 on it's own. And it won't have a huge range or huge hill climbing ability. But it still should be providing some real and worthwhile assist that doesn't tail off at an annoyingly low top speed.