Exposure revo

davman

I was having a look at the Exposure Revo dynamo light at The Cycle Show today; one was connected to an Exposure dynamo built into a wheel on a stand, which you could spin.

Spinning the wheel resulted in no output through the light. When I mentioned this to one of the chaps on the stand, when he'd finished nattering about footie to someone, he stated (quite categorically) that you have to be doing at least 10mph before the dynamo starts outputting and that just spinning the wheel as I was wouldn't produce any output through the light.

I currently run a SON dynamo hub powering a Schmidt Edelux front and a Busch & Muller Toplight Line Plus rear. This is, in the main, adequate for my commuting, but I was curious as to how the Exposure compared to the Edeulux (obviously not that realistic, but would give me an idea).

My stating to the guy on the stand that i can spin my front wheel and get an output from the Edelux was met with a shrug and non-interest. He then proceeded to state that the Exposure dynamo was designed by professional bike racers (he was one as well), that it was designed for off-road use, had 1500 lumens and was still in prototype stage. He was adamant I wouldn't be able to generate output just spinning the wheel.

I thought the Revo was for sale, or all the online sellers trying to sell something that isn't actually available yet?

The Exposure website states that it puts out 800 lumens, so who is right, the guy on the stand or Exposure?

My last comment to the guy that the dynamo was wired to the wheel to show people how it is wired and not to produce output was met with a nod of the head. So why bother setting this up in the first place?

My impressions of Exposure after my chat with the guy are that they have designed the Revo for off-road usage (I can understand this if it does output as many lumens as they state it does) only and that on-road usage (which they might get a good amount of business from) isn't really what the Revo was designed for, as their battery powered lights are available for that.

Quite disappointed I couldn't see the Revo in action and be able to make some sort of comparison with my current set-up.

desweller

I would have thought it would be pretty easy to drop below 10mph during a MTB race. Seems like a very high threshold.

I reckon it wasn't a working model.

robdeanhove

Not sure who you were talking to, but you definitely do NOT need to do 10mph to get the Revo to work!

I use mine commuting (off road and on road) to work every day, on mid week thrashes in the woods with my mates where there are some long slow climbs we talk up, and some very muddy, twisty sections of prolonged low-ish speed and it copes fine. I've also been touring on it and done 800miles of bikepacking racing when, on some days, I was so tired I was reduced to a slow crawling speed for hours on end. The Revo has been flawless through all of this and I've not used a battery light for months! My road bike and MTB now have dynamos fitted, and they're staying :-)

You can see my Revo and dynamo setup here: CLICKY LINK

diy

Really don't get why they are using XPG R5s in this it makes no sense. They'd get 20% more output using XM-L U2s. (cost about the same)

Also why only 800 Lumen, sounds like each LED is being driven at 0.5A Better IMO to have gone with fewer LEDs and ran at higher amps. I don't know how much a hub produces but I reckon you need about 10-12w of power to get 800 Lumen

Not really enough for night MTB unless you are riding with others running equally under powered lights.

robdeanhove

diy wrote:

Really don't get why they are using XPG R5s in this it makes no sense. They'd get 20% more output using XM-L U2s. (cost about the same)

Also why only 800 Lumen, sounds like each LED is being driven at 0.5A Better IMO to have gone with fewer LEDs and ran at higher amps. I don't know how much a hub produces but I reckon you need about 10-12w of power to get 800 Lumen

Not really enough for night MTB unless you are riding with others running equally under powered lights.

Have you tried one? One company's 800lumen light is not the same as another's. Mine is way, way brighter than the other "800lumen" and "1000lumen" XML lights that my friends have bought from DX, MagicShine etc.

To my understanding, and consistent with my experience, XM-Ls have a larger LED die than and XP-G, requiring a larger cavity in the centre of the optic. For the same quoted light output therefore, and XP-G will give a superior beam pattern to an XM-L.

It's also worth noting that, while driving fewer LEDs harder will be cheaper, the light will be less efficient plus get hotter, reducing the real (if not the theoretical maximum) light output. Driving 4 LEDs at 0.5A will produce considerably more light that driving a single XM-L at 2.0A, the output of the XM-L will be further reduced by the increased temperature of the higher power density, if heatsinking is comparable between the lights.

It's also necessary to know that a dynamo hub is a constant current device, producing roughly 0.5A (or a little more with a clever circuit), so considerable additional complexity and inefficiency will be introduced by boosting the current. Plus, noting the above, running more LEDs more gently is a more efficient use of the power.

My Revo competes very well with, and stands toe to toe with my friends MaXx-D lights, and beats the quoted "1000lumen" XM-L lights in my riding group. I suggest you try one, or at least see one in action, before you dismiss it so quickly without even all the information to hand you'd need to assess it. I have a 6-Pack battery light and haven't used it for months!

In the above comments I have ignored the fact that the Revo is smaller and lighter (including the hub) than a comparable battery system, never needs to be turned down to preserve burn time and never needs charging.

I'm sure dynamos are not for everyone, yes there are drawbacks too, you need a dynamo hub wheel for one, but a dynamo light is definitely a real and viable alternative option to a battery light worthy of consideration

de_sisti

Could the REVO work with a SON hub?

robdeanhove

De Sisti wrote:

Could the REVO work with a SON hub?

Yes, the revo will work with the hub supplied by Exposure, a SON hub, and SP hub and any Shimano hub too. Most 3W dynamo hub outputs are pretty standard, the only difference being reduced low speed (and you have to be going pretty slow to experience it) light output for the super light hubs, quoted at 2.4W (or 20" wheel) where weight is reduced by reducing the number of poles.

Note: Hun output of 2.4W or 3W is when connected to a halogen lamp, this does not apply to an LED lamp, where the max power is controlled by the light itself, and can be greater if the light demands it. i.e. you can get much more than 3W of light!

de_sisti

Do you think your dyno hub/light set-up is considerably better than, a SON combo with
Exposure/Edulux or B & M Cyo lights?

robdeanhove

De Sisti wrote:

Do you think your dyno hub/light set-up is considerably better than, a SON combo with
Exposure/Edulux or B & M Cyo lights?

That's a two part question
1- Light
2- Hub

I'm very happy my Revo light is brighter and, more importantly for me, has a far, far superior standlight than both the Edelux and Cyo lights. It's also a better light for me than the E3 Triple. I have previously owned an E3 triple and a B&M light, so I am able to make a direct comparison.

The hub, well the SP is marginally lighter than the SON, and depending on whose efficiency numbers you read, each is better than the other, but I doubt anyone could actually tell the difference. For me, the lower part count and internal solution of the SP makes it a more attractive hub and a concept that lends itself to increased durability. I also love the fact it's almost 1/3 of the price! The SP internals are what Exposure have chosen for the hub they offer with their light, the same is true of Supernova. This tells a powerful story for me.

Does that help?

de_sisti

Yes it does. My set-up is a SON hub, Supernova E3 dyanamo light and an Exposure Maxx D front light.
On the rear I use a Dinotte 400L, Supernova dynamo rear light and Smart 1/2 watt. For me it's plenty bright.

Bordersroadie

This is one of the most informative and objective gear threads I've read in a while. I'm fascinated by the dynamo option as I do a lot of night riding. I use an Exposure Toro.

Does the Revo have a "dip beam" ie different power/brightness levels like the other Exposure lights?

Can you "feel" the dymano working on the front hub? I mean, is there perceptible drag or the "ratcheting" feeling that I've read about with dynamo systems, where the rotation of the wheel has to cross several magnetic connections? I'm not a technical expert as you can see. . .

de_sisti

With the Schmidt SON hub, you can feel the magnets when you spin the wheel freely (if the light is switched on).
However, imo, when spinning the wheel with the light switched off, it's hardly noticeable.

When riding with Schmidt SON hub and the front dynamo light switched on, I don't notice any drag and I'd challenge
anyone to say they can honestly say they feel it.

robdeanhove

Bordersroadie wrote:

This is one of the most informative and objective gear threads I've read in a while. I'm fascinated by the dynamo option as I do a lot of night riding. I use an Exposure Toro.

Does the Revo have a "dip beam" ie different power/brightness levels like the other Exposure lights?

Can you "feel" the dymano working on the front hub? I mean, is there perceptible drag or the "ratcheting" feeling that I've read about with dynamo systems, where the rotation of the wheel has to cross several magnetic connections? I'm not a technical expert as you can see. . .

No, the Exposure Revo does not have a "dip" beam, but neither does any other dynamo light that I am aware of. The drag is so minimal, there is no benefit and, unlike battery lights, there's no need to turn the brightness down to increase burn time

On my road/winter/commuter bike I have the dynamo pointing slightly more downward than on my MTB so as not to dazzle oncoming traffic with the centre of the beam.

You can not "feel" the dynamo through the hub in use. When turning a dynamo axle slowly by hand you can feel the resistance of each individual pole (but this resistance is then an acceleration as the pole is passed, making the net less almost zero), but this can not be felt when turning a built up wheel, in either frame or wheel jig, let alone in the bars with the light on.

desweller

When I rebuilt my bike with a dynamo hub I also went from skinny lightweight rims to really wide, heavy Rigidas for long life, amongst other things; the bike is a lot slower (between 20% and 40% depending on distance and terrain) but I can't distinguish between the dynamo and the other mods.

I can definitely feel the lumpiness of the hub (as a distinct vibration) through the handlebars at low speeds though. I'm using a Shimano model with an Edelux front light and Phillips Saferide rear light. I couldn't justify the price premium of the SON hub, beautifully made though it undoubtedly is. Popularity of this stuff seems to be on the increase though, so I expect the technology has moved on quite a bit from when I made my choices 2 years ago.

There's quite a range in price for the good lights. My Edelux cost £120 and does not seem to have come down in price much; the E3 triple is what, £140? And the Exposure is circa £200, so you'd hope it would blow the other two out of the water!

It'd be nice to see a beam pattern test covering these three lights. I love my Edelux. It's designed to cut the top of the beam off, so you can set it to give good distance without dazzling oncoming vehicles and riders. Very nice indeed.

robdeanhove

DesWeller wrote:

When I rebuilt my bike with a dynamo hub I also went from skinny lightweight rims to really wide, heavy Rigidas for long life, amongst other things; the bike is a lot slower (between 20% and 40% depending on distance and terrain) but I can't distinguish between the dynamo and the other mods.

I can definitely feel the lumpiness of the hub (as a distinct vibration) through the handlebars at low speeds though. I'm using a Shimano model with an Edelux front light and Phillips Saferide rear light. I couldn't justify the price premium of the SON hub, beautifully made though it undoubtedly is. Popularity of this stuff seems to be on the increase though, so I expect the technology has moved on quite a bit from when I made my choices 2 years ago.

Having owned a few hubs and lights, I suspect by far the biggest difference, and what drives the "lumpiness" is more the hub than the light. The latest lightweight, super efficient dynamos (SON & SP) are a marked improvement, as well as being half the weight and more efficient, on a cheaper (although undoubtedly robust) Shimano offering. I'm not sure how much the latest lights might helps things too

diy

@robdeanhove - I'm not knocking the Revo, it certainly seems better than most Exposure lights which are generally very bad value for money. But you haven't convinced me on the wisdom of 4 XP-Gs. The XM-L and XP-G scale fairly linearly up to 700mA, that is because they are designed to put optimum output out at 700mA (which the base test current).
However, what you might gain in lower amp efficiency you drop in having additional driving/buck circuits.

That aside, the real issue is Lumen per watt, and the XM-L performs quite a bit better than the XP-G on that front:


I suspect also your riding group don't understand the difference between an LED which can produce 1K lumen at 3A (assuming its a U2) and the actual output for the current.

robdeanhove

diy wrote:

@robdeanhove - I'm not knocking the Revo, it certainly seems better than most Exposure lights which are generally very bad value for money. But you haven't convinced me on the wisdom of 4 XP-Gs. The XM-L and XP-G scale fairly linearly up to 700mA, that is because they are designed to put optimum output out at 700mA (which the base test current).
However, what you might gain in lower amp efficiency you drop in having additional driving/buck circuits.

There's two issues raised there
(1) Running a low number of LEDs hard or more LEDs more gently
(2) XM-L vs. XP-G

@diy

For (1), I agree with you that, all things being equal, 1-3 XM-Ls run harder is a more compelling option than a multiple XP-G solution. Certainly, for a battery light, an XM-L is the way to go as the driver loss is the same however you drive things. However, for the maximum efficiency and, crucially, for massively improved low speed light, you're far better running a dynamo at 500mA. Boosting the current loses you a small voltage (approx 1V) and crucially this increases the speed at which the light output becomes good and bright. Therefore, for an LED where you would turn the current up on a battery light, you stick to the ~500mA per LED and increase brightness by adding more LEDs in series (and some clever circuitry) for a dynamo light. I have been designing my own dynamo circuits for several years and, with lots of prototypes and back to back testing, this is a pretty clear strategy with the components I am able to find on the market today. This may change with more efficient components & circuits in the future.

Considering (2) At this 500mA output, an XP-G is only a little worse than an XM-L (the precentage difference is greater at higher powers), what you gain in XM-L theoretical light output you lose in optic effectiveness due to the larger LED die. In battery light the far greater light output of an XM-L makes it the best option, in a multi-LED low output setup, the better light "quality" of the compact die from the XP-G, I suspect has made Exposure, who know what thet're doing, select the XP-G, for a better, more usable light output light, ignoring the quoted, theoretical numbers and going with what actually works out on the trail.

I think I understand your concern and, for a battery light, I totally agree with you (as do Exposure who use XM-L LEDs in their latest Reflex light) but fir a dynamo light I think some of the same assumptions do not apply and the compromises are different.

The one thing I hope we agree on is that the Revo is a great little product (no matter what LEDs they used!)

Does that make sense

robdeanhove

diy wrote:

@robdeanhove - I'm not knocking the Revo, it certainly seems better than most Exposure lights which are generally very bad value for money. But you haven't convinced me on the wisdom of 4 XP-Gs. The XM-L and XP-G scale fairly linearly up to 700mA, that is because they are designed to put optimum output out at 700mA (which the base test current).
However, what you might gain in lower amp efficiency you drop in having additional driving/buck circuits.

There's two issues raised there
(1) Running a low number of LEDs hard or more LEDs more gently
(2) XM-L vs. XP-G

@diy

For (1), I agree with you that, all things being equal, 1-3 XM-Ls run harder is a more compelling option than a multiple XP-G solution. Certainly, for a battery light, an XM-L is the way to go as the driver loss is the same however you drive things. However, for the maximum efficiency and, crucially, for massively improved low speed light, you're far better running a dynamo at 500mA. Boosting the current loses you a small voltage (approx 1V) and crucially this increases the speed at which the light output becomes good and bright. Therefore, for an LED where you would turn the current up on a battery light, you stick to the ~500mA per LED and increase brightness by adding more LEDs in series (and some clever circuitry) for a dynamo light. I have been designing my own dynamo circuits for several years and, with lots of prototypes and back to back testing, this is a pretty clear strategy with the components I am able to find on the market today. This may change with more efficient components & circuits in the future.

Considering (2) At this 500mA output, an XP-G is only a little worse than an XM-L (the precentage difference is greater at higher powers), what you gain in XM-L theoretical light output you lose in optic effectiveness due to the larger LED die. In battery light the far greater light output of an XM-L makes it the best option, in a multi-LED low output setup, the better light "quality" of the compact die from the XP-G, I suspect has made Exposure, who know what thet're doing, select the XP-G, for a better, more usable light output light, ignoring the quoted, theoretical numbers and going with what actually works out on the trail.

I think I understand your concern and, for a battery light, I totally agree with you (as do Exposure who use XM-L LEDs in their latest Reflex light) but fir a dynamo light I think some of the same assumptions do not apply and the compromises are different.

The one thing I hope we agree on is that the Revo is a great little product (no matter what LEDs they used!)

Does that make sense

Qwerty Uiop

Any ideas whether the hub bearings are user replaceable? Cup and cones or sealed? Just wondering whether it would be suitable for extended tours.

desweller

Qwerty Uiop wrote:

Any ideas whether the hub bearings are user replaceable? Cup and cones or sealed? Just wondering whether it would be suitable for extended tours.

Which hub do you mean?

I haven't tried to work on the bearings in my Shimano hub; they are conventional cup-and-cone, but apparently the fragility of the wiring that connects the alternator to the outside world makes them a bit of a challenge.

Qwerty Uiop

Apologies. I mean the Revo hub.

robdeanhove

Qwerty Uiop wrote:

Any ideas whether the hub bearings are user replaceable? Cup and cones or sealed? Just wondering whether it would be suitable for extended tours.

The bearings are sealed cartridge bearings, but I understand that a lot of effort has gone into understanding how to get maximum durability and making sure durable bearings are used.

My MTB hub has raced well over 1000miles off road, bikepacking with luggage as well as a bunch of miles training and just riding around, and is still going strong. The road hub (I have one of each) is similarly as good as new, after about 18months of regular commuting use and has done a couple of short-ish tours too.

I don't believe the bearings are officially user replaceable, nor are they officially user replaceable in anyone's dynamo hub, but SP do offer a free bearing replacement service.

dawebbo

I have a sp pd8 with a velocity a23 rim on my training bike. I can't feel the difference in drag, but I ride with a power meter so I can observe the impact afterwards.
I'm using it with a B&M cyo as it's only used on the road, so the beam cut off means I get more light actually on the road rather than flood and don't dazzle the fk out of people coming the opposite way.