What’s with the watts?

I sent an email to the Bosch help desk asking about optimum cadence. I noticed the motor did not increase its power contribution above 105 revs of the pedals per minute. Generally they recommend a cadence of between 60 and 90 which is fine for me.

I have other queries which I will send to them in due course. One is to do with the maximum watts the motor can deliver. It is stated as 250 watts and I assume this puts a limit on what it can contribute at any particular moment for maximum efficiency for my and the motor’s power output.. Whatever I produce and whatever the percentage increment is theoretically, if the motor’s contribution reaches 250 then it can’t give me any more.

For instance if 40% = 250 then I would have to generate 625 watts myself to get the motor to provide its max 250. If this was possible, then our combined output would be 625+250=875. This would be eco mode.

If 100% (tourist mode) = 250 then I would generate 250 myself, a total of 500 watts.

If 180% (sport mode) = 250 then I would have to generate 139 watts, a total of 399.

If 270% (turbo) = 250 then I would have to generate 92 watts myself, a total of 342 watts.

To get the full 250 watts assistance realistically I could only do this in sport and turbo modes. According to Zwift my FTP is 170 .In addition I’m sure these figures would be complicated due to each mode offering different levels of torque in Nms.

So using real world figures, let’s say I can produce and sustain 120 watts.

In eco mode the increment would be 48 and the combined total 168 watts.
In tourist mode the increment would be another 120 and the combined total 240 watts.
In sport mode the increment would be 216 watts making 336 watts in all.
In turbo mode the increment would be 324 but the motor is not capable of this so would give me the max of 250 and a total of 370 watts. In fact I could produce as little as 92 watts in turbo mode to take the motor up ti its full 250 watts contribution.

 

 

I assume in practice the variable Nms of torque available in each mode would also put a limit on the power available.

It would also be interesting to know how different power figures from me impact on battery life. I assume that in any given mode if my power level is lower and requires less power from the motor, below its max of 250, then there is less demand on the battery. However this may not make much difference to the available range, only the overall average speed.

E-bike: first impressions

I picked it up the new e-bike last Saturday morning and road home from Saltaire via a combination of Hollin Hill, Escholt, Old Hollin Hill and Guisley. I still worked fairly hard but went up the hills at about 10 mph rather than my usual 4 mph on the steeper sections. I assume if I had used a lower gear and gone at my normal slow speed up these hills I would hardly have raised a sweat. As I had hoped, it also meant I got away from junctions and traffic lights quicker and smoother and therefore safer. I’m not able to get out of the saddle for faster acceleration or to get up steep sections of hills because of a knee injury I got many years ago from a motorcycling accident but the electric assist, especially on the sport and turbo modes does the same job for me. According to the control display if I ride it like I have so far (only a hilly 9 mile sample of course) the battery range will be 75 miles. This is better than I expected and means for less demanding terrain when I can stay in eco mode for most of the time I may even be able to get 100 miles, more than enough.

I’ve done two more rides since, a short one to friends Susie and Peter Saturday evening for a BBQ, about 3 miles and arrived fresh as a daisy despite the significant inclines on the way, and to the squash club Monday morning for a regular racketball session. I was very pleased with this as again there were significant hills and using only the eco mode and a touch of tourist mode on a steeper section I arrived in good shape to play.

My bike has the Active Line Plus motor which produces 50 Newton metre torque which I think is something under 2 horse power. The maximum power it an produce is 250 watts and this is used to increase the power I am producing by pedalling. This is provided as a percentage so in eco mode I get a 40% boost, tourist a 100% boost, sport 180% and turbo 270%. The maximum torque provided varies in each mode as well – 35, 40, 45 and 50 respectively. The maximum pedal revs the motor can operate at are 105 per minute which is plenty. However, there is a question about which is the optimum cadence for the motor to produce maximum torque.

So, if I’m producing 100 watts at the pedals (pretty comfortable for me) then in eco mode this is increased to 140 watts, tourist mode 200 watts, sport 280 watts and in turbo mode 370 watts. This is why riding the e-bike makes you feel, in my case, 45 years younger!

E-bike

After several months of research and procrastination I’ve finally bought a power assisted bicycle – an e-bike. Power assisted means that you have to pedal; you can’t ride it like a motorbike or moped. Over 15.5 mph you’re on your own as the motorised assistance ceases at that speed. Above that you ride it like an ordinary pushbike. What sold me on the idea was a ride I did round the 38 mile Isle of Man TT Mountain Circuit a few weeks ago, a ride I wrote about here and which I could not have done on any of my conventional road bikes. I did a fair bit of the ride at over 15.5 mph so unassisted and reached speeds of over 30mph freewheeling down the mountain but made shameless use of the electric motor up the 7 mile mountain climb. It also makes hill starts and setting off quickly and smoothly in traffic much easier and controlled. 

The other thing that prompted me to look into e-bikes was an experience I had a few weeks ago riding with my friend David in the hilly terrain around Settle and Bolton-by-Bowland over the Lancashire border. We only managed 26 miles and David, apart from on the flat and downhill, David was soft pedalling up all the hills or waiting for me. I had to get off on several occasions and walk for a bit to recover my breathing and heart rate on the steeper climbs. Depsite this being a ride long planned and looked forward to I’m sorry to say that on the whole it was not a pleasant experience. To put this in perspective David is 76 and, unlike me, has never given up cycling even doing the odd time trial up unto a year or two ago. Also he is only 11 stone compared with my 14 stone. Combine this with the fact that he is certainly able to produce as much power as me and probably more, the difference in our up hill performance is obvious, especially since I was suffering from the effects of a long term cold. Never-the-less, to match David I would either have to lose another 3 stone or increase my power by about 33% none of which is likely.

It’s the hills that are the killer for me and even though I’m OK one the flat or mildly undulating roads a hilly ride means I run out of energy quite quickly. The e-bike will allow me to enjoy longer leisure rides than I am capable of on my conventional bikes. My limit at the moment seems to be about 35 miles, less on hilly terrain and I’m often knackered when I get home. In fact often the last few miles are hardly pleasurable at all. I’m hoping this can still improve but I will never get back to the sorts or beautiful rides I had in my teens, 20s and 30s. I posted a picture here sometime ago of a certificate I got in the early 1980s for a CTC event covering 240 miles in 24 hours. At 72 those days are long gone. I used to cycle from Leeds to Burnsall in the Yorkshire Dales on Saturday mornings and be back for lunch! Now I can just about do a trip to Bingley 5 Rise lock to the café and back along the canal! With my e-bike 50 mile round trips like Burnsall will be back on the agenda. I will also be able to use the bike to visit friends who live too far away to cycle to and get there without being a sweaty mess and needing a lie down when I arrive. And I will still be getting exercise through cycling but will be in control of just how much effort I want to make rather than this being dictated by the hills and wind. It also means I can wrap up properly against cold and rain as with the power assistance I won’t be marinating in my own juices when the going gets tough.

I can’t think of a downside to this decision for me but time will tell. I’ll let you know what problems I have if any.

Isle of Man TT circuit by e-bike

Last week we went to the Isle of Man with friends and while we were there I hired an e-bike to ride round the TT motorcycle race course, the Mountain circuit. I hired the bike for a day from The Green Wheelers Electric Bike Company at the Sea Terminal at Douglas who I can thoroughly recommend. When I picked up the bike it took about 5 minutes to have everything explained to me. Basically, you ride it like a normal bike. You use the gears as normal – lower gears on hills and at low speed, higher gears on the flat or downhill at higher speeds. The bike I hired had 9 gears I think (I forgot to count them!) and I only had levers on the right handlebar as the bike had a single chain wheel. The electric motor (250 watts) was controlled by a small unit with a display operated by my left hand. There were two big easy to use buttons marked + and – which cycled through the various ‘assistance’ modes. Smaller buttons were to turn the motor on and off and to vary the information displayed – time on the move, current speed, average speed and so on. The display also showed how much of your battery charge you had left and which of the assistance modes you are in.

Most e-bikes in the UK are described as ‘pedelecs’. This means that they don’t go anywhere under motor alone. This would make it a electric motorbike. Apart from freewheeling (when the motor turns off anyway) the bike won’t go anywhere if you’re not pedaling. The motor will assist your pedaling, not replace it. It does this by increasing the power you are producing through the pedals by a percentage. In ‘eco’ mode (in which the battery will last longest) the power you produce is increased by 40%. I can pedal along quite comfortably on a bike producing about 120 watts of power. In eco mode this would be increased to nearly 170 watts without any further effort by me. The other assistance modes are ‘tour’ (100% increase), ‘sport’ (170%) and ‘turbo’ (250%). So using the turbo assist my 120 watts would be increased to 420 watts, the sort of power a top professional cyclist would use climbing an alpine climb!

Obviously the battery life varies with how much assistance you use. When I rode round the Isle of Man TT circuit I used mainly the ‘eco’ assist mode and only used the ‘tour’ mode on the 12 kilometre climb. For this section I averaged about 9 mph and probably pushed myself up to 150 watts or so. Without the assistance I would have worked much harder and probably would have to have stopped a couple of times on the way up. I tried the sport and turbo modes briefly to see what they were like and it reminded me of how I used to ride at the height of my racing career in my 20s! However, I stayed in eco mode most of the time as I wanted a good workout. I rode 45 miles altogether as I took a detour off the circuit at Tynwald to meet friends in Peel for lunch. At the end of the ride I had used about 80% of the battery. It would probably last about 70 miles on eco.

Another thing that helps battery life is that the motor turns off at 15.5 mph (25 kph). On the flat or wind assisted I was bowling along at 17 or so mph. On the long descent of the mountain I was over 30 mph most of the time, touching 40. With a little practice on normal undulating roads you can keep the speed just under the 15.5 mph and ‘surf’ the motor. This makes riding very easy indeed. This has been described as feeling like your dad is riding beside you with his hand on the back of your saddle. Others have said it’s like the hills have been flattened out. For me it was like I was 45 years younger!

The bike I hired was a heavy mountain bike and the technology, motor and battery, have already been superseded. None-the-less it was impressive. There are many excellent off road routes on the Isle of Man for which it would have been ideal. When the day comes for me to buy an e-bike I will probably buy a lighter more road orientated version that would be easier to ride as a conventional bike. If the battery had run out on my hired mountain bike it would have been very hard work to get it home under my own power.

VTTA racing on Zwift

This week a new departure in my virtual racing career. A Zwift group called Sporting Course Time Trial Series run time trials over hilly courses on Zwift. You accumulate points over the series at the end of which a final leader board is constructed. So far the groups have been organised on the basis of FTP but on Thursday they ran their first event using the UK’s Veterans Time Trial Association rules. Veterans are riders 40 years of age or over. For all the standard UK time trial distances (10, 25, 50, 100 miles and so on) each age has a standard time. For instance, for a 10 mile TT a 40 year old has a standard time of 25.59 and for a 71 year old like me it is 29.14 – still marginally over 20 mph! The VTTA web site standards page also has a facility to calculate custom standard times for other distances. The race I took part in was 17.4 kilometres so my standard time was 31.38. I was the oldest rider by 5  years and, apart from a couple of 62 year olds, everyone else was under 60. As you will see from the results below the winner was the only female in the field and I was last.

I was one of only two who didn’t better their standard time. The overall result is calculated on the basis of times achieved relative to the age standard. Compared with Scott who finished one place a head of me, I was 2.27 slower but on age standard I was only 14 seconds slower. I very nearly wasn’t last!

The intention is to run these VTTA style events on a regular basis so I hope to make some progress. I did the same course as a trial and recce on the Wednesday and went round in 34.42 so the race was just on a minute faster. In the process Zwift upgraded my FTP to 164 watts so I obviously made a bit of an effort.

Racing with Zwift

There area number of different types of organised rides you can do on Zwift with a 24 hour calendar of events. So far I’ve done social rides and a few races. Recently they have introduced group training workouts to supplement the menu of different workouts for individual riders. I haven’t tried a group workout yet but will do so in the next few days hopefully.

They are like the individual workouts in that you work through a series of intervals based upon a percentage of your FTP but you are riding in a group that always stays together (assuming you keep pedalling) despite in practice producing different watts that would in the ordinary way mean individuals would be travelling at widely different speeds. Unlike a social ride or a race you can’t get left behind and you can’t escape off the front. The illustration above shows that despite the riders in the group list producing varied watts per kilo but still riding in a compact group.

I have done a few races. My first one was a handicap event where you signed up to race in one of 4 grades, A, B. C or D. I was in the D grade for riders whose watts per kilo are 2.5 or less. My FTP is about 150, maybe a little higher, and my weight is 87 kilos so my watts/kg are 1.7 so as you might imagine I took quite a pasting! THe groups started at 3 minute intervals with the D group setting off first. I got dropped very early, after about 5 minutes and rode alone until first the B group and then the A group came flying by far too fast for me to latch on and get a draft. After about 30 minutes the C group caught me going significantly slower than the B and A group and, if I had not been so knackered,  I think I might have been able to stay with them for a while. In the event I was just about cooked by then, 40 minutes into a 60 minute race, and I blew up and stopped. My big mistake was not realising I had to go absolutely flat out for the first few minutes so as not to get dropped by my D group. I let them go because I knew there was no way I could keep up the speed at the beginning of the race for a full hour but I now know neither could they. After I dropped of I found that after a while the gap between me and them more-or-less stabilised. They still drew away form me but quite gradually and not so fast that, had I still been with them and drafting, I could have lasted much longer with them. Who knows how long but the C group would have caught us or me much further into the race and I may have had a chance of at least finishing and getting a position. I’ll try this race again in due course I think.

Otherwise I’ve done 5 races with The Big Ring handicap events. These are rather different in that everyone starts together but are handicapped by adding or subtracting from their weight depending on their FTP. The idea, I think, is to make everyone have the same watts per kilo so that in practice the same watts produced at anytime in a race, up hill or down dale, will produce the same speed over the ground. This means in theory that the only difference between riders and therefor the race results will depend on how they manage their effort, for instance judicious use of drafting, choosing when to use energy closing gaps and when to conserve it and hope to get a tow across, when to climb at a steady rate and when to make a greater effort to bridge a gap or drop someone drafting you, and so on. And of course, the ability and stomach for suffering!

So far my results have been mixed to put it mildly! My first race I didn’t finish. I got dropped in the ‘neutralise’ ride to the start where the leader’s call of ‘go, go’ go’ started the real race. An ignominious start. My actual weight at the time was 88 and I was riding with a handicap of 78 I think. The problem was mainly not warming up properly and not being mentally prepared to go with the pace even for the roll out. As a result of this the TBR handicapper took pity on me and I found I had a handicap of 61 kg for the next race. Not surprisingly I found I was able to stay with the bunch near the front and finished 3rd. I was with the leaders at the top of Box Hill after a hard chase but had little left for the few miles left to the finish. So, a podium. In fact the next race, with the same handicap, I won! This was in the final sprint which I took by 2 seconds.

This, I’m afraid, was a false dawn for my renewed racing career at the age of 71 and after a 31 year break from road racing. A mistake had been made on my handicap and rather than 61 kg it should have been 88, the same as my real world weight. The next two races were a trip back to reality for me. My third race I finished last just over 4 minutes behind the second to last rider and about 12 minutes behind the winner, someone who I had beaten by two and half minutes the week before! I rode the whole race by myself apart from the first 5 minutes. My fourth race, last Tuesday, once again I finished last, this time over 5 minutes behind the penultimate rider and nearly 15 minutes behind the winner. This sounds worse than last week’s race but in fact there were some signs of improvement. I managed to stay with a small group for about 15 minutes before getting dropped but managed to stay with and get a draft from one other rider. I managed to do a few brief turns on the front but even drafting I was at or above my threshold for most of the time so wasn’t much help. I hung on until the bottom of Box Hill but got dropped by two and a half minutes by the top and struggled to the finish line alone losing a further couple of minutes.

So, from hero to zero in 1 week. It is a little dispiriting but I didn’t start using Zwift with a view to winning races, just to lose weight, get fitter and live longer! Unless my handicap is changed I think I am likely to finish last on a regular basis but it will still be a measure of growing strength and fitness if I can be closer to the riders n front of me and, perhaps, one day, not be last! My next race is tomorrow. Watch this space!

Update 8/11/17. My handicap was reduced from 88 to 76 kilos so I did better in yesterday’s race. I finished last as usual but only 9 minutes behind the winner and 2 and a half minutes behind the second to last rider. I also stayed with the main group for a little longer and lost less time on Box Hill. Progress!

 

Neo update

In the last two posts I mentioned that I had not got the Neo setup quite right as the gears didn’t change very smoothly and one of them, the 4th from bottom gear (i.e. from the largest sprocket) slipped and was unusable. However, I have been riding the bike like this since July and it hasn’t stopped me enjoying riding on Zwift and so up until today have not got round to trying to fix it. This is also partly because it took me so long to fit the cassette in the first place that, since it was ride-able, I was reluctant to spend another 4 hours trying to sort it out. I did discuss this with Woodrups some time ago and the theory was that I had fitted the offending sprocket the wrong way round. I decided to attempt the fix at this stage as recently I had been getting involved in rather more demanding rides on Zwift including some handicap races and I found that the unusable sprocket was frequently the one I needed!

In the event, fixing it today was not too bad. I had indeed fitted the 4th sprocket the wrong way round and when I put the bike back on the trainer this gear now worked fine. Much to my dismay another sprocket had become unusable due to slipping. In this case I spotted straightway that I had put a spacer on the wrong side of it so it was hard pressed up against the next sprocket, thus making 2 of them unusable. This was soon remedied and now all seems well. The whole process took me about an hour so a vast improvement on the 4 hours the original cassette fitting took me.

I have made extensive and regular use of the trainer and Zwift but not had much time to record anything here. I will do so in the near future, including my first experiences of virtual racing. I’ve still be going out in the real world (IRL rides – in real life) while the weather has been good and will continue to do throughout the winter but there is no doubt I will hit next Spring significantly fitter than in the past now I have a smart trainer and Zwift.

Tacx Neo – 5 weeks later

In the 5 weeks I’ve had the Neo I’ve ridden it 27 times. long enough for a detailed reflection on the experience. It’s an expensive bit of kit and, if you pay the full price, can cost you £1300. I did rather better than that but it was still a considerable investment. I bought it for various reasons but on the technical side it is the quietest on the market, it has all the necessary connectivity for use with laptops, smart phones, TVs and, importantly, Zwift (of which more later – it is the deal maker as far as I am concerned) and even has a ‘road feel’ feature so that you feel the cobbles, paving, boardwalks and gravel as you ride over them. This can be disabled if you wish. It is also very accurate in its measurements of cadence, watts, speed and miles as well as how it reacts to gradients – It will measure power at far higher levels than I will ever achieve and accurately simulates gradients up to 25%. How all this adds up to an enthralling experience when riding on Zwift, either alone or in a social or race group, I’ll leave ’til another post.

When I got it home and unpacked it, I found the setting up was very easy with the exception of fitting the sprockets to the freewheel body. It is designed to take either Shimano or Campagnola sprockets, 10 or 11 speed but this complicates the way the sprockets line up with the appropriate spines. I took me nearly 4 hours to get the sprockets on and my Giant Defy Advanced up and running on the trainer. The first problem was getting the sprockets on in the first place. I couldn’t see how they should slide on so I just tried everything until, one at a time, I succeeded in getting them to slip over the splines. But then the sprockets were loose. On reading the instruction again I deduced (it wasn’t very clear) that as I had only 10 sprockets I needed an additional spacer behind the innermost sprocket to make up for the missing twelfth. So it all had to come off and be put back on again. Hence the four hours.

Once the bike was on the trainer things went better. It was very easy to install Zwift on my laptop and the mobile app on my tablet. I didn’t take advantage of the 1 week’s free trial and started to pay the subscription straight away. Right from the start I was hooked by Zwift. I set up the laptop immediately in front of the bike so I can read the screen easily and reach the keyboard for changing the camera view and sending text messages to anyone I’m riding with. I have an open window beside me and a water bottle on the window sill alongside a Bluetooth speaker on which I’m playing a Spotify playlist. I have a heavy duty rubberised mat under the bike to make the trainer even more quiet and collect all the sweat I leak and I hang a towel over the handlebars for frequent mopping downs. I can easily spend an hour riding on this set up whereas on my old turbo rollers I was bored out of my skull withing 15 minutes. And riding with others up hill and down dale,through London and the Surrey hills, or on The Richmond, Virginia, 2015 world championship course, or on the fictional roads and the volcano of Watopia, or undertaking any of the structure training programmes and workouts, brings out a lot more effort than if you’re just pedalling along to a bit of music on a standard set of rollers or a non-networked static bike.

Having said all that, I have had other problems. The most irritating is that the gear changes do not move the chain smoothly through the gears and the 4th sprocket from bottom is unusable as the chain just slips over it. I’ve spoken to the dealer I bought the Neo from and it seem I am by no means the first to have this problem. It sounds like I have put the slipping sprocket on the wrong way round and may have not got the others lined up properly. Having got a couple of tips I will reassemble the block in the next few days and see if I can fix it. In the meantime I will carry on as it is and as I have been for the last 5 weeks.

The other problem was after I upgraded the firmware on the trainer using the Tacx utility app on my Android tablet, Zwift stopped registering my cadence. My on screen avatar just freewheeled everywhere even though my real-life legs were whirling around! I repeated the upgrade process again and immediately all was well. In fact the road feel feature started working too, for the first time.

I’ve ridden with a number of training and social groups on Zwift and loved it all. My FTP (functional threshold power) is currently 167 watts and, given my weight is 89 kilogrammes, my power/weight ration is approximately 1.9 w/kg. This is important as it places me in one of the 4 categories for the purposes of entering appropriate races, training and social rides. The fourth group is D for riders with a w/kg of 1.5 to 2.5. So as you can see, I’m near the bottom of the bottom just about! I have survived a couple of events where the pace was held at between 1.5 and 2.0 w/kg and have just about got to the end of the hour.

So this is where I’m at so far. Another post will report when I get my gear changes sorted out – the shop has offered to do this for me if I can’t manage it – and report on how I’m getting on with Zwift, what the features I love are, and what I’ve learnt about the Zwift platform and virtual riding.

Zwift and smart trainers

For a few months now I’ve been trying to persuade myself to buy a new smart trainer and start riding on Zwift, the internet cycling social platform. So last Tuesday 25th July I bought a Tacx Neo direct drive smart trainer and set it up on the spare bedroom.

It took a while to fit the sprockets from the Giant Defy to the cassette body on the trainer but once I realised it needed an additional spacer (I had 10 sprockets and the body takes 11) all went quite well except I get chain jumping on the 4th largest sprocket, the first separate sprocket after the block of 3 biggest). A smart trainer measures speed (mph), cadence (rpm) and power in watts. When linked to software it will display and record all this data.

I have joined Zwift which gives you a range of virtual locations to ride, at the moment various circuits if different length and terrains on a fictitious island called Watopia, various courses in and around London including the Surrey hills like Box Hill, and the Richmond USA world championship course from 2015. In addition there are a number of training workouts to choose from for everyone from beginners to top athletes.

I have joined three Facebook groups focused on group rides and races on Zwift. The Big Ring, based in Australia, runs a series of weekly races on Mondays and Thursdays. The Monday races are handicap events which in principle puts everyone on a level footing. Most races are for different categories of riders depending on their watts per kilogram measurement. This is calculated by dividing your Functional Threshold Power (FTP) by your weight in kilograms. FTP represents your ability to sustain the highest possible power output over 45 to 60 minutes. Generally speaking the figure used is 95% average power you can achieve going flat out for 20 minutes. Mines about 160 watts at the moment so my watts per kilogram (current weight 94 kg) is 1.7 w/k, not very good. For Zwift races this puts me firmly in the D category for riders under 2.5 w/k. The Big Ring handicap races even everyone up by assigning them a weight to enter into their Zwift profile before the race. Strong light riders have an increased weight and heavy weak riders like me are given a lighter weight to enter. At the moment my race weight is 78 kilograms! The highest is 220 and the lowest 58. My first race will be next monday.

In the meantime I did a steady paced 1 hour ride with another Facebook group, Ride On For Health, or RO4H. This was very steady and it got me used to riding in company, drafting and closing gaps. The illustration below is of me (my avatar is not a good likeness!) leading the group. It’s a good supportive group mainly focused on fitness and health and, where appropriate rehabilitation.  Zwift seems to simulate drafting and the gradients very well and you get a real feel for group riding and the tactics of racing. On this ride I got a bit carried away and around the 40 minute mark another rider, not in our group, came past and I jumped on his wheel gaping my group by about 15 seconds at one point. I dropped back fairly quickly and we all finished together as intended.