K62 – Times Two

The Ego Scooter with it’s chunkier K-62s, front and rear

Last week, having replaced the front tyre with a new Continental K-62, I was given a nasty reminder of the fact that – as much of an improvement this was – the rear wheel was still ready to brutally betray me at the drop of a hat.

My first experience of the remarkable crappiness of cheap, chinese-made tyres came in 1996, when my VFR400 threw me off and went sliding down a (mercifully slow-moving) stretch of the M4 on my way to work one rainy morning. With that in mind – and having already had one scare with the Ego’s former front tyre – I was still taking things easy as I negotiated a wet and windy evening journey to the B&Q just a short hop across town. I was therefore alarmed and infuriated when the rear wheel hit a patch of something-or-other, and slid alarmingly at the cusp of a turn into a side-road that led me back home. The offending something-or-other turned out to be two manhole-covers, one in front of the other, and cleverly positioned on the exact arc that any two-wheeled vehicle would be liable to take as it negotiated this bend. I hadn’t seen it in coming, and it was a harsh reminder that I would never be able to use this bike with any real confidence while it had such sub-standard rubbish performing the vital role of keeping it upright and firmly attached to the road.

By coincidence this came just a couple of hours after I returned home to find a “You Were Out” card from the delivery firm charged with getting my second K-62 to me, but it firmed my resolve to put the thing on as soon as I could to complete the job.

The next day I was ready and waiting when the tyre was re-delivered, and wasted little time in removing the rear wheel and taking it over to my local bike shop, where the wheel’s odd-looking, trailing cable proved something of a novelty to the staff. It was duly fitted for the usual tenner, and I put the bike back together again the same day.

The chunkier tyres, I think, look great, and make the bike seem a bit more grown-up. I’ve always found something faintly ridiculous about vehicles with disproportionately small-looking wheels, and the extra 35mm , or about 1½” that the bigger tyres add to the bike’s height are more than welcome as the bike’s now in better proportion to my own (6 foot, 14-stone) frame. The tyre is also about 15mm wider, all the better to make the most of the quality tread.

An incidental bi-product of the added height is that it sits quite a bit lower on its stand than it did before, but this also introduces an added bonus: Whereas before it seemed to require a bone-crunching amount of force with my foot to lever the stand into position, the new angle of attack that the stand gets allows it to smoothly and easily lock into position.

Ground clearance on its stand is drastically diminished, now barely 15mm or so clear, rather than the three or so inches it had before.

This means, of course, being very careful testing the motor with the bike on its stand, as any slight tip to the rear could send it rocketing off forward.

The Proof of The Pudding…

But looks aside, the question obviously is how the bike handles with both of these tyres in place. It had been raining all day and I wasn’t particularly keen on the prospect of going out in this weather, but the continual drizzle and the wet and puddle-strewn roads really were the perfect testing ground.

The roads were pretty empty so I took it for a good long spin, gently pushing its limits to see if it showed any sign of the twitchiness that it had had before. As I went through a succession of traffic lights, I took to braking harder and harder, to see what it would take to cause the bike to lose traction, but I was delighted to see that no amount of abusing the brakes seemed to even remotely unsettle the bike. And even when I eventually jammed both brakes on pretty damned hard, the bike remained solidly locked to the tarmac – the only consequence was a loud squeal of protest from the front calipers.

I got the distinct feeling – in wet conditions as well as dry – that in a fight between the brakes and the tyres, the tyres were going to win hands down, and that I was more likely to be flung over the handlebars than to put this bike into a skid in anything but the most treacherous road conditions.

So all in all, I’m pretty happy with the results, and feel far more confident flinging the bike around. I’ve not leaned too far over on bends just yet, as this is one envelope that is best pushed very, very gently. But so far so good…

Speed and Acceleration

One obvious consequence of the rear tyre being 10% wider (both diameter and thickness-wise) is that the bike will go proportionately further per turn of the motor. I predicted that I would therefore get a slightly higher top speed, but slightly reduced acceleration. I was however, completely unsure about how this would impact on the soft-start, as I was clueless as to how the controller/motor decides how to feed the reduced power to the motor on ‘take-off’.

On my inaugural run with the new tyre – even in the wet – I felt confident enough to welly it up on the straight, on roads where I was familiar with the top speed I would typically get. When I changed the front tyre – if you recall – the speedometer suddenly became (again because of the new distance-per-cycle) noticably less flattering in its estimation of my speed, and it seemed much harder to get near the venerated 40mph mark.

But with the new rear tyre, I was definitely reaching the 40 mark a little easier than before, and with some experimenting decided that I was getting maybe 2mph (clock-speed) more than I had before. I also noticed that – as predicted – the acceleration was just a little bit soggier than it had been. The soft-start, though, I’m happy to say, appeared to be completely unaffected. Pulling away felt no different than it had before.

The overall effect then, has only been ever-so-slight, so slight that I did question if I was simply fulfilling my own prophecy. With the benefit of hindsight I would have done a more rigid satnav-based benchmark along a set stretch of road to test this on a before-and-after basis, but there are so many factors affecting performance that it’s pretty hard to control for everything. The presence or absence of my backbox, the charge level of the batteries, the amount of air in the tyres and the prevailing weather can all push things either way.

One thing I can say for certain though is that the tyres fit fine, grip well, and don’t upset the apple-cart in any way that I can tell. In my opinion it’s well worth replacing the tyres simply because the one’s that usually come with the bike just aren’t up to the job of hauling around 32Kg (or 48Kg with the upgrade) worth of batteries. £53 is a small price to pay to make sure that what is arguably the most important part of a bike does a good job and keeps you out of danger.

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9 Responses to K62 – Times Two

  1. hohisilver says:

    But what about the effects on acceleration/top speed? Or did you not have the nerve to test them in the wet? 😉

  2. zenid10 says:

    Gah! I knew I’d forgotten something! Bear with me while I stick in an extra paragraph or so about this!

  3. hohisilver says:

    Thanks! Looking forward to getting my K62s fitted to see how they are with my EB2 controller, although that’s a few weeks away yet as although they’re on order I won’t be visiting the fitter till the beginning of November (for reasons too boring to go into) 🙂

  4. Andy Hunt says:

    Hi Paul, the blog’s looking great, so interesting and informative. Almost makes me want to get one!! I’ve got my pushbike back on the road recently, I’ve discovered that my maximum human-powered range is about 22 miles at the moment!!

    • zenid10 says:

      Hi Andy,

      Great to hear from you again! If you’re genuinely interested in the Ego Scooter, UK Eco Scooters are doing a really good deal on some new, ex-display models for an amazing £450! It’s the new model with the uprated 2000W motor (rather than the existing 1400W one). I was tempted to get one myself just to transplant the motor as part of an upgrade.
      http://electricmotoring.forumup.co.uk/viewtopic.php?t=361&mforum=electricmotoring

      If you’re interested, it’s probably best to sign up to that forum and contact the guy (Paul) from there, as I think it’s a ‘special offer’ to forum members.

      As for your push-biking, yes, I did read up on some of your rural cycling trips on your blog (beautiful pictures, BTW!). It reminded me – conversely – that maybe I should get a push-bike too, just to get some proper exercise, as it’s a great way of staying in shape in a non-contrived way (unlike the gymn).

      Would be great to see you again, some time. You’re always welcome to come and see my nice little flat, and I’d be happy to drop up to see how you and ‘the wife’ 😉 are doing, and swap notes on energy-efficient living.

  5. Ryan bennett says:

    Do i need different size tyres for front and back? I need to get both front and back sizes if you know them thanks! Also amazing blog! Love it!

    • zenid10 says:

      Thanks! The rims are the same size front and back (10″), what tyres you put on is entirely up to you. K-62s (3.5″) are good ones to have in place of the usually bad ones that come with the bike (which are usually 3.0″). The “Big bopper”, though (4.2″), is quite tall and is only suitable if you have a decent controller with the power to deal with the extra anglular force needed to turn the wheel. I don’t know much about the issues regarding mixing tyres, but would guess it’s probably better to keep them the same type, especially when it comes to tyre tread.

  6. kevin says:

    I m rather new to electric bikes but i also must say that your Bloggs
    are fantastic, so much information is available regarding almost all problems encountered with electric bikes, it must take alot of time and effort to do this so I would personnally like to thank you as it has helped me understand the quirks and problems that most electric bikes have. I am currently even after only haveing doing five trips on my Eco planning my 60 volt convertion and cant wait to see the differance be it small and who knows 72v will follow

    Kevin

    • zenid10 says:

      Hi Kevin, Thanks for your kind words! I’m glad you enjoy the blog, It’s nice to know that managed to put together something that’s of use to other electric bike enthusiasts. Good luck with the conversion(s) and be sure to ask here or on Electric Motoring Forum if you need any pointers.

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