Efficiency

Hi Everyone,

I'm riding around on Continental sport contact 26x1.6 Tyres. Pumped to 90 psi they are rather uncomfortable, but brilliant to pedal.

I wanted to go for a spin today and wasn't bothered to pedal so I let half the air out. It was so much comfortable on the road at speed.

On the 6.2 mile spin that I go to test, my consumption went up from 48 wh/mi to 55!

So out of the 510 watt hrs of battery I loose about 1.5 miles from the loss of 40-45 psi!

I was thinking of going with 26x2.3 nobly tyres for the winter, I probably won't be doing much cycling for the winter, but that's making me think twice!

The other test I did at the weekend was at 20 mph all the time no pedalling and got 25 miles from the 500 wh/hr pack. With wheels pumped to 90 psi.

It's amazing the amount of power required to go from 20 mph to 35-40!

Hey,

I fully believe the difference in effieciency. I used to run on 26x2.1 knobbly tyres pumped up to 60PSI, but last month i upgraded to 26x1.9 schwalbe land cruiser tyres with low rolling resistance center tread pumped up to same 60PSI. My average consumption on the 10 mile trip i do every saturday went from 32wh/mile down to 26wh/mile. I also find it much easier to pedal unpowered above 10MPH than i did on the knobblies. Ramains to be seen how the tyres handle in the typical winter riding conditions but grip seems good in wet so far. If we get substantial snow fall i will have to let my preassire down a bit i think.

90PSI sounds like a lot for a bike tyre, most tyres and innertubes are rated to much lower max PSI. Are you inflating above max rated or do you use special high PSI rated tyres and tubes?

Hi Fury,

The tyres are rated for 80 psi, I pump to 90' generally. But if I want a good long cycle I pump to 100 psi, that makes a big difference!

It's amazing being able to go 25 miles on 8.5ah mainly on level ground a few small hills.

I wouldn't ride in the snow, but I'm not sure if we will get any this year, time will tell.

try some 700C's at 120 psi
.. they roll nice and easy ! :wink:

..but wasn't there a report from a tyre company (Maxxi ?) that tested rolling resistance and concluded that these was little if any difference in resistance between tyre widths ???
I think the tread pattern will make a difference for sure, .... knobbly's are a bitch to pedal on the road.

Back in the day, I used to go to truck stops to get 100 psi from the air hose. That was in the 70's pedaling a cromo peugot ten speed. My cheap air pump would only go to about 50 psi. What a difference a rock hard tire made, I could coast forever it seemed.

Pattern matters. a center rib of some kind is very good for easy roll, even if the rest of the tire is big knobs.

I could not agree more, i use the Schwalbe land cruiser and i have to say that they are the best tyres i have ever had on my bike. Excellent rolling at 50-60psi and good grip offroad as well. I realy worry about goning up to 80-100PSI as i dont want to damage the tyre or tube that are rated for 60PSI. at 60PSI i can feel the tyre compress when rolling over things on the road or path so i gues thats not too good either lol.

Word of caution, if like me you run large tires (2" and up) that are rated for 80 PSI, running them at 40 is dangerous in turns. The tire can and will fold on itself causing it to loose grip. The results are not pretty.

I had not thought of that, I run 2.5 Maxxis Hookworms and do lower them a bit for comfort.

One reason I love my shocks. I can just run my tires nice and hard. 60 minimum, harder if the tire allows it. I still look for that center rib when choosing a street tire, even running em hard.

I've been running my Specialized Compound Control tires at 50psi front 60psi rear but after reading this thread I think I'll up that a bit. I'll try 70 front 80 rear and see if I can notice a difference. The tires are rated 100psi so can go even more for testing purposes.

On a side note I've noticed that slime tubes seal punctures more reliably at 50psi and up. When I was running less pressure I had more instances of slow leaks not sealing until I pumped the tire back up a few times.

Gary

60psi on my 1.5" slicks beat me up, at least the rear. I can get away with high pressure on the front due to my shocks. I run about 35psi in the rear, Kenda Kwest. My bike is SLOW to pedal without the motor. I can't figure out how you guys have any interest in pedaling an ebike without power. It's EASILY TWICE as much work as my 17lb road bike with 100 psi 700x25c tires. I had to use the motor last night riding with my girlfriend at 10-12mph, so as to not work too much. Going downhill isn't bad, but any uphill is a joke. My bike weighs around 58lbs and I have a geared hub motor that has barely any drag (maybe 5 watts).

I did do a rollout test, down a hill, ending on a hill on the other side, low speed. Running 60psi was about 4 feet longer distance than 35psi. If I have to get max range from my bike, I might go 45psi in the rear, 55 up front.

I tried a CST Cyclops 2.4" 26" on the rear. It seemed to hold speed about the same, maybe a hair slower, at 30psi. The problem was that the much taller tire KILLED my acceleration and climbing. My bike felt like it lost 7 amps, no joke.

Don't neglect the affect of WEIGHT on rolling resistence. That's the biggest determiner IMO. If I ride a basic mtn bike with the same tires at the same psi, it's soo much easier to pedal since it's 25lbs lighter, even once you're up to speed.

One of these nights if the wind stays calm, I may do a watt hour test on different psi. That's what really matters. But from what I've seen, I have never noticed a difference between 35 and 55 psi.

HI Veloman,

I love to put the effort into cycling to keep fit, and since April of 2011 I have lost just over 20 kgs, I am not really loosing any more because I can't get out as much this time of year. But it's not going back on. Diet change and no beer help a lot to keep it off!

The Continental sport contact tyres make so much of a difference it's amazing, they are very slick but I've never had a problem with grip in wet or dry. Pumped to 90 psi if cycling or back to the max rated of 80 if not bothered cycling.

But hills are defiantly where I notice the weight of the bike, but I put into a lower gear and do my best to get up, and that's when I use the motor mostly if I get tired and need that extra help.

When I started to cycle again in April, I was very unfit but my old motor the magic pie was too hard to pedal with the drag so that's why I got the mac and now I am able to cycle 14 miles and use as little as 200 mah to 500 mah out of my 10ah LiPo, that's on a relatively calm day with gentle breeze.

The tyres also have the advantage of being puncture resistant and they definitely are because this is the first year I've not got a puncture at all!

But no mountain bike can match a good quality racing bike. I can cycle 30 miles no problem on my brothers trek and hill climbing is so much easier on it, even he struggled to cycle my bike the same distance before I put the motor on it, only thing with the trek was I forgot my feet were locked into the pedals and fell off at traffic lights on my side and whacked my head off the road, the embarrassment was not fun!

dogman said:

Back in the day, I used to go to truck stops to get 100 psi from the air hose. That was in the 70's pedaling a cromo peugot ten speed. My cheap air pump would only go to about 50 psi. What a difference a rock hard tire made, I could coast forever it seemed.

Pattern matters. a center rib of some kind is very good for easy roll, even if the rest of the tire is big knobs.

Click to expand...

I had just such a machine and spent a happy three months cycling many thousand miles round France and Spain when I was about 18 years old. It always amazed me how much more lively my Peugeot was to ride compared to my friends bikes which were top of the range (at the time!) aluminium alloy framed tourers, I was convinced it was something to do with the different materials; maybe more flex and hysteresis in the aluminium frames absorbing energy.

I dunno. There is defintely a lively feel to the good vintage steel bikes. I have a gitane in mothballs in the shed, and still ride a motobecane that I converted into a comfort bike with different bars and a three ring crank. Can't pedal 52-11 no more. :lol:

Used to just ride like it was a fixie in that gear. Back in the day, my 27 pound peugot was pretty slick compared to the typical buddies bikes, 35 pound schwinn varsity or huffy and such. Got a chance to ride a pretty nice vintage schwinn paramount recently. Still steel, but about 26 pounds. In it's day, a racing bike. Lance loved his in his triathlon days. Same lively feel pedaling hard. The paramount rolled real nice on 100 psi tires.

If you run a tire at too low of pressure, you stand a good chance of getting pinch flats.