Beating the system - the cycling commuting section
13 posts • Page 1 of 1
I would like to have your view on what width of tyre I should go for to commute. My bike is a Giant Transend 1 (it is a hybrid bike, not a racer) and currently I have 35mm tyres on it (which I used to cycle accross Australia with!).
- Do you think it would make a significant difference if I was to get narrower tyres?
- Can I tell how narrow a tyre my wheel can take?
selling my OPTIMA Lynxx Recumbent bike = $2,100 / Sydney
This is a difficult question to answer as comes down to the differences in the tyre you have now versus the tyre you intent to run as well as how comfortable you want to be (tyre pressure). It also depends on how fast you intend to ride.
The advantage of thinner tyres are higher pressure and aerodynamics. If you don't ride that fast, then aero won't be too much of an advantage. If you are happy to be less comfortable with thinner tyres then they may work for you. The main reason thinner tyres roll faster is due to to the higher pressure, as wider tyres actually roll faster at the same pressure.
http://www.schwalbetires.com/tech_info/ ... resistance
I'm currently experimenting a bit with tyre size and I have one bike with 58mm and another with 24/26mm (all measured) of similar construction. So far I'd say for the average person there isn't a lot of difference in roll as long as you pump each up hard enough for it's size. By running the extremes I'm trying to determine if you can get similar roll with more comfort. So far I think the bigger tyres offer a better roll/comfort compromise. The thinner are a bit faster and are liveable for comfort if you are on a regular course, but if you don't know the roads to compensate for the roughness, thin tyres can be too uncomfortable and bordering on dangerous.
Usually the minimum should be 28mm on a hybrid rim. To know for sure, you need to take the tyre off and measure the internal diameter of the rim.
I run 23s on rims as wide as your rims. It can be done, but not recommended by manufacturers. You will have less rim protection with narrow tyres, this may be the reason.
Some other light reading:
http://www.rivbike.com/article/componen ... tire_chart
http://www.slowtwitch.com/Tech/What_s_i ... _1034.html
http://www.slowtwitch.com/Tech/What_s_i ... __955.html
http://www.bikeradar.com/news/article/c ... gium-25190
http://autobus.cyclingnews.com/tech.php ... ardennes08
http://www.training4cyclists.com/how-mu ... lpe-dhuez/
http://www.cyclingnews.com/features/tec ... eel-energy
My old hybrid had 25mm tyres. The new bike has 28mm. Rolling resitance has reduced, as has weight (weight that you have to turn takes efforts)
the 28s took a while to get used to - especially in the wet but am happy with the width.
EDIT: I should note that I would be cautious going any less than 28mm
What surfaces are you commuting on?
Personally I'd go with a tyre that won't puncture (much) and that makes the commute a bit more comfortable. Reliability is #1 for a commuter. You won't save any time by going a narrower tyre while commuting because of lights etc. I use Bontrager Race Lite Hard-Case 700x32c. I wouldn't want anything narrower, but I do ride some pretty rough/buckled bike path.
OK well I've run this test to the extreme with the thinner tyres running at correct pressure for width and the 58mm tyres at a pressure I subjectively found as a good compromise between grip/handling/comfort versus speed. So far that has worked out to be 33psi in the front and 38psi in the back.
I tested on a 2 hour ride for each over the same course with the same computer. The wheels were calibrated for the computer at the tested pressure using the 10 wheel rotation method weighted, at the same place. So everything should haved measured accurately. However there are significant differences in the bikes with one being a MTB and the other being a road bike setup for commuting/touring. The saddle to bar was about level on the MTB and saddle to bar drop (to the hoods) was 3cm on the road bike. Flats on the MTB and SPDs on the road bike. I believe these tyre widths would be typical for these types of bikes as you can't fit 58mm tyres on a drop bar style bike or even most hybrid/commuter/flat bar bikes.
Results so far:
Difference in average speed was 2.8 Km/h.
Difference on the flat was ~4 Km/h.
2.8 Km/h average doesn't sound like much, but worked out to be 15 minutes longer for a 2 hour ride.
I'm planning to do more of these rides to get a better long term average. I like both bikes on this ride for different reasons, but if there are going to be many people on the paths I prefer the rigid MTB for its better braking and better handling over soft/rough ground.
thanks all for the interesting and insightful feedbacks, much appreciated!
selling my OPTIMA Lynxx Recumbent bike = $2,100 / Sydney
Interesting statistics. I run the same wheels and tires on my commuter and every day the ride times are different. I too get variations of 2 - 3 kms - sometimes faster, sometimes slower. How do you measure the placebo effect? Whether your legs are fresher or not? Whether you pushed it or took it easy?
You can control variables such as tire pressure, tire size etc, but you can not control variables like perceived effort and exertion, which I would suggest are just as important.
On further thought, you are correct. I think the bikes are too different to get anything more than an indicator, so I probably won't bother to continue.
The best way to do this would be with a power meter with the same bike and just different wheels/tyres. Until power meters become cheap, I won't bother.
[I had better be more careful of what I post too, since I can't edit my previous post now. ]
TG's scenario is a better one to go by since he is using the same bike just with different wheels.
Last edited by Nobody on Sun May 22, 2011 2:36 pm, edited 3 times in total.
I have two wheelsets. One is 700c and I run 23mm Conti GP4000s tyres. The other is a set of Michelin XCR Dry2 tubeless in 26x2.1".
The former is faster by about 5 minutes on my 1 hour 20min 29km commute, and I like the acceleration and higher top end speed. Wet weather grip with the Conti's is outstanding, although braking is nowhere near as good.
Nor do they provide anywhere near as good shock absorption and the rear wheel in particular requires regular truing as I'm not the smoothest rider and hit panel edges on footpaths along Warringah Road a lot more than I should. (Yes, I know I'm not supposed to ride there, but I'll take the fine rather than deal with grumpy drivers. Those who know my history with that piece of road understand why).
On the other hand, the 26x2.1s don't roll quite as well but I have to be a lot less careful and the ride to work becomes a lot more playful. Jumping off kerbs and bunny hopping roundabouts in quiet back streets become the morning's entertainment.
I was a bit surprised the difference was only about 5 minutes to be honest. There are some longish climbs on my route, which may be an explanation. The 26x2.1's feel like a lot more of a workout.
"People have a right to their own opinions, but not their own facts. Evidence must be located, not created, and opinions not backed by evidence cannot be given much weight." -- James W Loewen
love commuting on fat 26ers. there's frequently roadworks, detours (e.g. due to flooding), debris and other obstructions on my commute that require x-country excursions, kerb hopping and other stuff that leaves the roadies scratching their heads while i blow straight past
Well I just swapped some Michelin PRO Optimums 700x25 off my Defy onto my seek. I had 28mm Vittoria Randonneurs and the bike feels like I've strapped a rocket to it.
Once you can climb hills on a bike it's all downhill.
Hopefully I'll know what that's like..... one day.
13 posts • Page 1 of 1
Who is online
Users browsing this forum: No registered users