whitecat

Not much really. Since narrower tires need to be pumped up a bit more to have the same rolling resistance as the wider tires, it comes out pretty much the same with each tire at it's optimal pressure. And the difference in width is not that much to begin with. For example if you vent from 1.9" width to 1.4" width you might feel some difference, but probably not for this example that you asked. Keep in mind, that also with tires narrower then 1.75", tire also shrinks considerably in it's volume, and as a result gives a much harsher ride, and needs much better roads - narrower tire can easily get stuck in things like rails, wrong side oriented manhole covers, sometimes even cracks in the road surface. Keeping all that in mind, I have opted not to run narrower tires then 1.75" on my commuter. Just something to have in mind if roads are not that good where you ride - mine sure aren't.

PaulRivers

lol, every time someone asks "what's the difference in tire speed between tire size a and tire size b", there are always inevitably two answers -
1. There's no noticeable difference
2. There's definitely a noticeable difference



I'm not kidding though. Every time. lol

There is some sort of difference in speed...no one can seem to agree whether it's truly miniscule or if it's a big deal. I know that I get passed by guys on the greenway with big fat tires on my skinny tire road bike - the fact that they bike every day means they can still kick my ass, lol.

dahut

Aint it the truth.

At the extremes, the differences are bound to be noticable. Knobby softies vs. skinny 23's - that sort of thing.
The difference between a 1.5 and 1.75 slick is probably more between the ears than anything else.

At least it gives us something to prattle on about.

shizzy

I find it easier to maintain my preferred speed of 15MPH on my old Schwinn Le Tour then on my Trek MTB with slicks. when I get to work I find im less sweaty and have much more energy left.

FunkyStickman

I switched to 1.5's slicks my MTB, and it lets me keep up with the slower roadies on group rides (you know, the ones with hybrid bikes, knee surgeries, or weigh 100+ pounds more than me).

Plus they're blue. That has to make them better, right?

dahut

Easy there, Buck-o - you just named me, two out of three.

And sure, blue tires has to count for something. I mean how cool is that?
(I read somewhere that rubber is a washed out tan or grey color in its normal state. If I recall it was some asking about the light colored tires on a WWI reproduction aircraft. Carbon black is added to the blend to make tires the black we normally associate with rubber, and any other color will work as well.)

PaulRivers

Yeah, but saying the difference is "probably more between the ears than anything else" is to strong. Someone says they can't tell the difference between 28c and 32c. Then they say they can't tell the difference between 32c and 35c. They say they can't tell the difference between 1.25" and 1.5". They say they can't tell the difference between 1.5" and 1.75". They say they can't tell the difference between 1.75" and 2".

This is all probably true - it's difficult to tell the difference between minor changes in tire size.

But put this person on a bike with 28c, then swap out the tires for 2" - they'll *definitely* be able to tell the difference.

I would personally say the line where tires on a mountain bike become to skinny to be comfortable is when you drop down below 1.5" to 1.25". But I only have a tiny bit of experience with that. On a side note, I don't have to ride really terrible roads, and I haven't had a problem with my skinny road bike tires getting caught in manhole covers, railroad tracks, or "cracks in the road surface" since I was like...8. I do keep an eye out for that stuff - you don't want to go over recessed railroad tracks and anything other than a 45 degree angle - but you know, I find since I also have to keep an eye out to make sure I just don't ride off the road, ride into a curb, or try to ride over fallen tree branches, I can somehow manage.

I wish I had some 1.5" to 1.75" tire experience, but I don't...I suspect it's a rather arbitrary decision, though again since I don't have experience I cannot say for sure.

FunkyStickman

Glad to see you're on a bike, period. I've got no excuse, I'm not huge and I'm mostly healthy. I'm I'm not proud of always being the rear sweeper on group rides, but hey, somebody's got to do it, right?


True, rubber is naturally light brown, they add black coloring to it. And yes, blue tires on a blue bike gets lots of comments from the carbon fairies.

dahut

Like I said, its the extremes that'll get ya.

FunkyStickman

Funny thing about blue tires, when you ride them for a while, you can easily see where the contact patch is. Even at 100PSI, my Kendas have a much bigger contact patch than I imagined. I'll have to post a pic to show you what I mean.

Leebo

I commute on several kinds of bikes, mtb, touring and an older steel road bike set up for commuting. On my commute the mtb is almost as fast as the road bike, +- 3 min for 19 miles. I find myself not slowing down on the mtb for road hazards. My ride involves dirt paths and roads, potholes, curbs, gravel and bumpy MUPs. The road bike is faster on good pavement and slower on the rough stuff.

canyoneagle

I think there are many factors that can influence the average speed on a variety of bikes.

In my own experience and context ("race prep" training on very good quality rigid MTB with slicks vs. excellent quality road racing bike on the same loop with similar conditioning, 20-40 mile training ride distance) yields a difference of no more than 2-3 mph (20-21 mph average pace on the mountain bike, 22-24 mph average pace on the road bike). So, overall pace was about 10% faster on a racing bike from my experience.

This is in a high intensity, race training environment, with relatively steady riding (no traffic signals, etc).

So, I find that this small delta in pace becomes insignificant to nonexisistant in the commuting environment. Stop signs, traffic signals and other real world commuting realities essentially negate the small pace advantage that the road bike might have given me.

meanwhile

The gearing isn't the real problem. It's the air resistance.

meanwhile

Your pedalling technique must be abysmal. Seriously: you need to learn to spin.

meanwhile

Air resistance would be higher but, opposite to what most people think, rolling resistance would be lower if pressure was the same.

njkayaker

The runner stuff is interesting.

The key to figuring out whether it's "worth it" is to get some sort of numbers.

This following indicates that the effort of riding at 16 mph in a less aerodynamic position would yield 18 mph on the drops (approximately).

https://www.noping.net/english/

canyoneagle

+1
with a 44Tx11T, 26" with 1.5, spinning 90rpm (very sustainable spin), you're at 26-27 MPH. Bump the spin to 120 RPM (decent sprint), you have 35MPH.

njkayaker

Of course, people go wide (eg, mountain bike tires) to use less pressure.

dahut

And getting a new one, soon.



Carbon fairies - I love it! Im gonna use that one, if I may.

LesMcLuffAlot

Last summer in August, when I had my best fitness of the season. I tested this. I have a top end hardtail mountain bike that had a MSRP of over 5 grand in 2006. Top notch world cup worthy race bike. I put on 1.5 inch slicks and went for a personal best for my commute. I did a personal best time for my commute. 2 days later I used my mid-range cyclocross bike with 35mm cross tires and did a new personal best by over 1min.

I would say wheel diameter plays a big part. The 700c wheels seem to maintain momentum better. Gearing plays a part too. The mountain bike cassette has huge gaps in gearing which works off road but sucks on road. The gear you're in is too hard and the next easier one is way too easy. I could have been faster on my mountain that day if I had a more road oriented cluster.

Yes you can still go fast on a mountain bike. I have a 44*11 top gear. A good spin and good legs, you can see 29mph plus. 16:40 to 17:40 in the first video is at 27-29mph.




Recorded for your viewing pleasure.

The mountain bike with slicks.


Cross bike with cross tires two days later.


Case closed.

dahut

I dont know what all that proved, but it was cool. Helmet cam! He!! yeah, baby!
But you need to trim the weeds around your driveway. You can do that when you get back.

Thanks!

BassNotBass

My Huffy MTB now has a 52T chainring because a 48T was limiting... granted that was while drafting or with a tail-wind but nevertheless those sprints for a speed rush are now more exhilarating. Also my MTB bars are level with my saddle height so I can tuck pretty well when I need to by holding the bars closer towards the stem and letting my elbows drop as though I were doing chin-ups.

meanwhile

Has anyone mentioned this?

https://pfunwithpflug.blogspot.com/20...unon-road.html

A flat bar 29er came in third in a serious amateur road race with the help of the gravel roads that made a third of the route.

Leiniesred

Nope. Frontal area of the Mt. Bike with rider is simply higher than the roadie and rider.

PaulRivers

Lol, yeah - the guy says "Case closed" - I'm not even sure if he's saying they're the same speed, or that the road bike is faster.