# change in mph from road bike to CX bike for commute



## Montobo (Sep 6, 2012)

This question is based on a proposed new bike build for me. Right now, I commute on a road bike with 25 mm conti gator skin clincher. For certain reasons, I am thinking of a cross bike with tubular tires, 32 mm, "fast rolling," there are several choices in tires, haven't picked it. This way I could alternate between the platforms. I would rather not discuss tubular vs. clincher. Because my route is VERY hilly with some steep climbs, a good mph right now:

15 mph with 25 mm tires. 

What is the estimated mph (ignoring weight difference in bikes) for the CX 32 mm width? Let's assume ideal conditions for road, weather and for bicycle maintenance and for tire pressure.

Thanks a lot for helping me plan.


----------



## Scott B (Dec 1, 2004)

I'm going with "some, not much". How rough are the roads? The smoother the roads the greater the advantage of a skinner tire. If you're climbing a lot rotational weight would have an impact on speed.

I'd think the knobs on a cross tire wouldn't be ideal for road. Also, most have a softer rubber compound, so wear life wouldn't be as good. Those seem like bigger downsides to me. How about a wider road tire? 28mm Gatorskin or a 32 mm Schwalbe Marathon Supreme?


----------



## 32and3cross (Feb 28, 2005)

I will second what Scott B said. Most any 32mm cross tubbie you find even a low profile one will have a soft compound because they are designed withe racing in mind not long mileage and they are damned expensive. 

Im sorry I know you said you didn't want to discuss it but I think using tubulars for commuting is going to limit you tire choice to things that just are not correct for the application.


----------



## Steve B. (Jun 26, 2004)

My one way is 25 miles, all hard surface, some bike trail. 

On my tourer/commuter (27-30lbs Miyata tourer) with rack, fenders, 32mm slicks, I typically avg. about 12.5 - 13 wind dependent.

On my "fast" commuter (Soma Smoothie) with 28mm's, no rack/fenders, I can avg. 14 - 14.5. 

So yes a difference, that I pretty much never really pay attention too.


----------



## Chainstay (Mar 13, 2004)

The weight and relative aerodynamics of the two bikes is also a factor. My bike with cross tires is about 6 pounds heavier than my 23mm road tire bike, plus I lose on rolling resistance and have a more upright riding position. On a hilly route I am 2 mph slower. I actually go even slower because the bike does not inspire me to ride as hard.


----------



## Montobo (Sep 6, 2012)

Thanks. By ideal conditions for road, I mean that the road surface is ideal, smooth, excellent road. Also, there are some choices with tubulars. I guess I should explain that, although the road surface is ideal, I want to leave a margin of safety. Maybe there is a 1 in 1000 possibility that, to evade danger, I need to pull off the road a bit. So for that, I want to be riding something wider than 23-25. Maybe that would be in the 27, 28, 30 range. Road tubulars go up to 27 and then fast rolling cyclocross come in at 28, 30 (tread is not smooth, though). I am thinking there will be enough choices. I could experiment. Thanks for the help.


----------



## chocostove (Jan 31, 2007)

If you're concerned about tire control in emergency situations a good 28-32mm road tire is gonna hold up better. The small weight penalty of clinchers is a small price to pay compared to hassle of using tubular for commuting and there are some great tires out there.

As someone who uses Kenda small block 8's on my secondary commuter(which is seeing full time use right now, 30+ miles daily) There is a loss in traction compared to a smooth tread tire. 

I'd much rather pair a wider rim with a wide tire that try to deal with the threat of a puncture on a tubular. I can patch a tube in minutes in the rain and cold. Glue has to dry....


----------



## Montobo (Sep 6, 2012)

I have slept on the clincher vs. tubular concept and have come to believe (clinchers) despite my otherwise stubborn-ness. I still have tubulars on my other bike. Thanks for the help.


----------



## nhluhr (Sep 9, 2010)

I have a high end carbon road bike on 23mm road tires and a 'budget' aluminum cross bike set up for road duty with road gearing and 28mm road tires and 35mm fenders. There are so many differences between the two bikes to account for small differences in speed but I think the two bikes make for roughly 1mph difference on my daily commutes (44mi round trip).

To be honest, I think the winter clothing I tend to wear with the cheap bike slows me down more than the bike, but I reckon the biggest factors from the bike are tire rolling resistance and aero drag from the fat tire and less aerodynamic wheels.


----------



## homebrewevolver (Jul 21, 2012)

45685


----------



## axlenut (Sep 28, 2010)

Hi, me thinks if you are only going to use the bike on the pavement you should avoid any tire that has knobby tread. I think you would be much better off with a semi slick 32MM city tire then any CX tire. The main reason is tread squirm under corning and the higher rolling resistance. I love bigger tires for commuting but they need to be semi slick.

Later, Axlenut


----------



## nhluhr (Sep 9, 2010)

axlenut said:


> Hi, me thinks if you are only going to use the bike on the pavement you should avoid any tire that has knobby tread. I think you would be much better off with a semi slick 32MM city tire then any CX tire. The main reason is tread squirm under corning and the higher rolling resistance. I love bigger tires for commuting but they need to be semi slick.
> 
> Later, Axlenut


Definitely. Before I went to the 28mm road tires on my winter commuter (cross bike), I did a few trips on the 35mm knobbies. The additional rolling resistance was definitely noticeable. The only reason to stick with knobbies would be snow or dirt on your daily rides.


----------



## serfur1 (Sep 17, 2007)

Go with schwalbe 700x32 marathons, theyll be just as fast as your 25s, well at least not noticeably slower.


----------

