Introductions - Greetings from Fresno

Hello, all. I'm getting back into this after a hiatus of about 8 years, and I recently upgraded from a bad ol' chain-store bike to a new Giant Cypress SX hybrid. The chain-store bike got me through a full century this spring (my first century since 1995, yay), but it was time to stop being laughed at. So I'm not a full-fledged new-newbie, but I've been out of it for long enough that I certainly have many newbie-type questions.

So I'm taking the Cypress all over the Valley and over to the Bay Area, racking up 819 miles since I bought it on June 2. Of course, with summer now in full effect here in the Valley (102F yesterday and 101F today), I'm starting to cut back -- although I'm signed up for the 100km option of Climb to Kaiser at the end of the month.

Of course, I wouldn't be here unless I had a question -- and here's mine.

The Cypress came with 700x28c tires. After a particularly nasty episode with glass and flats over this past weekend, the local bike shop decided it was time for me to have a 700x38c tire. They only installed it on the rear rim, though -- which strikes me as a really, really stupid thing. I bought a second 700x38c tire ("on sale" for $5 a pop) and figured I'd replace the front myself, but I'm suspecting that I've been taken for a ride and that mismatched wheels are a Very Bad Thing Indeed.

I'm a "more robust" rider (5'11", 185 lbs), and our area roads are particuarly glass- and pebble-strewn, so perhaps the 700x38c's are good for me, but I'd like to hear it from someone else before I go ahead and make my front and rear wheels agree with each other. And how much of a speed penalty will I pay?

So I'm taking the Cypress all over the Valley and over to the Bay Area, racking up 819 miles since I bought it on June 2. Of course, with summer now in full effect here in the Valley (102F yesterday and 101F today), I'm starting to cut back After a particularly nasty episode with glass and flats over this past weekend, the local bike shop decided it was time for me to have a 700x38c tire. They only installed it on the rear rim, though -- which strikes me as a really, really stupid thing. I bought a second 700x38c tire ("on sale" for $5 a pop) and figured I'd replace the front myself, but I'm suspecting that I've been taken for a ride and that mismatched wheels are a Very Bad Thing Indeed. And how much of a speed penalty will I pay?

There is no problem at all with having different tire sizes front and back. I think that you will benefit from having a thick tread no matter what size tire, though. I think wider tires are sort of a drag, when it comes to speed. But look at it this way, you'll get stronger from more weight and more friction. You could always change back, if you need to be speedy for some event.

Good luck with the summer riding. Don't fall into the delta.

You might consider Specialized Armadillos - they have a good reputation for getting through glass and stuff.

To me, this would be a better solution than a really wide and probably slow tire.