canklecat

After getting my first flat with my new-to-me bike I noticed some odd wear in the sidewalls of both Specialized Hemisphere 700x38 tires. The tread was good, no cracks. Just a tiny shard of metal worked its way through the tread and poked a pinhole through, just enough to slowly deflate the tube but with no perceptible tire damage.

However I see some slight sidewall wear on both tires with a bit of the underlying fabric peeking through. (See attached photo.) The brake pads seemed to be adjusted with plenty of clearance to avoid contact with the tires, but I'm wondering whether the wear was due underinflation by the previous owner causing the tires to compress enough under load to contact the sharp shoulders of the pads, or whether the wear was due to abrasion against the rims. I've run my fingers along the rims and they feel smooth.



Anyway, I'd hoped to find another set of Specialized Hemisphere 700x38 tires, but no luck. Yeah, the Armadillos and other "better" Specialized tires are available, but the regular Hemisphere's feel great and I'd rather get a duplicate set just in case. Great compromise feel between speed and sure handling on patches of loose sand and gravel even on turns.

However, I see a good sale on Vittoria Randonneur RFX "City Tires" which may be close enough for my riding: about 75% pavement, mostly on shoulders with the usual hazards of broken glass and debris; about 25% unpaved trails and those rutted dirt and gravel strewn paths that pass for sidewalks in Texas.

Unfortunately the Vittorias on sale are available only in 700x46. I'm concerned about whether the above mentioned sidewall wear might be worse with wider tires.

FWIW, my rims are single wall aluminum 622x20 Alex Z-1000, nothing special. The 700x38 Specialized Hemisphere tires fit loosely enough on the rims when deflated that levers are unnecessary. I'm guessing 700x46 are within the range for these rims.

Little Darwin

That damage does indeed look to me like someone rode the tires under-inflated, This is further evidenced by the valve being at that odd angle that usually happens when you ride under-inflated tires. Unless you ride the new tires under-inflated wider tires shouldn't make this issue any worse.

Does your bike have clearance for 46 mm tires?

canklecat

Thanks. Underinflation may have been a factor. I rode the bike a few times before getting a pump, around 1-5 miles per trip at very modest speed on pavement. I think the pressure was around 40-50 psi when I got the pump. The Specialized Hemispheres recommendation is 75-100 psi. Now I usually keep it around 80.

Seems to, but I'm just eyeballing the brakes and frame. It's a stock Specialized Globe Carmel from 2009. Brakes look like Promax low end linear pull brakes (in ye olden days I would have call these side pull), with enough adjustment to clear slightly wider tires. Frame looks wide enough.

BlazingPedals

Make sure the brake pad isn't overlapping onto the tire. I say that because it looks like it's pretty close based on the wear showing on the rim.

canklecat

Yup, the pads were a bit close when I got the bike. I moved the pads a bit away from the tire. Some of the tutorials I've seen recommending brake pad placement don't seem to account for normal sidewall bulge with some tires.

These Specialized Hemispheres have excellent tread but the sidewalls feel rather thin. I'm hoping this set will last until I can find a direct replacement, or a set of the Vittoria Randonneur RFX in something closer to 40 rather than 46 or 48.