# New to Road Bikes--Bumps and Curbs v. Tires?



## Lawfarm

Just started putting serious miles on my Trek FX 7.6 (I know, I know...straight bars does not a road bike make), which has 700x28c tires on it (generic Bontragers). A lot of the bike paths and such in the area have significant bumps at street intersections--where the sidewalk has either heaved or fallen...and a lot of areas I ride have street cracks and other potential tire threats. Coming from MTB world, these things used to not concern me. But now riding on a skinny slick, I'm trying to gather some background knowledge about what does and does not pose a significant threat to tire integrity. So I'll pose a few examples and see what the collective wisdom is:

1" bump.

2" bump.

3" bump.

Going _up_ a standard curb.

Coming _down_ off of a standard curb.

Other?


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## mdmoore99

Hop the bike. Unweight the bike over small bumps, hop railroad tracks, similar to a MTB unless you just plowed over everything before ?

Study: http://www.youtube.com/watch?v=5z1fSpZNXhU


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## JCavilia

The size of the bump isn't as significant as the shape; i.e., the sharpness of the edge. The issue is whether the tire will be compressed enough to squeeze the tube against the rim and cause a pinch flat. That's a function of pressure, which is determined by the force and the area -- the smaller the point, the higher the pressure you get. So a speed bump that's 4 inches high but has a rounded shape may be no problem, even at speed, while the sharp edge of a 3/4" high pavement joint may be trouble, if it's sharp enough and you're going fast enough.

As the other poster said, roadies learn to unweight to absorb bumps (when they see them). Sidewalk joints can be a real nuisance, and you should learn to unweight for them. Pull up a little as the front wheel hits, then shift weight forward to let the back ride up. Street cracks are less often trouble. Potholes you ty to avoid when you can

Riding off a curb takes a little finesse in absorbing the shock, put will rarely cause a pinch flat if you're landing on a smooth surface. Riding up a curb on a road bike takes real skill. You really have to actively lift each wheel in turn. Not many riders attempt it often.

Skilled roadies can bunny-hop straight up (or sideways) several inches to avoid obstacles. I've seen pro racers get squeezed against traffic islands by pack movement, and hop sideways onto the curb, ride along the top until there's an opening, and hop back down.

Your 28mm tires are a good deal more forgiving than the 23s that most roadies are on.


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## laffeaux

If you're coming from a mountain bike background, going up and over curbs at a slow speed is not a big deal - if you do it smoothly. Wheelie the front wheel and then unweight the rear as it follows and there's little impact on the wheels. It's more difficult to drop off of curbs without causing an impact, but if you go slow and are careful you can do it without a harsh impact.

As the others said, try and avoid sharp-edge impacts. If you feel a strong jar to your body, your wheel is feeling the same thing. Too many of these, or one that is "too much" is going to make your wheels and tires really unhappy.


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## mcsqueak

I don't personally go off curbs on my road bike (running 700 x 23c tires) because I'm too worried about damaging the tube or rim, or popping a spoke.

However, sometimes bikes can take more abuse than you'd think. I took my Felt down a small set of steps on accident (thought it was a ramp, but discovered otherwise after it was too late, and the actual ramp was over to the left about 10 feet...). I was going at speed (probably 18-20 mph) and basically skipped over the steps because I was going fast. No popped tube, no broken spokes. I was pretty amazed.

For going up small bumps, like when a driveway entrance doesn't meet the street well, say 1"-2" inches of height, I'll stand up and pull up on my bars so that I lift my front wheel over the bump, then stay standing as my rear wheel passes up and over the curb. No problems yet. I ride clipless pedals but haven't really mastered a proper bunny hop.

I don't usually attempt to go off full-height curbs, or up them for that matter, just to prolong the life of my tubes and wheels. I'll find a driveway or wheelchair corner cut, or actually dismount my bike and take it off the curb if there isn't any other choice.


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## Fai Mao

I think as others have said that as long as you unweight the wheel and go slow you'll be OK. The bigger problem that I notice with MTB riders is that they often have a cadence of about 45, tend to push too high a gears and do not seem to be able to ride a straight line. Work on your cadence and line as well.


A little off topic but you mentioned it:

Flat bars are actually fine on a road bike if you like them. I have four bikes and three of them have flat bars, none of them are mountain bikes.

I think the supposed advantage of extra hand positions on drop bars is over rated. Most riders spend about 80 to 85% of their time on the hoods anyway and a flat bar with a set of bar ends is easily as comfortable for any ride. (Please note. I just spent two weeks going from from Hong Kong to Shanghai on a flat bar bike and plan to do Hong Kong to Beijing next spring. I rode between 80 and 100 miles a day COMFORTABLY on the bike below and it has flat bars. Depending on the roads I averaged between 10 and 16 miles per hour per day. There were floods in part of the route and I had had to go really slow for two days)


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