16

Another possible cause is misadjusted rim brakes where the brake pad makes contact with the tire's sidewall.


11

The rear wheel is normal size (700), the front wheel is smaller (650). It was for aerodynamic reasons. By lowering the torso of the rider, the frontal surface of the rider became smaller. The configuration appeared first in triathlon and was later banned by the UCI in road and track events. Both wheels must now be of identical size i.e. 700.


11

Yes. It needs to be replaced. When the rubber tread is worn so far down the carcass is showing the tire is dangerous. The fabric carcass cannot provide grip like the rubber can so you risk losing grip in a corner and wiping out.


10

Do you both have a speedo on your bike's handlebars for reading the current velocity, (ie speedometers/head units/bike computers/) ? It can be very hard to ride on feel, so one of the better ways to pace a group is to pick a target speed that is not flat-out, and the lead should aim for that speed. When the leader feels its time to rotate, then you gently ...


7

Thorns generally don't make neat round holes as per your picture. While its not impossible, this looks more like a wear indicator, a hemispherical pit on the tyre's tread, intended to show when the tyre needs replacement by wearing off. If you can hold the tyre up to the light (when its off the rim!) and see light through, then your inner tube could ...


7

The logo is from a Carrera (Halfords) bike, so the wheel will have been on a Carrera originally. You can google the Carrera logo and see that the C is styled in the same way on their full logo. The 29 is simply referring to the wheel size, a mtb '29er' which has the same ETRTO rim diameter as a typical road/gravel bike, though widths can vary.


6

It will depend heavily on the cyclists and the ride. I assume here that both riders are equal - clearly if one needs some help they should take shorter pulls. In addition, trying to stick rigidly to timing is often unrealistic. A sudden burst of traffic from behind can lead to a much longer turn on the front, and potentially more recovery on the back. Trying ...


6

I had exactly the same problem in Shimano 105 road shifter. I solve it by wrapping bleed screw with PTFE pipe tape and it did tightened to damaged threads in bleeding port.


5

You have a few things to consider. First a Cannondale 56cm geometry is not identical to a Giant, Specialized or likely any other brand. Each brands designer has a specific goal in mind when they design a frame. So you can make a generalized statement that you may usually ride a 56cm it is not a hard and fast rule. One thing to consider is with the advent of ...


5

You have a Shimano 105 5603 series 10 speed shifter paired with a Ultegra 6700 series 10 speed rear derailleur, as those are both 10 speed they will work together. Those will not work with a R7000 series 11 speed cassette. Even if you thought you could just select 10 sprockets out of the 11 that does not work. Sprocket spacing is different between 10 and 11 ...


4

It depends very much how far you are going and how fast you are intending to ride. If you are doing a 25 mile 2 man time trial you are probably going to be swapping every 30 seconds. On the other hand if you are riding a 200 mile challenge ride it is more likely to be 5-10 minutes. As others have noted, the terrain and relative strength of the riders is ...


4

They're build QC tolerance numbers for side to side (lateral), up and down (radial), and offset (dish).


4

It appears that the cords holding the body of the tire to the bead have torn. Overinflation, hitting a rock, curb, or other obstacle, running the tire at too low a pressure can cause such damage. I'm sure there are a host of other reasons as well. It's also possible this tire was defective from the start. Hard to say at this point.


4

Percentile based formulas for crank length are trash. Femur length, health or special needs of all the joints in your leg, and the desired relationship between your saddle, knee, and pedal are all factors, as are the clearance needs of the bike, the type of riding being done, and Q. There is zero reason why a simple percent of your height would suffice. ...


3

Shimano Tourney TY SL-TX50 shifters are 7 speed, so you must have a 7 speed cassette (or more likely freewheel) on the rear wheel. An Acera derailleur is from a 9 speed groupset (or possibly its an older 89 speed one.) The Tiagra front derailleur is from a road groupset and depending on age could be 3x10, 3x9 or 3x8. You really cannot make any effective ...


3

Yes, you can put a rack on a CF frame, given the right rack. Namely, Tailfin makes racks explicitly designed to work with CF frames without rack eyelets, like "racing" road bikes.


3

A friend brought me a bike with this problem, and after halfway disassembling the brake, I realized that the problem was that there's a little plastic sleeve that goes over the end of the spring, so that it can slide easily when the brake is applied. You can see where it is circled in red in the picture, after being put back to the right place. That sleeve ...


2

You could get a beam rack that attaches to a seat post. Only issue is that you'll be limited by weight you can carry. If you have a https://www.sjscycles.co.uk/carriers-racks/tubus-adapter-set-for-quick-release-axle-mounting/ https://www.tredz.co.uk/.M-Part-Seat-Clamp-Mount_34111.htm?sku=79197&utm_source=google&utm_medium=cpc&utm_campaign=...


2

It's hard to get a better bike than a mountain bike for going up and down hills. Even a cheap one. The geometry is set up so it's controllable both up and down steep hills, and the gearing almost certainly goes low enough that you'll be able to pedal up even the steepest of hills (as long as you're strong enough to push the combined weight if you, your ...


2

Any Shimano compatible 9 speed road shifter like the Sora you linked will work. While it will be visually different it will perform the same function. The last of these models were produced in 2007. While the Sora shifters you are looking at may be lower on the hierarchy list, they are likely equal to or better than your nearly the 20 year old technology you ...


2

You'll really want to look at the specific geometry of the bike, rather than the seat-tube size. As stated in the other answers, standover height is important, and should be shorter than your inseam by 1-2cm. Besides that, Stack and Reach are probably the second most important measurements to consider. If you can't try on a bike in person for pandemic ...


2

It really depends on your training. I think nobody can give a definitive answer, especially since we don’t know your starting point (your average speed doesn’t tell much without knowing the duration, track, bicycle, conditions, effort etc. etc. etc.). Since you seem to be focused on speed: Speed mostly depends on your power output versus weight (yours+...


2

If we were to think about an "optimal algorithm" for two people exchanging positions while drafting, we could consider one "event", which is the condition to exchange positions, and one "state", which is the period while one same rider is at the front. It seems to be this is a good description for this optimal algorithm: The ...


2

You're still young - at 15 you are still growing, so work on endurance and technique, and not too much on raw power. And remember its not about ultimate top speed, there's got to be an element of enjoyment too. So work on enjoying your time on the bike, but also have a life off the bike.


2

It sounds a bit like you want the computer mounted centrally and in front of the stem. As you know Wahoo computers all come with an out front mount that attaches to the handlebar. I think that you are looking for something that doesn't clamp there, perhaps because you have accessories. In general, Googling for "out front" mount should identify most ...


1

We try to avoid specific product recommendations here, but there are a number of computer mounts that attach directly in front of the stem's faceplate, through a pair of extra-long bolts into the stem. Also, Ritchey makes a universal stem mount (which mounts the same way). You could combine this with a 3D-printed GoPro adapter.


1

This is really an unanswerable question. You might have only moderate potential or be the next Peter Sagan. We also know nothing about the area or environment you ride in - that ~17pmh/27kph in dead flat roads is not as good as on roads with a lot of climbing. Also, how long are you holding that average speed for? All you can really do is focus on getting ...


1

As many have pointed out in comments and answers, bike sizing is not an absolute but a “fit window,” where it is possible more than one frame size could work for a particular rider. That said, given you dimensions, the fact my height and inseam are within a cm of yours, and the fact I have trialed risen a large number of brands and sizes I can say with a ...


1

I did some looking around and was surprised by the lack of options for a proper ramped and pinned 42t 130 middle. But, there's still TA, the Alize model in this case. Don't get a non-rampy chainring to use with STI. It's too much of a compromise. FSA has one too.


1

This is a common conundrum for new bike commuters! Yes, there are certainly bikes out there that will be better for you at hill-climbing or commuting in general. However, it's hard to know if it's worth the investment until you know for sure that you want to continue commuting by bicycle... but it's hard to know if you want to continue commuting by bicycle ...


Only top voted, non community-wiki answers of a minimum length are eligible