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If you are asking how to calculate the maximum capacity of the chainrings and cogs, based on looking at the derailleur, then it's not going to be as easy as just looking at them.
Finding a derailleur to fit your chainrings/cogs based on just the chainrings/cogs is going to be a lot easier than finding chainrings based on looking at your derailleur. HOWEVER, ...
28
Belt drive + Internally Geared Hub is a popular combination.
Existing systems are based around a gates carbon belt drive. See the Breezer Beltway series bikes. Also Reeb Cycles began offering belt drives for mountain bikes when they first came to market.
Also, now there is a breakable belt system called Veer that doesn't require a frame cutout (though uses ...
25
In 2001, Kyle and Berto published a comparison of the mechanical efficiency of several configurations of derailleur and internally-geared hubs in Human Power, which you can find here. Among the systems tested were a Shimano MTB derailleur system, a Sturmey-Archer 3-speed hub, the Shimano 7-speed Nexus hub, and the 14-speed Rohloff hub. MTB derailleur systems ...
18
This is one of those questions that can start arguments between bike mechanics--to cross or not to cross the derailer cables. Crossing appears to be becoming more common on new bikes, if the cables aren't internal, but it's also going to depend upon the bike. Smoother shifting is reported by some from crossed cables. I would talk to the mechanic at your LBS ...
18
If you carry a multi-tool which happens to include a chain tool, you could also convert your bike to a single speed. If you do so, you would have to replace the chain afterwards as well (since you shorten it) but in some situations it could get you out of a rural area.
If you do so, carefully select the gear you would put it in, as you won't be able to ...
16
Jan Heine performed some wind tunnel tests of "Real World Aerodynamics" a few years ago. A link to a blog post (and the results published in Bicycle Quarterly) can be found here. Those tests cover only one component (the aero drag component) of commuter-type bicycles vs. "racing" bikes.
If you want to make your own apples-to-apples comparisons of ...
16
You can see in the video how the teeth on the cassette rotate quickly at the moment it slips(at :05 seconds), while the spokes of the wheel actually stay slow, then jolt forwards to catch up. This means that the freewheel mechanism in the rear hub is failing to engage.
It's actually quite dangerous because as it gets worse it could cause you to lose ...
16
You pays your moneys and you takes your chance
Answer Maybe genuine, but just as likely not.
Essentially by buying discount, you're circumventing any quality and control process from the brand owner.
Costs are a strange thing - what costs you $40 in the shop retail, might be sold on sale for 20% off and the seller isn't making a loss. The various ...
15
This type of problem has 5 likely causes, listed in order of elimination.
Bent dérailleur hanger, or Bent derailleur cage. (Your derailleur hanger looks straight, but the cage appears slightly twisted in the upper photo. Could be the angle of the shot, though.) Edit: This turned out to be the correct answer, after all.
Bent, twisted, or sticky chain link.
...
15
http://www.landriderbikes.com They were very heavily advertised several years ago but currently they seem to show up more on craigslist than on TV.
14
"Nothing is so broken you cannot make it worse" - breaking a perfectly good chain in the field, miles from nowhere, with a light weight emergency tool, would be my very last resort.
This will only work if the broken end is not too frayed. Remove the cable completely from the outers and the shifter. Thread the cable though the barrel adjuster on the ...
14
The general idea of "lever drive," or a reciprocating pedal motion instead of a rotary pedal motion precedes even the invention of the modern diamond-frame bicycle--consider the Special Star from 1886. More recently, there was the Facet Biocam, the Alenax, and the Wall Walker.
Within the world of reciprocating drivetrains, the String Bike is interesting in ...
13
If the teeth on the jockey wheels appear to be in good shape then you probably have nothing to worry about. Many jockey wheels use bushings instead of bearings, and either way they are not going to spin for very long just because there's not much weight to them and therefore they don't carry much inertia.
If there is noticeable resistance when you try to ...
13
You have a double front, right? The usual advice is to not shift into the highest 3 gears in the rear cassette when in front the chain is on the large chainring, and to not shift into the smallest 3 cogs, when the chain in front is on the small chainring.
This prevents 'cross-chaining', which wears the chain fast, produces noise and difficult shifting. ...
13
Another suggestion: Scooter it.
The bike is functional but the drive train cannot transmit power.
So one solution is to scooter along with one foot on the opposite pedal, and your other foot pushing directly on the ground. This can be uncomfortable, so rotating your saddle ~30 degrees to the opposite side from where you're standing can give your hip ...
12
If you can, with the chain in one of the middle cogs in the back, shift to each of the front chain rings then your front derailleur is likely in proper alignment and adjustment. This question and answer cover how to adjust the derailleur if you want to learn how to do it yourself.
What you are describing, shifting to small ring in front and small cog in ...
12
I have ridden one - it used weights thrown out by centrifugal force and springs to move the derailleur in and out. Horrible is all I can say. Maybe it was me not being used to it, but things like not being in the gear you left it in, and less than smooth changes - which you have not idea when they are going to happen, especially under power. The only ...
12
Well I thought we needed an answer to this, so I just phoned the shop. He's a nice fellow (as you can tell from the vid) and said that his mechanic is convinced that this method works to free-up seized and corroded mechs. Apparently dousing it in something like GT85 and lighting it for a very short time boils in the lube, and works.
I assume that the ...
12
Derailleurs, fortunately have been fairly standardized. Simple specs like these can help you determine what derailleur is best for your bike. Here's a brief overview of some of these:
Maximum capacity: The maximum number of teeth between the largest and smallest rings. eg. 48T-22T = 26T.
Top gear teeth: The range available for the largest ring. Any size ...
12
Derailleurs will last almost indefinitely. The jockey wheels will wear out in time (tens of thousands of km) but the rest of the mechanism shouldn't see significant wear.
12
This is an odd question. The sentiment that the only security here is physical security is correct. Think about the following:
The Shimano Di2 components are not mated/matched to a specific computer or instance of E-Tube software. So there's no 1:1 relationship.
Therefore, any computer equipped with the SM-PCE1 or SM-BCR2 programming cables can be used to ...
12
The derailleur is there to act as chain tensioner. In a frame intended for derailleur the rear wheel can't be moved to tighten the chain, so a separate spring-loaded chain tensioner is needed. The cheapest and ugliest way is to just use whatever derailleur was on the bike before conversion.
11
One point that seemed to be missed in the answers so far (though I'll admit I didn't read every word) is that indexed shifters are only a small part of indexed shifting.
It used to be that you needed friction shifters because, in order to shift to a larger sprocket, you had to "over-shift" substantially -- push the lever beyond the point where it would ...
11
A front derailer is a bit more complicated than it looks, and can be quite complex to adjust if you're starting from zero -- just having installed the unit.
There are five (and a half) adjustments --
Height, sliding up and down the seat tube.
Rotation around the seat tube.
Low limit
High limit
Cable tightness
Generally height is such that the derailer, ...
11
Trek had a bicycle a few years ago named "Lime" which had 3 speed automatic gearing. I don't think it sold well. It used a gearing system called "Coasting" that was created by Shimano and actually controlled by a computer chip from signals from the front hub.
"A dynamo is fitted on the front hub that gauges the revolutions of the wheel. It sends this ...
11
From your photo, the left pulley (beefier, with metal bushing) is the top one, which goes closer to the cassette.
I know that because that's how things were in every shimano derailer I had over the years, and I think that makes pretty much sense, since the beefier pulley (the upper one) actually shifts the gears, while the bottom, thinner one is only an ...
11
For the same reason you can't have a fixie with a chain tensioner.
The load on the chain when slowing a fixie is too great and in the wrong direction for a derailler or tensioner to hold. The cage will be pulled forward and your chain will skip make a nasty noise and most likely come off or break something expensive.
11
20,000km's in 2 years on Ultegra Di2. It performs very well. Shifts are smooth, crisp, quick and effortless. I have a few other road bikes running various mechanical shifters, but have preferred the electronic shifters during the past two years. No need for adjustment due to no more cable stretch. The front derailleur auto trims and follows the rear ...
11
The picture is a RD-M780-SGS long cage.
Shimano have three codes for rear derailleur length:
Short - SS
Medium - GS
Long - SGS
I'm not aware of where this is printed on the RD though so not so helpful.
However Shimano only have one non-clutched XT Dyna-Sys (10 speed) RD the RD-M780-SGS (long cage 43t capacity). The clutched (shadow+) RDs come in GS (...
11
The allen is almost certainly metric. Both 2.5mm and 3mm are reasonably close to 7/64 inch. 3mm is a very common size on bikes. If you are going to do any work on a bike you need metric allen wrenches.
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