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rear entry drop-outs vs conventional bottom entry drop-outs(10 posts)

rear entry drop-outs vs conventional bottom entry drop-outsomar
Sep 30, 2002 5:45 AM
I'm about to spend a bunch of money on a frame with rear entry drop-outs. Something i've never dealt with before. Whats the technical diff, if any, on drive train, changing out flats, personal bias etc. Appreciate any input.
re: rear entry drop-outs vs conventional bottom entry drop-outsSteve_0
Sep 30, 2002 5:56 AM
I'm presuming by 'rear entry' you mean track-drops.

Track drops are good for FG and SS setups, where chain-tension is critical.

Even with FG and SS setups for road, theres some minor drawbacks; Extra step in removing the wheel and as you move the wheel (to tension the chain), the rear-brake may misalign with the rim.

Typically, trackdrops are used in conjuction with solid axles, which means youre carrying a wrench for roadside repairs. Not to say (iguess) you can replace with a quick-release, but I've never seen on.

If your going with a geared bike, trackdrops provide no adavantage. If your going FG or SS, trackdrops are a huge advantage over vertical, and a slight disadvantage over semi-horizontal (in which the brake will remained aligned).
SS and OR'sEager Beagle
Sep 30, 2002 6:03 AM
I run a QR on my SS without problems. However, I have the little screw-in bolts to set the wheel position in the drop-outs (they screw in-out from the rear and the axle rests on them . If you don't have these, the wheel is prone to shift about under hard peddaling.
SS and OR'sSteve_0
Sep 30, 2002 6:08 AM
I run QR on my FG; but my FG has horizontal drops. Never had a problem under any load.

Of course, having said that, i'm sure i'll need to realign my rear this afternoon.
How are building the bike up?timfire
Sep 30, 2002 10:05 AM
It's important you mention how you intend to build the bike up, meaning is it going to be a geared-bike or fixie/single-speed?

The reason I ask is if the bike has track-ends (ie "rear-entry dropouts"), then there's a good chance the bike will also have the narrower 120mm or even 110mm dropout spacing (meaning the width between the dropouts). If it's going to be a FG/SS, then there should be no problem, since that fits the width for track-type hubs.

But standard road spacing is 130mm (or 135mm for MTB), which would be too wide to fit. You wouldn't be able to run a standard 8/9-speed cassette/hub without stretching the the rear triangle. (But why do that with a new bike? Just buy a bike with the proper spacing).

--Tim Kleienrt
CerveloDougSloan
Sep 30, 2002 10:19 AM
My Cervelo P3 and Bianchi Pista have rear opening, but for different reasons.

The Pista is a fixed gear bike, and you can better adjust chain tension with horizontal dropouts.

The Cervelo uses horizontal so you can adjust the tire to be as close as possible to the curved down tube for aerodynamics (and also to use as a track bike, if you want).

Rear opening are not as convenient to change wheels; I have not figured out how to do it on the Cervelo without having to grab the chain and pull it out of the way.

Adjustment is best done with the little screws inside the dropouts; once they are set, then the wheel always goes in the same place, and will not yank forward.

Unless you are using the bike with horizontal dropouts for fixed gear or for optimal aerodynamics, I'd avoid it, due to the inconvenience.

Doug
Unless you have front opening Horz. drops. nmEager Beagle
Oct 1, 2002 7:52 AM
semi-horizontal?DougSloan
Oct 1, 2002 9:07 AM
If the rear dropouts were front opening, horizontal, wouldn't the tire hit the seat tube or bottom bracket area when trying to remove the wheel, that is, unless the chain stays are really long. I think semi-horizontal allows the axle to drop down a bit to clear the bottom bracket area on the way out.

Doug
The Klein possibilitythejerseydevil
Sep 30, 2002 1:38 PM
If the frame in question is a Klein, most of what others have posted about rear entry drops doesn't apply since there is no room to adjust the wheelbase.

There is no technical difference with regard to the drivetrain(although according to klein, the wheel is more secure in the drops).

Flats are slightly more tricky to deal with at first, but once you learn how the wheel pops out past the derailleur, it is just as fast as horizontal drops.
The Klein possibilityomar
Oct 1, 2002 5:11 AM
Should've mentioned it in the first place. Frame is a 2002 blade, but I believe your comments are still applicable. It will run a shimano 9-spd cassette, 700 deep rim/tri-spoke rear.