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Old 10-19-10, 06:46 AM   #1
ryfeender
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Horizontal Dropout with Derailleur Hangar, need help with wheel placement.

I'm in the process of putting together a bike and I have a question about the horizontal dropouts I have. It has an attached RD hangar and I was wondering what my wheel placement should be?



This is what it looks like. I'm assuming I should push it all the way towards the front.

Any help would be awesome

Thanks

Neil
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Old 10-19-10, 07:08 AM   #2
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Generally just behind the derailluer pivot point. That is where it was in this frame you can see the marks on the drop out where the wheel was tightened previously. Roger
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Old 10-19-10, 07:32 AM   #3
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Most bikes I have seen have the axle in front of the pivot point. I think the way it is should be fine. The existing marks could have been from a fixed/SS build.
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Old 10-19-10, 10:16 AM   #4
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I'd say the axle just goes all the way forward as well. Being slightly ahead of the derailleur pivot is the norm if you look at bikes with vertical dropouts. And the amount of axle lead ahead of the derailleur looks darn close to what you would have if it were a vertical dropout.
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Old 10-19-10, 10:24 AM   #5
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Originally Posted by bidaci View Post
Most bikes I have seen have the axle in front of the pivot point. I think the way it is should be fine. The existing marks could have been from a fixed/SS build.
You are exactly correct, this bike was a fixed gear prior to the conversion.

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I'd say the axle just goes all the way forward as well. Being slightly ahead of the derailleur pivot is the norm if you look at bikes with vertical dropouts. And the amount of axle lead ahead of the derailleur looks darn close to what you would have if it were a vertical dropout.
This is exactly what I was thinking as I was putting this stuff together.


Thanks for the info everyone!

Neil
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Old 10-19-10, 10:27 AM   #6
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As you can see, there's a certain amount of debate here, and the truth of the matter is that it really doesn't matter as far as the derailleur is concerned, but there are differences.

Further forward, shortens the wheelbase making for snappier handling, but can adversely affect handling on steep climbs, especially on tall frames, because the rear axle will be forward as compared to the center of gravity. Also farther forward, improves chain wrap which will help prevent skipping on the smaller sprockets as the chain and cassette wear out, maybe buying you a few hundred miles at the end of their lives (this can always be done later.

One consideration may be chainstay clearance. The clearance gets narrower as you approach the bottom bracket, so pushing the wheel forward will reduce tire clearance, which may be a consideration depending on wheel alignment and tire width.

Those are some of the considerations, and you can make your own informed decision. Just remember that you'll need to re-center the wheel every time you remount it.
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Old 10-19-10, 10:36 AM   #7
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Modern racing style road bikes with vertical dropouts have very little clearance between the rear wheel and the seat stay.
Steering trail has much more to do with handling than wheelbase, most older road bikes have more relaxed head tube angles and more trail than modern road bikes. I would bet that this bike has plenty of trail to offset any quicker steering that shortening the wheel base could cause.
I don't see any problem with moving the axle forward. Just be sure the chain is properly sized.

Last edited by Al1943; 10-19-10 at 10:57 AM.
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Old 10-19-10, 10:39 AM   #8
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Originally Posted by FBinNY View Post
Further forward, shortens the wheelbase making for snappier handling, but can adversely affect handling on steep climbs, especially on tall frames, because the rear axle will be forward as compared to the center of gravity.
I've read this claim numerous times from many posters and writers but have always wondered if there is any validity to it. The change in wheelbase from all the way forward to all the way back in most horizontal dropouts is, perhaps, 15 mm or less than 1.5% of a typical 1000 mm wheelbase. Is that enough to make any difference in responsiveness?
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Old 10-19-10, 05:02 PM   #9
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Frame Model

Ryfeeder, what's the name of that frame??

Drew
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Old 10-19-10, 05:11 PM   #10
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I've read this claim numerous times from many posters and writers but have always wondered if there is any validity to it. The change in wheelbase from all the way forward to all the way back in most horizontal dropouts is, perhaps, 15 mm or less than 1.5% of a typical 1000 mm wheelbase. Is that enough to make any difference in responsiveness?
I have never had a bike with long horizontal dropouts to try it with but I can tell you that I definetly notice the difference in handling between mountain bikes in medium and large sizes where the geometry is all the same but the wheelbase is about 2.5 to 3 cm longer for the large size. to me it's almost like night and day. Similarly, with different bikes this time, my old Cannondale touring bike feels positively Chrysler Beaumont'ish compared to my shorter wheebase road bikes with the same "size" frames. Again there's about a 2.5 cm difference in wheelbase. But granted in this case there's also the chance of differing front end geometries.
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Old 10-19-10, 10:05 PM   #11
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Ryfeeder, what's the name of that frame??

Drew
It's a piece of crap Fetish Cycles Freccia
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Old 10-19-10, 10:20 PM   #12
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The best shifting-performance is achieved with the cogs as close to the upper-pulley as possible. Different frame & dropout as well as derailleur designs will vary the position in the actual slots, but as long as you place the cogs as close to the upper-pulley as possible, it will shift best.

As for handling, I've haven't been able to tell the difference with rear-wheel only adjustments. I've noticed that bikes with shorter overall wheelbase tends to handle better.
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Old 10-20-10, 03:29 AM   #13
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I have varied the position of the axle in my horizontal dropouts. You can detect a slight difference in handling due to wheelbase.

BTW those are "track ends" not dropouts.
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Old 10-20-10, 10:12 AM   #14
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IT matters little, try various placements and see your personal preference.

A rear opening fork end is one way to build a short wheel base rear end.

More suitable to be set up as a fixed gear street bike than a vertical rear dropout would be, or a lot better than a Track frame ,

that you kids naively buy, and then want know how to drill a brake hole in a carbon composite track fork for a front brake.
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