Horizontal dropouts and adjustment screws - necessary?

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Horizontal dropouts and adjustment screws - necessary?

Postby DavidH » Fri Feb 29, 2008 10:13 pm

I've been on the lookout for a cheap steel frame to build a new road bike for commuting. I managed to find a Reynolds 653 frame and fork...coloured fluorescent purple :shock: (gotta love the 80s). It's been powder coated white and now looks like this...

Image

and the horizontal dropouts look like this...

Image
Image

On both of my current road bikes I have near-vertical dropouts and when fitting the rear wheel I always ensure that the axle is sitting in the dropouts as far as they will go (which is why I always have the bike on the ground before I tighten the skewer).

What is the deal with horizontal dropouts? On the inside of the dropouts there is clearly a shallow dished out section that looks like it is the intended spot for the wheel axle to be mounted, but if this is the case then it would mean NOT pushing the axle back as far back as it can go. If this is the case then I can see why it would be nice to have the adjustment screws fitted to the dropouts (although they weren't on the frame when I bought it).

Oh, and this will eventually be a geared bike (not fixed/single speed).

How do you determine the correct placement of the rear wheel axle in horizontal dropouts?
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by BNA » Fri Feb 29, 2008 10:23 pm

BNA
 

Postby Kalgrm » Fri Feb 29, 2008 10:23 pm

When I had a bike with that sort of drop-outs, I always used the brake blocks as my guide to wheel placement. Someone else might have a better idea though.

Cheers,
Graeme

(PS - nice work on the paint. Looks very clean.)
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Postby Kid_Carbine » Sat Mar 01, 2008 12:24 am

The way I remember it, the term 'horizontal dropouts' refered to the rear facing fork ends that are normally seen with fixed wheel & single speed freewheel bikes.
What you have was always known to me as 'road dropouts'. The axle is not supposed to be pushed all the way back, instead there is supposed to be an adjustable screw, with a spring, that is inserted from the inside of the axle slot on each side. This allows you to position the sprocket cluster [the freewheel] in the best place in relation to the derailleur that you are using.

These adjustable screws also allow you to correctly align the rear wheel & once set, the wheel goes back into eactly the same spot every time, so I'd say that a trip to the bike shop will eventually be in order. You need six pieces, that being two adjusting screws, two long springs designed to prevent the free rotation of the screw & since the screw emerges from the frame pointing up & back, there is a small round but blind nut, or cap that threads over the end of the screw. Naturally you will need two of these plus any spares you might want to get.

Once the wheel is correctly positioned, you then adjust the position & angle of the brake blocks. When the wheel is refitted after a puncture repair [or other] these brake blocks will line up every time too.
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Postby thomas_cho » Sat Mar 01, 2008 7:44 am

You should be able to purchase the dropout screws from your LBS. I got mine, for $5.

Before I got them I was just eyeballing the rear wheel to make sure it sits centred between the chainstays.

You can also find these rear dropout screws for sale on ebay, the last time I looked there were some Campagnolo dropout screws. They come in different lengths as well.
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Postby DavidH » Sat Mar 01, 2008 7:52 am

Kid_Carbine wrote:The way I remember it, the term 'horizontal dropouts' refered to the rear facing fork ends that are normally seen with fixed wheel & single speed freewheel bikes.

According to Sheldon Brown the rear facing fork ends are not called dropouts at all...he calls them "Track Fork Ends".

http://www.sheldonbrown.com/gloss_dr-z.html#dropout

Kid_Carbine wrote:You need six pieces, that being two adjusting screws, two long springs designed to prevent the free rotation of the screw & since the screw emerges from the frame pointing up & back, there is a small round but blind nut, or cap that threads over the end of the screw. Naturally you will need two of these plus any spares you might want to get.


So the adjustment screw is inserted from the inside of the dropout? In other words, the axle will rest up against the head of the adjustment screw? Now that I think about it that makes perfect sense, but all this time I was picturing the screws being inserted from the back of the frame. In fact, now that I REALLY think about it I had a Reynolds 531 frame about 20 years ago and I can vaguely remember the adjustment screw being setup the way you describe. Now the challenge will be to find a set of adjustment screw (with spring and cap).
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Postby DavidH » Sat Mar 01, 2008 8:29 am

thomas_cho wrote:You should be able to purchase the dropout screws from your LBS. I got mine, for $5.

Before I got them I was just eyeballing the rear wheel to make sure it sits centred between the chainstays.

You can also find these rear dropout screws for sale on ebay, the last time I looked there were some Campagnolo dropout screws. They come in different lengths as well.

OK. Thanks for that. For some reason I thought they would be virtually impossible to find. As a fellow Canberrian, can I ask at which LBS you purchased the screws from?
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