# Bicycle Mechanics - 126mm hub w/ 5 spd in 120mm frame (is this okay?)

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.

pstake
09-30-12, 01:43 PM
I've been running a specialized sealed 126mm hub in my 75 Raleigh Grand Prix frame. This is my beater bike and the wheels are the most valuable thing on it, but I had them and they were not in use. My goal has been to maintain this bike without buying parts (except chains).

So, to do this, I mounted a 5 speed freewheel that I had available, and I'm running miss-matched friction shifters on the downtube.

My question is: Am I doing long-term damage to my hub by running the 126 spacing in a 120 frame? Does the 5 speed freewheel instead of 6 speed, matter?

fietsbob
09-30-12, 01:50 PM
You can reduce the over lock-nut width of the wheel, modify it.
or spread the frame wider , and still mod the hub and go up to #6 standard space.

or #7 a narrower space.. freewheel..

fixing a flat + having a struggle fitting the wheel back in is a PIA,
when the frame has to be pried apart, as well ..

frame is likely well over 35 years old so is already lucky to survive un-damaged this long ..

non parallel dropouts do cause an added stress on the axle and
may add to other stresses , and axle may break, but the axle can be replaced.

'speeds' is just how many cogs are there... It's the Ratio,
in combination with the chainrings that matter.

so count teeth numbers and do some math
to divide front by rear tooth numbers.
like 52)14 = 3.71428.. or 3.714:1

pstake
09-30-12, 01:53 PM
If I change the spacing, e.g. the over lock-nut width, wouldn't I need to re-dish?

You can reduce the over lock-nut width of the wheel, modify it.
or spread the frame wider , and still mod the hub and go up to #6 standard space.

or #7 a narrower space.. freewheel..

fixing a flat + having a struggle fitting the wheel back in is a PIA,
when the frame has to be pried apart, as well ..

frame is likely over 20 years old so is already lucky to survive un-damaged this long

veggie
09-30-12, 02:50 PM
Just cold set the frame. It's steel and only 6mm. Then realign your dropouts if they need it.

Kimmo
09-30-12, 02:52 PM
I'd spread the frame and tweak the dropouts.

Or at the very least tweak the dropouts so they're parallel when you jam the wheel in. Which will make it slightly harder to jam the wheel in, but meh

pstake
09-30-12, 02:56 PM
Just cold set the frame. It's steel and only 6mm. Then realign your dropouts if they need it.

How can I tell if the dropouts need realigned? I realize they need to be parallel but is there a trick to it? Just use a square?

Thanks for the advice ... I don't mind cold-setting. It's a tough frame.

Homebrew01
09-30-12, 02:58 PM
If I change the spacing, e.g. the over lock-nut width, wouldn't I need to re-dish?

Not if you reduce the same amount on each end of the axle. But you may have to cut the axle down too.

Kimmo
09-30-12, 03:04 PM
How can I tell if the dropouts need realigned? I realize they need to be parallel but is there a trick to it? Just use a square?
I use a big ole adjustable wrench and guess. It's like a couple of degrees or so; tweak it a little and it'll be happier.

I guess if you had a spare axle, you could clamp some bits onto it with locknuts to magnify any bend that showed when you clamped it in the frame...

veggie
09-30-12, 03:11 PM
This tool can be used, but if you know how it works I'm sure you could make your own. I have access to one because my dad use to own a bike shop and it is one of the tools he kept

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/1973%20Super%20Sport%20CJ809208/DropoutAlignmentwithParkFFG-2.jpg
http://www.bikeman.com/store/graphics/00000001/Alt-imageB/TL/TL7035B.jpg

mike6024
09-30-12, 03:22 PM
...adjustable wrench and guess. It's like a couple of degrees or so
...

A couple degrees? I figure 6mm is about a quarter inch. So each side is being moved out only one eighth inch. And the chainstay is 15 inches long. So arctangent ( .125/15) = 0.5 degrees. Only one half of one degree.

mrrabbit
09-30-12, 03:23 PM
Ride as is - but have the dropout alignments checked...

OR

Cold spread to 126mm and then check dropout alignments again...

...and yes, changing hub spacing will require re-dishing. Trying to wing it by removing even amounts may result in:

1. Possible chain line disturbance - or making poor chain line even worse. (In your case however you may end up making it better...)
2. Chain clearance issues with the seat stay while in the lowest cog. (Kinda doubt it though with a 5-speed on 6/7 freewheel spaced hub...)

If you are going to modify the hub for classic 120mm and 5-speed spacing:

A = Freewheel stop to end of drive side lock nut.

You want A = 29.00 Get this part right.

C = Outside lock nut to outside lock nut.

You want C = 120.00 - 122.00 Use the non-drive side to finish this spec - doesn't have to be perfect.

=8-)

=8-)

Kimmo
09-30-12, 03:49 PM
A couple degrees? I figure 6mm is about a quarter inch. So each side is being moved out only one eighth inch. And the chainstay is 15 inches long. So arctangent ( .125/15) = 0.5 degrees. Only one half of one degree.

Trigonometry's a fine thing ;)

But I'd say my guess of how many degrees we're talking is a lot worse than how I'd eye it up.

JohnDThompson
09-30-12, 06:26 PM
How can I tell if the dropouts need realigned? I realize they need to be parallel but is there a trick to it? Just use a square?

Thanks for the advice ... I don't mind cold-setting. It's a tough frame.

The best way is to bring the frame to your LBS and let them use their dropout alignment tools (http://www.parktool.com/blog/repair-help/dropout-alignment-ffg-2):

http://www.bikeman.com/images/stories/NameTool/nametool5B.jpg

pstake
09-30-12, 10:08 PM
If the dropouts are not parallel, they are close enough that I can't readily perceive it by looking.

So is a .5-degree change enough to damage my hubs?

It's not terribly difficult to get the wheel in and out. I've put 130 hubs in 126 frames before, which required more effort.

A couple degrees? I figure 6mm is about a quarter inch. So each side is being moved out only one eighth inch. And the chainstay is 15 inches long. So arctangent ( .125/15) = 0.5 degrees. Only one half of one degree.

RaleighSport
09-30-12, 10:15 PM
:innocent::innocent::innocent: I wouldn't recommend it... but I've dropped a 130 wheel in a frame to cold set it o 126...

mike6024
10-01-12, 01:18 AM
If the dropouts are not parallel, they are close enough that I can't readily perceive it by looking.

Yes, a half of one degree is just about nothing as far as I'm concerned. I have no bike mechanic credentials. You would not even consider just trying to bend it with wrench to correct it because you would bend it too far in the other direction. Cannot perceive it in the first place as you noted. Uneven paint thickness on the dropout probably would cause more than a half degree. Doubt a shop could guarantee accuracy of alignment of less than half a degree with special tolls, but you could ask them because I really don't know.

BTW I have done just what you have done with no problem. Had a 15 speed Univega with 120mm and 5 speed freewheel. Hub was cracking around spoke holes. Bought a new hubs (Campy!) to build myself new set of wheels. Didn't even realize it was longer (126mm) till after I bought them as I was not very aware of those type issues being new to working on bikes. Just have to pull a bit every time I have to put the wheel back on after changing a flat. No big deal.

I removed 3mm spacers from the freewheel side and added those 3mm to the other side. You can cut the spacers on the freewheel side if you are going to use a 5 speed on a 126mm hub because those are meant for 6 speed freewheels. Better thing to have done would have been to remove those 3mm from the freewheel side and NOT add them to the other side, and instead cut 3mm off the axle, then you would have a 123mm hub, so you would be spreading the chainstays almost not at all. I think that's what I would have done if I had been thinking more clearly.

mrrabbit
10-01-12, 01:41 AM
Yes, a half of one degree is just about nothing as far as I'm concerned. I have no bike mechanic credentials. You would not even consider just trying to bend it with wrench to correct it because you would bend it too far in the other direction. Cannot perceive it in the first place as you noted. Uneven paint thickness on the dropout probably would cause more than a half degree. Doubt a shop could guarantee accuracy of alignment of less than half a degree with special tolls, but you could ask them because I really don't know.

BTW I have done just what you have done with no problem. Had a 15 speed Univega with 120mm and 5 speed freewheel. Hub was cracking around spoke holes. Bought a new hubs (Campy!) to build myself new set of wheels. Didn't even realize it was longer (126mm) till after I bought them as I was not very aware of those type issues being new to working on bikes. Just have to pull a bit every time I have to put the wheel back on after changing a flat. No big deal.

I removed 3mm spacers from the freewheel side and added those 3mm to the other side. You can cut the spacers on the freewheel side if you are going to use a 5 speed on a 126mm hub because those are meant for 6 speed freewheels. Better thing to have done would have been to remove those 3mm from the freewheel side and NOT add them to the other side, and instead cut 3mm off the axle, then you would have a 123mm hub, so you would be spreading the chainstays almost not at all. I think that's what I would have done if I had been thinking more clearly.

See post #11

=8-)

mike6024
10-01-12, 01:56 AM
From post #11
"If you are going to modify the hub for classic 120mm and 5-speed spacing:

A = Freewheel stop to end of drive side lock nut.

You want A = 29.00 Get this part right.

C = Outside lock nut to outside lock nut.

You want C = 120.00 - 122.00 Use the non-drive side to finish this spec - doesn't have to be perfect."

Well I think I have built about 4 wheels total in my lifetime thus far so you have built about 3000 more than I at his point.

My distance A probably is about 29.00 as you suggest but I would have to take the freewheel off to check it.

"Freewheel stop to end of drive side lock nut" is what I set to be equal to what the original hub I was replacing was, and i did that, best as I recall, by removing 3mm, so it might just be that I ended up with 29mm but it has been a while. I did not set it to 29, but I set it to be about what the original hub was, which, based on your comments, probably was about 29 being an original 120mm 5 speed.

Removing spacers from the drive side reduces dish and makes for a stronger wheel. Adding to the left does the same thing.

Kimmo
10-01-12, 02:20 AM
Yes, a half of one degree is just about nothing as far as I'm concerned. I have no bike mechanic credentials. You would not even consider just trying to bend it with wrench to correct it because you would bend it too far in the other direction. Cannot perceive it in the first place as you noted. Uneven paint thickness on the dropout probably would cause more than a half degree. Doubt a shop could guarantee accuracy of alignment of less than half a degree with special tolls, but you could ask them because I really don't know.

IMO all of that is wrong. 0.5° is more than you might imagine:
http://i.imgur.com/zUE34.png
I can tweak that straighter by eye.

And the paint doesn't matter a damn because the knurling on locknuts bites right through it.

pstake
10-01-12, 08:31 AM
Re: having the dropout alignments checked ...

Does it sound bad to say that I don't trust any of the local bike shops to do this?

They seem usually more interested in telling me what's wrong with riding old bikes than in selling me parts or tools. Makes me a little paranoid that they won't do the simple repair (align dropouts, that I request)

See post #11

=8-)

Kimmo
10-01-12, 10:10 AM
Lots of shop guys are just arrogant ****** who are only interested in parting you from your cash, sad to say... oh, and fraudulently posing as experts.

You'll know a cool shop and a real expert when you find one pretty quick, if you walk in with an interesting old bike.

mike6024
10-01-12, 10:32 AM
You are being advised to make a big deal out of nothing. The quick release skewer puts the whole axle into compression. That is one of the main features of a hollow axle compare to a solid one. Tighten the skewer more if you are concerned. Tightening the skewer effectively strengthens the axle. Of course shops don't want to waste their time on nonsense like this. I have no axle problem as far a I know, doing the same thing you are and using the bike for many years. I would expect a bent axle if I got one to come from carrying weight on the rack and hitting sharp bumps in the road, not dropouts causing it.

pstake
10-01-12, 10:38 AM
Thanks, Mike.

I'm not so worried about breaking an axle. I am more worried that uneven pressure is being exerted on the cartridge bearings, causing them to wear out faster. I'm no engineer but it seems like it wouldn't take much unevenness to affect the bearings.

I think that, by nature of the design, cup and cone hubs would give more leeway in this situation.

Again, I'm not an engineer, so I'm just guessing. And I intend to keep these wheels, or at least the hubs, for a good long while ... so I don't want to trash them by being careless.

You are being advised to make a big deal out of nothing. The quick release skewer puts the whole axle into compression. That is one of the main features of a hollow axle compare to a solid one. Tighten the skewer more if you are concerned. Tightening the skewer effectively strengthens the axle. Of course shops don't want to waste their time on nonsense like this. I have no axle problem as far a I know, doing the same thing you are and using the bike for many years. I would expect a bent axle if I got one to come from carrying weight on the rack and hitting sharp bumps in the road, not dropouts causing it.

Kimmo
10-01-12, 10:43 AM
I'm no engineer but it seems like it wouldn't take much unevenness to affect the bearings.

I think that, by nature of the design, cup and cone hubs would give more leeway in this situation.

This is why I think it's worth the minimal effort to sort it; even cup and cone bearings require precision to maximise durability. I've seen plenty of cones with an uneven groove worn into them from just this.

I wouldn't call one little tweak, once, to ensure it works as designed, a big deal.

pstake
10-01-12, 10:51 AM
Well ... it's a 1975 Nottingham (read: Raleigh proprietary) Grand Prix, with SR cotterless cranks, power-shifter on the right downtube, Lepree friction on the left, modern 105 front der, 300 ex rear der, cyclops brakes with homemade drop bolts and 700c wheels, and a knockoff brooks pleather saddle. All in blue, with a matching blue blackburn rear rack. (freewheel and rear der have been changed since this pic was taken; springs in the rear der were just too worn out)

But maybe it's not an interesting old bike?275869

Lots of shop guys are just arrogant ****** who are only interested in parting you from your cash, sad to say... oh, and fraudulently posing as experts.

You'll know a cool shop and a real expert when you find one pretty quick, if you walk in with an interesting old bike.

Kimmo
10-01-12, 10:56 AM
Nope, it's interesting, all right.

If you turned up in a shop where they were more interested in bikes than money, the first thing someone would do is scope out your ride and notice all the weirdness. You'd earn a smile and a friendly chat and some kudos for all the customisation.

It's not 'hey, wow'... but it is, 'hey, cool'... a 'meh' is not a good sign.

mike6024
10-01-12, 11:04 AM
Take the wheel out. Put a piece of 3/8 inch threaded rod in the place of the axle. With two nuts on it. then turn the nuts so they move outward away from each other until you get 126mm of spread between the dropouts, measuring with a caliper. then you can put two straight edges like steel rulers with one on each dropout face and see that way to what extent they are not parallel. You are magnifying the misalignment this way assuming you can get straight edges flat on the faces. maybe you could use clamps to hold it. if you can get something like this set up, measure the distance between the straight edges near the dropouts, and again out near the ends, and see how different it is.

maybe you could use the rod and nuts to over stretch it and permanently bend it wider so it doesn't spring back to 120mm when you take the wheel out. Problem is you want the two chainstays to bend out an equal amount, 3mm each, and there is no reason to think that doing that would bend them equally. Probably only one would bend because it was weaker.

So why don't you want to remove some spacers and cut the axle, anyway?

Kimmo
10-01-12, 11:07 AM

http://sheldonbrown.com/frame-spacing.html

http://sheldonbrown.com/forkend-alignment.html

pstake
10-01-12, 11:10 AM
So why don't you want to remove some spacers and cut the axle, anyway?

Then I would have to re-dish and that's more of a job than spreading the frame, it seems. And I'm less comfortable re-dishing ... and I want to be able to use the wheels later on a 126 frame.

Kimmo
10-01-12, 11:23 AM
I'd re-dish for a wider OLD, but not for a narrower one unless the frame can't be tweaked (ally, carbon). The wider the OLD, the stronger the wheel.

Dishing is pretty easy; you just add or remove tension from the NDS evenly as necessary... if you can true a wheel, you can dish one.

Incidentally, if you had an old aluminium or carbon frame with a 126mm OLD, you can have a 8/9/10spd wheel with less dish than a normal 130mm OLD one, if you use an off-centre rim.

mrrabbit
10-01-12, 11:29 AM
Take the wheel out. Put a piece of 3/8 inch threaded rod in the place of the axle. With two nuts on it. then turn the nuts so they move outward away from each other until you get 126mm of spread between the dropouts, measuring with a caliper. then you can put two straight edges like steel rulers with one on each dropout face and see that way to what extent they are not parallel. You are magnifying the misalignment this way assuming you can get straight edges flat on the faces. maybe you could use clamps to hold it. if you can get something like this set up, measure the distance between the straight edges near the dropouts, and again out near the ends, and see how different it is.

maybe you could use the rod and nuts to over stretch it and permanently bend it wider so it doesn't spring back to 120mm when you take the wheel out. Problem is you want the two chainstays to bend out an equal amount, 3mm each, and there is no reason to think that doing that would bend them equally. Probably only one would bend because it was weaker.

So why don't you want to remove some spacers and cut the axle, anyway?

And how exactly are you ensuring the spread is even and symmetrically exercised from the center line of the frame?

=8-)

mike6024
10-01-12, 11:39 AM

When Sheldon says how to spread the chainstays he does not mention a need to re-bend the dropouts to be parallel, as far as I see. Does Sheldon consider that insignificant?

Yes he bends each chainstay separately, so you would be bending each 3mm. Then check it with the string so each are equally spread relative to the seat tube.

I say just leave it as is. Only have to pull a bit when mounting the wheel.

Kimmo
10-01-12, 11:46 AM
When Sheldon says how to spread the chainstays he does not mention a need to re-bend the dropouts to be parallel, as far as I see.

He calls em forkends. It was the second link you edited from my post when you quoted it.

http://i.imgur.com/nja81.png

mike6024
10-01-12, 12:07 PM
That cut axle alignment "tool" does not look to be very accurate. It would be difficult to get better than 1/2 degree with that and the crescent wrench as described. Not worth the trouble if what you are looking to correct is so small. At least IMO.

If you could clamp two long straight edges to the dropouts I think you could see a half degree misalignment easier because it would be magnified more.

Kimmo
10-01-12, 12:17 PM
0.5°
http://i.imgur.com/zUE34.png
That's about a mm at that length.

10-01-12, 12:37 PM
pstake, Honestly I wouldn't worry. There is much more clamping force from the QRs than the frame is delivering to the hub on it's own. The dropouts won't have changed angle enough to do any damage. If the tire is centered, keep on riding.

Kimmo
10-01-12, 12:45 PM
There is much more clamping force from the QRs than the frame is delivering to the hub on it's own.

That's totally beside the point.

The two issues here are, 1 - the hassle of jamming the wheel in every time,

And 2 - the non-parallel dropouts are forcing the spindle to bend when it's clamped in, causing premature and excessive wear on the bearings, particularly because they're cartridge type.

mike6024
10-01-12, 01:38 PM
I don't like the idea of spreading the dropouts with a 2 by 4 either. You are bending them separately, yes that is good. But what if you pull too hard and get 5mm? You only need 3mm per each side. If you don't pull hard enough on the 2 by 4 you get no bend at all and it just springs back to the original position.

Seems you could easily overshoot and screw it up. Because all you are looking for is 3mm and that is a small amount, and I would think difficult to do accurately.

Kimmo
10-01-12, 01:48 PM
The OP seems to think it'll be easier than dishing a wheel.

I'd put them about on par. Competence required.

pstake
10-01-12, 04:26 PM
Point taken. Maybe it's time for me to learn to re-dish.

I'd like to learn to spread the frame, too.

Either way, probably won't have a chance to do either until later this week and will try to document my progress and post pictures.

The OP seems to think it'll be easier than dishing a wheel.

I'd put them about on par. Competence required.

Kimmo
10-01-12, 04:30 PM
Like I said, it makes more sense IMO to spread the frame to accommodate a stronger wheel.

Just saying, both jobs require patience and attention to detail.

pstake
10-01-12, 04:35 PM
Ya, plus — spreading the frame makes more sense because most of the wheels available nowadays are 126 - 135.

Like I said, it makes more sense IMO to spread the frame to accommodate a stronger wheel.

Just saying, both jobs require patience and attention to detail.

Kimmo
10-01-12, 04:43 PM
That too, but it's not much of a consideration for a lot of folks with old bikes; a new wheelset is usually quite an occasion.

pstake
10-02-12, 08:36 AM
That too, but it's not much of a consideration for a lot of folks with old bikes; a new wheelset is usually quite an occasion.

I'm pretty active with our local bike co-op and found a guy with a dropout alignment tool, who I'm bringing my bike to Thursday. Good news. I still plan to spread the frame myself, using an all thread.

pstake
10-10-12, 07:04 PM
I just wanted to check back in here. I used a 3/8 all thread and corresponding nuts (four but two would have worked) in the configuration in this photo I took (ignore the mess please — thanks) ... and spread the frame from 120 to a little over 129. I went ahead and went over the 126 mark in case my next set of wheels is a set of 130mm. The frame stretched to about 150 before it started to "bend" permanently.

Then I took the frame to a local guy who has the tool and he aligned the rear dropouts as well as the fork, for \$8. So all in all I spent about \$12 to spread the frame and align the dropouts. The bike rides good and wheel slips in and out like butta.

Thanks to everyone who contributed to this thread and I hope this can help anyone else who stumbles upon it in the future.

Cheers,
Phil

mike6024
10-10-12, 07:44 PM
Congratulations on what you accomplished so far. Glad you are happy!