Convert screw on gearing to road gearing.

[iendicott]

Hi all,

I am attempting to build my own wheels but need some advice. I currently have a 7 speed mega range gear block on my hybrid and I am constantly snapping the QR axel on the rear wheel. I have isolated the issue down to the rear wheel setup.

My proposal is to by a 7 speed road hub and build \ Rebuild this instead of the screw on hub. Is this possible ?

I can calculate the spoke lenghts etc but not sure that replacing \ rebuilding this is possible as the road hubs as far as I can see are slid on gears and the mega range hub is a screw onto the rear wheel.

Thanks Ivan

 

[Scilly Suffolk]

If I've understood you correctly, then the answer is "no".

If the gear cluster is screw-on then it is a "freewheel" which fits on a "freewheel hub". If it slides onto splines and is secured with a lockring, it is a "cassette" which goes onto a "freehub".

The difference between the two, is the location of the clutch which allows the wheel to turn when the pedals aren't: in the former example (which you have), it is contained in the cluster. In the other, it is contained in the wheel's hub.

You can't mix and match as you would (assuming you could get them to fit) either have two clutches or none.

The cassette & freehub is the more modern of the two set-ups; the freewheel & freehub is generally only found on "budget" bikes/bikes with fewer than seven gears.

The problem you describe with the axle snapping is one of the flaws of the freewheel/freehub design and why a different system was needed.

You need both a wheel with a freehub and a new cassette. It is likely that the new hub will also take eight or maybe nine gears, so you may be able to upgrade at the same time; you would need to check the rear derailleur has the capacity, possibly a narrower chain and if you have indexed gears it may be more trouble than it is worth.

 

[RecordAceFromNew]

Hi all,

I am attempting to build my own wheels but need some advice. I currently have a 7 speed mega range gear block on my hybrid and I am constantly snapping the QR axel on the rear wheel. I have isolated the issue down to the rear wheel setup.

My proposal is to by a 7 speed road hub and build \ Rebuild this instead of the screw on hub. Is this possible ?

I can calculate the spoke lenghts etc but not sure that replacing \ rebuilding this is possible as the road hubs as far as I can see are slid on gears and the mega range hub is a screw onto the rear wheel.

Thanks Ivan

I think it is really admirable that you want to rebuild your wheels yourself!

The first step you might want to do is to identify exactly what rear hub your frame needs. It is clear that it is a freewheel, not cassette freehub, but I wonder what the over-locknut-distnace is. It could be a mtb hub (many hybrids have such, with 135mm OLD), and if a road hub whether it is 126mm or 130mm.

Secondly you said you have a 7 speed megarange freewheel. If it is this one with a 11T small cog in good condition then since it is exceptional but no longer made it could be worth secondhand more than a new 7 speed cassette. It might be worth thinking about converting to a freehub cassette system, possibly sticking with 7 speed to avoid complications, if only because the hub choice is far wider.

But the first step is to figure out what hub would fit the frame.

 

[iendicott]

Hi Guys,

Thanks for the replys.

Jimmy, I understand that you can't mix and match but I wanted to replace the Freewheel with a Freehub then add on the gears to match the 7. I suspect I would need a spacer if it where an 8 or 9 speed hub then restrict the derailer to not swing onto the spacer thus keeping it 7 speed mechanically if that makes sense.

RecordAce, So as long the hub is the same width to between the frame as the Freewheel then I should be able to rebuild the wheel with a freehub replacing the freewheel then by the sounds of it ?

Thanks again guys, keep it coming.

Just for the record I have built myself a wheel truing stand and dishing tool from Roger Musson's The Professional Guide to Wheelbuilding. This is a great e-book.

BTW the hub itself is one like this

As you can see the right hand portion of the hub had an extended axel which puts extra load\strain on the QR axel on that side, it's always the right hand side that goes so by changing this for a freehub design I am hoping to eliminate the problem as the bearings are further out.

Ivan

 

[Scilly Suffolk]

My mistake. No reason you can't have a seven speed cassette, I run one on my Summer bike.

With seven gears being a bit "old hat" these days, you might find the choice and availability of cassettes a little limited but by no means difficult to get hold of. That was my experience from the "road" side, probably a little better from the "mtb/hybrid" point of view.

Which takes you to what RAFN wrote: see the revered Sheldon Brown for clarification.

 

[iendicott]

I suspect this is something along the lines of what I need along with the gear rings themselves.

http://www.sjscycles.co.uk/shimano-...-fhim45d-130mm-36-hole-prod15171/?src=froogle

The Sheldon Brown article explains this as you pointed out. Thanks guys.

 

[Nebulous]

Hmm

I had a megarange 13-34 on my mtb, which I use for commuting. I also snapped the axle and bent the qr skewer. I changed the axle and replaced the chain, but the new chain started skipping, so I got a 14-28 freewheel for about £8. The old axle was built up with a few spacers to give the same sort of appearance to the one you have shown.

One thing I considered was swapping to a solid axle, as that would be stronger?

 

[RecordAceFromNew]

I suspect this is something along the lines of what I need along with the gear rings themselves.

http://www.sjscycles.co.uk/shimano-...-fhim45d-130mm-36-hole-prod15171/?src=froogle

The Sheldon Brown article explains this as you pointed out. Thanks guys.

I am a little curious why that hub. That is a 130mm hub, having the same OLD as all typical, modern, road rear hubs. So IF your frame is designed for a 130m hub, then except in the unlikely event that you also run a roller brake why not just pick one from the myriad of modern road cassette rear hubs, and buy a suitable 7 speed cassette plus a 4.5mm spacer (which costs peanuts)?

Answering Nebulous, imho a solid axle will likely be more robust, but then without the convenience of QR.

 

[iendicott]

Hi AFFN, that was just a buh I picked out at random, but I like the idea of the 10 speed hub with a 4.5mm spacer, thanks for the suggestion. How wide is each cog out of interest ? Am I right in thinking about 1.5 mm based on your spacer size ?

Nebulous - I suspect a solid rear hub will befall the same issues albeit lasting a bit longer. The issue is the lenght of spindle between the right hand side bearing and frame is a large distance thus putting more strain on that side.

 

[Scilly Suffolk]

I am constantly snapping the QR axel on the rear wheel. I have isolated the issue down to the rear wheel setup.

The problem you describe with the axle snapping is one of the flaws of the freewheel/freehub design and why a different system was needed.

One thing I considered was swapping to a solid axle, as that would be stronger?

The issue is the lenght of spindle between the right hand side bearing and frame is a large distance thus putting more strain on that side.

A solid axle might temporarily relieve the symptoms, but won't cure the problem.

 

[iendicott]

Jimmy yep kinda what I was saying. I have measured the frame and it is a 135mm frame drop out so a 10 speed road hub with a spacer will work.

 

[RecordAceFromNew]

How wide is each cog out of interest ? Am I right in thinking about 1.5 mm based on your spacer size ?

More than that. It is because different speed cassettes/freewheels don't have the same spacing. See this.

 

[RecordAceFromNew]

Jimmy yep kinda what I was saying. I have measured the frame and it is a 135mm frame drop out so a 10 speed road hub with a spacer will work.

A mtb rear hub is usually more robust (and the wheel can have less dish). I kind of expected that, very few hybrids, if any, use road hubs.

 

[iendicott]

Cheers RAFN. Will do some more work on this then. All the advice you guys have given is invaluable.

 

[Nebulous]

Thanks guys - I'm always impressed by the knowledge on here. If (when?) my axle goes again, then I'll need to try something different. I was under the impression what happened to me was unusual, but it appears not.