Is there any structural design advantage (e.g. pawls, spacings, bearings etc) in the Shimano 11-34 seven speed Megarange freewheel, compared with the 13-34 and 14-34 Shimano seven speed Megarange freewheels? I'm thinking about putting one of these freewheels on one of our tandems and wanted to choose the best structural design for a heavily laden tandem having had a new Shimano freewheel disintegrate under load in the Alps in years gone by. As the rear hub was custom built and runs beautifully even after 20 years, I'm reluctant to buy a new rear cassette and free-hub.
I've had a look at the Sheldon Brown web-site and can't find the answer to my question. Thanks for your help.
Shimano Megarange 7 speed freewheels
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jimcrosskell
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- Joined: 19 Jan 2007, 6:40pm
Not sure on structural stuff cdtb, we run 11~34 megarange freewheels on both our tandems and we are definately in the pusher rather than the spinner variety of teams. The engineers will no doubt tell us that the more sprockets you have on a freewheel, the gretaer the strain you put on the hub & bearings as opposed to a cassette. The only problem we have had was the rock ring loosening causing the whole thing to wobble. This was easily sorted at the roadside by tightening the lockring without having to remove the wheel.
What rear mech do you run with you current megarange setup? We have just fitted a Deore and it seems an improvement on the Altera thing supplied by Halfords.
Backwinds forever..........
What rear mech do you run with you current megarange setup? We have just fitted a Deore and it seems an improvement on the Altera thing supplied by Halfords.
Backwinds forever..........
jimcrosskell wrote:What rear mech do you run with you current megarange setup? We have just fitted a Deore and it seems an improvement on the Altera thing supplied by Halfords.
thanks Jim
The rear mech is presently a Shimano Nexave 'rapid rise' derailleur but with a Sachs Aris freewheel, and not a Megarange freewheel.
.........the thought of the 34 tooth spocket seems attractive for those hills and my ageing legs, but I was wondering whether there was any design advantage to the newer 11-34 freewheel, compared with the older Shimano 13-34 and 14-34 Megarange freewheels?
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jimcrosskell
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- Joined: 19 Jan 2007, 6:40pm
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NewHorizon
- Posts: 472
- Joined: 14 Mar 2007, 10:10am
- Location: UK
Re: Shimano Megarange 7 speed freewheels
cdtb wrote:Is there any structural design advantage (e.g. pawls, spacings, bearings etc) in the Shimano 11-34 seven speed Megarange freewheel, compared with the 13-34 and 14-34 Shimano seven speed Megarange freewheels? I'm thinking about putting one of these freewheels on one of our tandems and wanted to choose the best structural design for a heavily laden tandem having had a new Shimano freewheel disintegrate under load in the Alps in years gone by. As the rear hub was custom built and runs beautifully even after 20 years, I'm reluctant to buy a new rear cassette and free-hub.
.
I can't answer your question about internal mechanical differences between the 11 and the 13&14. However, I've been using/abusing Shimano 14-34 7 speeds for some years now,sometimes in mud & immersed in water & I've suffered no problems with the internals. Previously, I'd experienced various freewheel failures.
I agree with your reluctance to upgrade to cassette while your present set-up is functioning well.
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MikewsMITH2
- Posts: 1805
- Joined: 19 Sep 2008, 10:25am
- Location: POOLE Dorset
Shimano Megarange
Have recently fitted a mefarange 7 sp 14-34 to our Tandem (after destroying a new freewheel on the first steep hill!) No problems after several long rides. Seems strongly built. 
The Megarange works fine with a Shimano Alivio rear mech, as recommended by my local bike shop, although I have since found out that Shimano do a specific megarange rear mech.
The Megarange works fine with a Shimano Alivio rear mech, as recommended by my local bike shop, although I have since found out that Shimano do a specific megarange rear mech.
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jimcrosskell
- Posts: 87
- Joined: 19 Jan 2007, 6:40pm
Shimano Freewheels
My supergalaxy tandem has just had its 80,000 mile service! (16 years old) over this period we have had numerous freewheel failures mainly eminating from the lock ring coming loose. (All shimano 6 speed 14/28 ) I now now the signs of a loosening lock ring, woolly rear gear shifts and as some posts suggests you can tighten it sufficiently to get you home without removing the wheel using a small screwdriver for instance. Why do tandems seem prone to this problem ? anyone any ideas. I have also had one failure of the internal pawls whereby the freewheel became a fixed wheel for the ride home.
I think the problem is simply one of much bigger forces being put through the thing by two riders instead of one.
Bearing in mind freewheels are really bottom-end stuff these days it's probably that they are costed down to the minimum for usability.
Personally I'd be tempted to go to a freehub, depending on the complexity of whether your frame needs respacing etc. Bombproof Shimano XT ones are around £40.
Bearing in mind freewheels are really bottom-end stuff these days it's probably that they are costed down to the minimum for usability.
Personally I'd be tempted to go to a freehub, depending on the complexity of whether your frame needs respacing etc. Bombproof Shimano XT ones are around £40.
11-34 seven speed Megarange freewheel
They are not.jimcrosskell wrote:does anyone know if the smallest cogs are interchangeable with any othe Shimano freewheel?
Yes, supposedly ...cdtb wrote:Is there any structural design advantage
cdtb wrote:I've had a look at the Sheldon Brown web-site and can't find the answer to my question
For the full story see:
http://www.sheldonbrown.com/mega7/
well done and thanks ddddddd.
I missed the key description on the web-site of the differences between the 11-34 and the 14-34 (and I presume the 13-34 Megarange freewheel).
From Sheldon Brown..........'New Mega 7 11-34 freewheel partially disassembled - the core has large(r) diameter threads that screw into the back of the sprocket carrier. The (back of the core) also acts as a lock ring to hold the 34 tooth sprocket to the carrier'.
From looking at the Sheldon Brown web-site the load bearing pawls look very similar between the different Megarange freewheels, but I imagine the 11-34 freewheel core is less likely to disengage from the back of the sprocket carrier under the extreme load on a fully laden tandem, (because of the more secure, threaded fixing, of the core to the sprocket carrier).
I missed the key description on the web-site of the differences between the 11-34 and the 14-34 (and I presume the 13-34 Megarange freewheel).
From Sheldon Brown..........'New Mega 7 11-34 freewheel partially disassembled - the core has large(r) diameter threads that screw into the back of the sprocket carrier. The (back of the core) also acts as a lock ring to hold the 34 tooth sprocket to the carrier'.
From looking at the Sheldon Brown web-site the load bearing pawls look very similar between the different Megarange freewheels, but I imagine the 11-34 freewheel core is less likely to disengage from the back of the sprocket carrier under the extreme load on a fully laden tandem, (because of the more secure, threaded fixing, of the core to the sprocket carrier).