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Hub gears on a horiz-dropout frame?
Not knowing much about hub gears.. is this a feasible idea?
My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding drop-outs or gear hangers). On some mornings if I've got to carry a lot to stuff in the panniers my knees feel like they could make use of some gears now and again. Or sometimes I just get bored with fixed and fancy a change.. Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going) be suitable for a frame with horiz-dropouts? And if I wanted to run fixed a few days a week and geared for other days, would the linkage from the hub to the controls be easily removable so I could just change the wheel over? This site mentions a chain-tensioner, I thought the whole point of a hub gear was the chain length/line remains constant but the internal planetry gears drive the hub at a different rate to the chain http://www.kinetics.org.uk/html/rohloff1.shtml After how many miles will a hub gear require servicing, and how much would it cost (to service)? Many thanks, Duncan |
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#2
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Hub gears on a horiz-dropout frame?
Duncan Smith wrote:
Not knowing much about hub gears.. is this a feasible idea? Probably. Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going) be suitable for a frame with horiz-dropouts? And if I wanted to run fixed a few days a week and geared for other days, would the linkage from the hub to the controls be easily removable so I could just change the wheel over? If you set up a suitable linkage with a cable splitter, I'd guess probably yes (SA are going strong since they were taken over by Sunrace in the wake of the asset-strip that brought them down, and SRAM make gear hubs too). This site mentions a chain-tensioner, I thought the whole point of a hub gear was the chain length/line remains constant but the internal planetry gears drive the hub at a different rate to the chain it's potentially part of the point. But if, for example, you have a non-unified rear suspension it's impossible to keep it constant, so you'll need a tensioner. A Brompton uses a tensioner to stop the chain falling off when folding is another use. But while no tensioner is a nice thing, having one doesn't remove the other advantages like your gears being cack-proof, and the chain line not being laterally warped any time one changes gear. After how many miles will a hub gear require servicing, and how much would it cost (to service)? Don't know. In the 5 or so years I've had my Brom I've done, errrrr, zero minutes maintenance of the hub and it still seems to work okay. Rohloffs have huge distances quoted on them with nothing but an oil change once in a while. Pete. -- Peter Clinch Medical Physics IT Officer Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital Fax 44 1382 640177 Dundee DD1 9SY Scotland UK net http://www.dundee.ac.uk/~pjclinch/ |
#3
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Hub gears on a horiz-dropout frame?
On Nov 6, 11:36 am, Duncan Smith wrote:
Not knowing much about hub gears.. is this a feasible idea? My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding drop-outs or gear hangers). On some mornings if I've got to carry a lot to stuff in the panniers my knees feel like they could make use of some gears now and again. Or sometimes I just get bored with fixed and fancy a change.. Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going) be suitable for a frame with horiz-dropouts? And if I wanted to run fixed a few days a week and geared for other days, would the linkage from the hub to the controls be easily removable so I could just change the wheel over? This site mentions a chain-tensioner, I thought the whole point of a hub gear was the chain length/line remains constant but the internal planetry gears drive the hub at a different rate to the chain http://www.kinetics.org.uk/html/rohloff1.shtml After how many miles will a hub gear require servicing, and how much would it cost (to service)? Many thanks, Duncan To completely avoid answering any of your questions about hub gears (sorry!), an alternative, used by some fixie riders is to get a rear hub which is threaded on both sides - many track/fixie hubs are made this way. On one side, they use a track cog and lockring. On the other, a single speed freewheel, often a couple of teeth smaller than the fixed cog. Normally, they ride the fixed track cog as before. On wet/windy/heavy luggage/tired/"just feel like a change" days, they can reverse the same wheel, and ride the single speed freewheel side. Both gears are carried all the time, so you can change while out on the road. The chain length has to be carefully set so that it works with both cogs of different sizes, but with horizontal dropouts of a decent length, it's normally do-able. This gives them a "get you home" bail-out gear, not fixed and somewhat lower than fixed side, without the expense of the second wheel. Just a suggestion... regards, bookieb. |
#4
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Hub gears on a horiz-dropout frame?
Duncan Smith wrote:
Not knowing much about hub gears.. is this a feasible idea? My fixed frame (Pompino) has horizontal drop-outs (no in-bred sliding drop-outs or gear hangers). On some mornings if I've got to carry a lot to stuff in the panniers my knees feel like they could make use of some gears now and again. Or sometimes I just get bored with fixed and fancy a change.. Would a hub gear like a Rolhoff, Nexus or SA i(f they're still going) be suitable for a frame with horiz-dropouts? Yes it's *normal* to use hub gears with horizontal dropouts. And if I wanted to run fixed a few days a week and geared for other days, would the linkage from the hub to the controls be easily removable so I could just change the wheel over? It's fiddly with Shimano Nexus hubs. I'm not sure about other modern ones. This site mentions a chain-tensioner, I thought the whole point of a hub gear was the chain length/line remains constant but the internal planetry gears drive the hub at a different rate to the chain The chain length remains constant but needs to be exactly right (within a few mm) for tension to be acceptable. Chain length can only be altered in units of a pair of links (1 inch), so you need some method of fine tuning. This can be either with some device or by sliding the wheel back and forth in horizontal droputs until chain tension feels correct. You need some slack to get the wheel in the dropouts anyway. http://www.kinetics.org.uk/html/rohloff1.shtml After how many miles will a hub gear require servicing, and how much would it cost (to service)? Depends on hub. See comments on Nexus hubs in another recent thread. Note that these require 130mm dropouts. ~PB |
#5
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Hub gears on a horiz-dropout frame?
ps.
An under-tensioned chain may come off or just not work properly. An over-tensioned chain will cause excessive friction, drag and wear, and will feel nasty. ~PB |
#6
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Hub gears on a horiz-dropout frame?
pps. Duncan, you should already know all this from your experience with
your fixie. As far as chain length and tension goes, the same things apply with hub gears as they do with fixed ones. So, sorry if I typed far more than necessary! ~PB |
#7
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Hub gears on a horiz-dropout frame?
On Nov 6, 12:21 pm, "Pete Biggs"
p...@pomegranateremovehighlyimpracticalfruitbiggs .tc wrote: pps. Duncan, you should already know all this from your experience with your fixie. As far as chain length and tension goes, the same things apply with hub gears as they do with fixed ones. So, sorry if I typed far more than necessary! ~PB Cool, that's what I'd thought, but the tensioner picture made me doubt myself. So, I can run without the tensioner treating the bike pretty much like a normal fixie. And If can disconnect the cable reasonably easy and tie-wrap it around a chainstay or something - then swapping between the two should be a quick night-before job. Many thanks, Duncan |
#8
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Hub gears on a horiz-dropout frame?
This gives them a "get you home" bail-out gear, not fixed and somewhat lower than fixed side, without the expense of the second wheel. Just a suggestion... Cheers, a good point. Often I'm out with another cog on the flip-side but I've never needed the bail-out option (not even on the 110M fun run) - it's never seemed worth it for just another single gear - plus LeVeL hubs don't do a freewheel yet (and I don't think they ever will... :-( ). A few gears would smooth out the steepest hills and speed up the level sections. It's tempting. Thanks, Duncan |
#9
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Hub gears on a horiz-dropout frame?
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#10
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Hub gears on a horiz-dropout frame?
On Nov 6, 12:01 pm, Peter Clinch wrote:
Duncan Smith wrote: After how many miles will a hub gear require servicing, and how much would it cost (to service)? Don't know. In the 5 or so years I've had my Brom I've done, errrrr, zero minutes maintenance of the hub and it still seems to work okay. In the first SRAM hub on my Brompton one of the bearings disintegrated and dumped bits of metal in the hub which in turn resulted in the inner compression spring getting bent. While I was trying to repair it the sliding pin broke - not sure if this was my ham-fistedness or whether it was the bits of bearing doing something nasty or something else. (The primary symptom of the bearing disintegrating was the bike ending up in "neutral" and unable to change back to any gear without stopping and generally being unable to get the adjustment tension right - actually I think it was bits of metal and the bent inner compression spring preventing the various parts sliding properly inside the hub but it felt like the tension was wrong) In the end it was simpler to buy a new wheel because finding parts was difficult to impossible - the hub is still in the shed waiting for a complete set of bearings and a new sliding pin and compression spring - the gears all look fine - fortunately the broken bits of bearing didn't get into the gears. http://www.woodall.me.uk/hub/img_0110.jpg That was after about 3000 miles - I ride the bike hard - typically 30kph+ when not stopped at lights and often reaching 45-50kph on the downhills (in central London) but I don't ride up/down kerbs or anything else like that. Tim. |
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