Bicycle Mechanics - Repair or discard?
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08-18-11, 09:38 AM
Would you just discard low end rear wheel that has had several broken spokes and just broke two more, or would you get a handful of spokes set to twisting and tightening? ie, would you consider cheap wheels to be disposable consumables? I'm inclined to discard because I doubt I'll ever get it really true, and the time involved if I did might be more than the wheel is worth, but if that's the best option ...
Is something like this http://www.amazon.com/WHEEL-MASTER-WEINMANN-RELEASE-7-SPEED/dp/B000AO3GES/ref=pd_sbs_sg_3 feasible or is a better quality advisable? Is there a way to tell from this add or the pictures what the hub width is? I need 130mm.
Would it be a horrible mistake to replace a wheel and 7-speed freewheel with one with 8-speed cassette without replacing the shifter? Would it lose or skip one gear or would all the gears be off by n/7?
08-18-11, 09:49 AM
If the wheel has broken several spokes, it's safe to assume the rest aren't much better off. Assuming the rim is still in good condition, just replacing all of the spokes and having the wheel rebuilt properly would cost way more than the replacement wheel you referenced. Get a new wheel. The referenced wheel is probably servicable but should be trued and tensioned by a competent wheel builder before it's used or you will have the same early failure as your present wheel.
How much further upscale you should go depends on the bike and your usage. If you ride a fair bit and your bike is important to you, I'd go for a much better wheel. I'm not certain about this but i believe 7 and 8-speed Shimano cassettes are similarly spaced so 7-speed shifters will shift an 8-speed cassette adequately and some 7-speed shifters have enough overtravel to let you use all 8. Someone else who has actually done this can comment better.
08-18-11, 11:23 AM
I replaced a rear wheel and went from a 7-speed freewheel to an 8-speed cassette. The bike had a SRAM grip shifter. The 7-speed grip shift worked OK, but I couldn't shift into the smallest cog, the shifter wouldn't go far enough past 7. I never liked the grip shift anyway and replaced it with trigger shifters. I found inexpensive 8-speed SRAM ESP shifters at REI. The cassette design is better anyway, the drive side bearings are further outboard on the wheel and should last longer. The reason I replaced the rear wheel is it was a cheap wheel and the bearings were going out on the drive side.
08-20-11, 11:17 AM
Thanks for the information. I wound up ordering a somewhat better low end wheel (Mach1 since I'm satisfied with the matching front wheel) and the shimano 7-speed cassette with a spacer. Keeping my fingers crossed that it all matches up.:twitchy:
My limit on spoke replacement over the life of a wheel is three, if they're well spaced out over time, otherwise I start fresh sooner than that. If you have that many problems, and the wheel is low end in the first place (maybe that's why it doesn't hold up) there's no use prolonging the agony.
Now the question is is the hub worth enough to reuse, or is it smarter to buy a new wheel which is usually less costly than a rebuild (depending on the hub). All my hubs are top end, so I always reuse them, plus since I build my own, there's no labor cost to factor in.
Run the numbers, but whatever you don't spend lots of time, effort or dough to end up with an expensive low end wheel.
09-03-11, 10:15 AM
Not to bump this but I'm always disappointed to search out how or whether to do something, find a thread like this with no final result. So since I asked here's a summary.
The question was what to do about multiple spokes breaking on a rear wheel which has a 7 speed freewheel. Freewheels come on lower end bicycles or big box bikes, and are generally considered obsolete or disposable. I replaced the wheel with an inexpensive Mach 1 with 8-speed freehub (just match the dropout width and rim width), and ordered a Shimano 7-speed cassette (Hyperglide 30). You need a spacer for a 7 speed cassette on 8 speed hub. It's just a ring to take up space, and widths are standard so Avenir 7Spd Cassette Hub Spacer. Finally a tool to tighten the lock ring to hold it on but all Shimano cassettes need the same tool so just visit the LBS and pick one up. The whole shebang was $60.
This is very easy and worked perfectly, after adjusting derailleurs a little. The only additional replacement needed is likely the chain depending on how worn the cogs were. It's safe to consider it an upgrade over the original.
09-03-11, 10:33 AM
Thanks for the followup. It is nice to know what happened when and if the OP did what was recommended here and what the outcome was. Happy riding.
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