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12-06.-2007, 02:18 AM
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#1 |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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upgrading low end bike
I have a low end mountan but, but it has a nice Aluminum frame.
I was just thinking about upgrading some of the components. The first thing I'd like to change is the bottom bracket and the crank assembly. Are bottom brackets interchangeable? Will I be able to take the cheap one out and just put the new one in? Also, will I be able to use the stock chain and cassette pack until I afford to replace those too? Thanks for any help!
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12-06.-2007, 10:43 AM
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#2 |
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Registered User
Join Date: Apr 2004
Location: Perth (Basso), West Australia
Posts: 3,509
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Re: upgrading low end bike
How about a pix of the bike and a close up of the BB and Crank.
 Until then, have read of this: http://www.cyclingforums.com/t363004.html
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Cheers, George. |
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12-06.-2007, 10:52 AM
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#3 | |
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Registered User
Join Date: Apr 2005
Location: Not where I would like to be
Posts: 341
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Re: upgrading low end bike
Quote:
Generally speaking though, it is most likely going to have a 68mm English thread. You can repace it but you will need specific tools for the job (bottom bracket removal tool and crank removal tool) or otherwise get your lbs to do it. Go to Parktools for some instructions - http://www.parktool.com/repair/ You will need to get a bottom bracket which matches the cranks you intend on buying in terms of length and 'spindle' type. These include square taper, octalink and isis. Typical MTB bottom brackets range from 113mm up to 122mm but I'm sure there are others available outside this range. When you start looking for cranks the specifications should state what the compatible bottom bracket required would be. You should probably look at buying a new chain and cassette; especially if you have been riding the bike for some time. However, having said that, you can get away with your current chain and cassette. Are you going to be buying a similar speed chain/cassette (ie 8 speed, 9 speed etc). If you are going from 8 to 9 speed your existing chain will work but will most likely be noisy and could lead to premature wear of the chainrings. You can get away with your existing parts but change them as soon as you can afford. Doing all of this yourself is not hard but you will need some specialised tools. However, it's a very satisfying and rewarding feeling getting your hands dirty from upgrading or repairing your bike yourself. |
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12-06.-2007, 11:22 AM
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#4 | |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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Re: upgrading low end bike
yes, it's cheap. I got it at Toys R Us.
It's and OEM JEEP brand. It has a crank like this: http://www.utahmountainbiking.com/fix/crank2.htm I'm not opposed to spending a few bucks on it. I've seen a few Shimano BB's that run only about $60.00 and and crank chain ring combo for about the same. I'm not opposed to spending that much, but not a whole lot more. The bike itself is only a few months old. I got it to ride with my kids on the weekend, but I got involved "Bike Commute Month" here in Sacramento, I realized I really liked riding to work, and I think I've put a lot more miles on it than it was designed for. Quote:
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12-06.-2007, 12:33 PM
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#5 |
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Registered User
Join Date: Apr 2005
Location: Not where I would like to be
Posts: 341
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Re: upgrading low end bike
Without overcapitalising you could buy an inexpensive square taper bottom bracket such as the Shimano BB-UN26 (about AUD$25) and a Shimano TX-70 or TX-71 crankset (less than AUD$50). The former, I believe is 24-34-42 tooth and the latter 28-38-48 tooth (probably good for commuting).
I'm not familiar with the bike so you might want to verify with your lbs that the components will fit. |
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12-06.-2007, 03:35 PM
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#6 | |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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Re: upgrading low end bike
Thanks for the info.
When I took it apart, there was not much in there. I'm going to take it to the shop and see what they think. There was barely enough grease to assemble the thing. The bearings were pretty dry. No wonder it did not turn very easy. I cleaned all the parts, packed the bearings, and completely flooded the races, bearings and the entire crank cavity with grease. The down side is some of the grease is going to ooz out around the shaft, but I'd rather have that than no grease. Quote:
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12-06.-2007, 05:43 PM
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#7 |
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Registered User
Join Date: Mar 2006
Location: Tokai,CAPE TOWN,SA
Posts: 511
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Re: upgrading low end bike
Greasing and servicing the Bottem bracket will make a world of diference ,the BB'S are prone to picking up dirt and water enters the frame and collects in the BB caity,
So a sealed bearing unit offers a better option.However you can't service or repair these they cost more and if they packup you buy another. My brother chaged to a sealed bb about two years ago on his bottem of the price scale MTB,and has been very happy. I.ve a hollow tech sealed BB arangment on my bike which is specific to the bike and i'm on the third one in three years.
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It’s better to want what you have, than to have what you want. |
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13-06.-2007, 02:01 PM
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#8 |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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Re: upgrading low end bike
Here are a few pictures of the bike:
   
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14-06.-2007, 12:52 PM
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#9 |
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Registered User
Join Date: May 2007
Posts: 91
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Re: upgrading low end bike
Be careful what you spend.
If you are really keen on riding it will be cheaper in the long run to buy a better bike than to upgrade, and if you look for old stock you can save quite a bit off full retail. 2008 models should start to hit the shop floors soon and distributors often try to move old stock at serious discounts. If you are friendly with a bike shop they may be able to let you know what may be coming up. |
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14-06.-2007, 04:11 PM
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#10 | |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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Re: upgrading low end bike
yes, I can see the logic in that. I think I'm done trying to work on this thing.
I have it in good working shape right now, but I'm not sure how much longer it will stay the way it is. Quote:
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15-06.-2007, 01:53 PM
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#11 |
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Registered User
Join Date: Apr 2005
Location: Not where I would like to be
Posts: 341
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Re: upgrading low end bike
Use it until it falls apart. Put aside some of the moeny you save from not catching public transport or in fuel and running costs toward buying a better bike.
If your main thing is commuting then maybe look at buying a bike without suspension. It might feel uncomfortable at first if you're not used to it but you will be better off in terms of speed, power transfer etc. Obviously, this will depend on what type of terrain you commute on. |
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15-06.-2007, 02:14 PM
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#12 | |
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Registered User
Join Date: Jun 2007
Location: Sacramento, CA
Posts: 14
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Re: upgrading low end bike
Quote:
I told my wife I'd like to get to three days a week on the bike. It will save us a lot of gas and money. It's a long commute for me, being old and with health probelms, but I think it will help some of my health problems.
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The best guitar photos on the net! |
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15-06.-2007, 07:30 PM
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#13 | |
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Registered User
Join Date: Apr 2005
Location: Not where I would like to be
Posts: 341
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Re: upgrading low end bike
Quote:
Giant makes pretty good bikes so you won't go wrong there. Start slowly and work up to it; you'll be amazed at how quickly your health can change once you get going. Just remember, it's hard to start with if you haven't been on a bike in a long time. Personally, I had given up smoking a year or so before getting back on the bike after a hiatus of quite a few years. The first three or four weeks I thought my lung would collapse. Now I do a 40km round trip commute up to five days a week (depending on whether my babies let me sleep) and I feel really good. |
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19-06.-2007, 08:02 AM
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#14 |
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Registered User
Join Date: Jun 2006
Posts: 1,113
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Re: upgrading low end bike
That BB should last a while provided you reassembled it grit-free and with the correct clearance. If it craps out you'll like the new ones because the axle and bearings are in a cartridge instead of loose, so you just thread it right in. I believe but am not positive that if you get the right width, the chain line will be in the same place as before. Measure your old BB axle from the end of the square taper part, not the end of the threads.
If that thing has a freewheel style rear wheel, I strongly recommend learning how to adjust bearings and staying on top of the adjustment. Adjustment is critical to cup-and-cone ball bearings and the cheap ones are likely to change when new because they break in a lot. If you keep the BB, headset, and wheels well adjusted, especially at first, the bike should last. I bet that thing has a seven speed freewheel in back. No they are not interchangeable with a modern cassette. The way the sprockets attach to the hub is completely different. The chain is narrower too; plus, you won't find 7-speed cassettes or hubs any more so your index shifters wouldn't work. No big deal. Just keep the bearings snug and clean and ride it till you wear it out. Last edited by garage sale GT : 19-06.-2007 at 08:10 AM. |
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19-06.-2007, 08:13 AM
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#15 |
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Registered User
Join Date: Jun 2006
Posts: 1,113
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Re: upgrading low end bike
Incidentally I think a new crankset would bolt right on provided it was for a square taper bb. I am not sure, though, if it would be the same distance to the right of the frame or if the derailleur could be readjusted to take up the difference.
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