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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 01-04-10, 08:35 PM   #1
S2landie
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some tech questions on a fixed gear build

I am building a fixed gear bike out of a late 70s Concord (Kuwuhara) frame. I am good to go on newer bike hardware but some of this older stuff looks a bit foreign to me.
The spindle on my bottom bracket has square taper fit ends. Is it possible to find a single speed set of crank arms for this type of BB? I'd love to run an older 44 tooth BMX sprocket on this thing. Also, the sprocket on the bike seems as though it's pressed or interference fitted to the drive side crank arm (the sprocket carrier is bent to hell and unusable). Would I be better off going with a new, sealed BB, if this exists? The BB cups thread into the frame and the cranks arms are Sugino.
Aside from that, I was hoping some people on this forum could point me in the right direction for some cool websites/stores for fixed gear parts.
Thanks!

Last edited by S2landie; 01-04-10 at 08:40 PM.
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Old 01-04-10, 09:55 PM   #2
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Yes, on the current BB. Your cranks were cheap, now they're history.
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Old 01-06-10, 08:14 AM   #3
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I figured the cranks would be paper weights. I repacked the BB bearings after cleaning them and they look like they'll hold up. The spindle was in great condition. I've been looking at stuff on the "Eighthinch" website. The Eighthinch cranks look pretty nice/cheap...just wondering about the quality. Also, I read a thread about some knock off wheels that you and a few others tested and liked for the price paid. I'm wondering if these Eighthinch "Tessa" wheels are any better. Another dumb question...the seatpost on this old Concord frame. Any ideas on the size?
Thanks again.
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Old 01-06-10, 08:38 AM   #4
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I've got these Eighthinch cranks, and they're fine for the price. They're really about the same as any OEM crank, but would be perfectly suited to your conversion. The Tessa wheels would definitely be better than the knockoffs, but they also cost a bit more. The knockoffs are a good deal if you want an inexpensive deep aero section wheel. I have no doubt that the Tessa's will perform better.

I keep a digital micrometer handy for measuring posts and clamps, but if it's a steel frame, 27.2 would be my best guess. Take it to a bike shop and have them measure.
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Old 01-06-10, 09:21 AM   #5
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never tried the eighth inch cranks or the tessas. But on ur seatpost diameter, take it to the shop. They'll have those seatpost sizing rods that is kinda like what people use to determine ring sizes.

Sheldon Brown also have a page of seatpost sizes according the the brand/model/year. If u're lucky u can find yours here:
http://www.sheldonbrown.com/seatpost-sizes.html
But I'ld just take it to a bike shop to get it measured.
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Old 01-06-10, 09:50 AM   #6
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You'll be able to answer an awful lot of size questions with one of these:



http://www.harborfreight.com/cpi/cta...emnumber=47257

Or, if your budget is tight, this one will give you a good guess:



http://www.harborfreight.com/cpi/cta...temnumber=7914


I found that Universal Cycles (http://www.universalcycles.com/) has a really amazing selection of oddly sized seat posts. I got this one:



http://www.universalcycles.com/shopp...7&category=623

As for cranksets, the first thing you need to figure out is what you're going to do about chainline. The easiest solution is often to get a new track wheelset, which usually has a 42mm chainline, then get a crankset and bottom bracket to match that. I would guess that any of the cranksets available in the $50 range (Eighth Inch, Origin8, Sugino XD) are probably of similar quality (all decent) and generally give you a 42mm chainline with a 103mm bottom bracket.

You can also use road double cranksets by removing one ring and getting short stack bolts. In general, with the recommend bottom bracket length the inner ring position will be at 41mm, but a carefully chosen shorter than recommended bottom bracket will put the outer chainring around the magic 42mm. This is actually what most of the above crankset are doing.

I got a used pair of Shimano 600 (FC-6400, predecessor of Ultegra) cranks on eBay recently for about $20. I think this will give me a good chainline on the outer ring with a 103mm bottom bracket, and I would guess this will be slightly better than the comparably priced "new" "singlespeed" cranksets.

A few more useful links:

http://www.sheldonbrown.com/fixed.html
http://www.benscycle.net
http://thebikesmiths.com/j/index.php...d=17&Itemid=59
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Old 01-06-10, 09:53 AM   #7
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I have that digital caliper, and it makes working on bikes so much simpler when you have lots of bikes/parts.
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Old 01-06-10, 10:01 AM   #8
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Thanks for the input, everyone. I guess I'll have to contact Eighthinch about the wheels and cranks and see if they will match up regarding offset.
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Old 01-06-10, 10:06 AM   #9
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You'll probably need a 103mm BB, and all will be good. Unless I'm forgetting something.
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Old 01-06-10, 11:29 AM   #10
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and my thread-in BB is an english thread?
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Old 01-06-10, 11:38 AM   #11
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http://harriscyclery.net/product/sug...acket-2140.htm

like this?
then I go over to the eighthinch website and the cranks they sell apparently require a 107 to 110 mm JIS BB????? now my little brain is smoking...

Last edited by S2landie; 01-06-10 at 11:53 AM. Reason: incorrect
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Old 01-06-10, 12:18 PM   #12
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Quote:
Originally Posted by S2landie View Post
http://harriscyclery.net/product/sug...acket-2140.htm

like this?
then I go over to the eighthinch website and the cranks they sell apparently require a 107 to 110 mm JIS BB????? now my little brain is smoking...
http://www.sheldonbrown.com/bbtaper.html

Your cranks need to be compatible with the bottom bracket, with regards to how steep the taper is on the square spindle ends and on the inside of the crank connection point. JIS vs. ISO. Also, your rear cog and the chainring up front need to agree about how far outboard of the centerline of the bike the chain will be, otherwise the chainline will be cocked. So, buy your parts in an order that will allow you to consider these things.
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Old 01-06-10, 01:06 PM   #13
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Ok I'm grasping it now...Thanks.
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Old 01-06-10, 01:10 PM   #14
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Quote:
Originally Posted by ismellfish2 View Post
So, buy your parts in an order that will allow you to consider these things.
BB last.
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