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Old 05-22-12, 09:58 AM   #1
marthablue
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Will my mechanic think I am crazy?

I have an old late 90's Raleigh M20, I want to convert it to a single speed bike.

I have been researching how to do it but it is a bit overwhelming. It seems like converting a bike is something that looks way easier that it is. I would rather do it myself, I enjoy mechanics, but I am very busy and don't have a ton of time, and I don't want to mess up my bike. Then I wont have a bike at all.

So I am considering taking it in to the local bike shop and asking him (it is a small one man op) to convert it to a single speed.

Will he think I am crazy? Is this something that mechanics even do? And could anyone give me a ballpark idea of how much it is likely to cost? $50? $2,000?
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Old 05-22-12, 10:16 AM   #2
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Single speed or fixed gear ? if you want fixed gear, don't bother with this bike, i don't think it has horizontal dropouts. If you want just a single speed, you can get that done much cheaper and easier. You can even just leave the rear cassette/freewheel in place, and even leave all 3 of the front chainrings in place and just remove the derailleurs and then just fix the chain to whatever front and rear chainring you want to use. I saw that done a couple of times at my coop for people that wanted to try single speed without committing to it.

Single speed means you still can still coast. Fixed gear means the front pedals are locked to the hub in the back, when you pedal, the bike moves. When you stop pedaling the bike stops. you go down a hill, you cannot coast at all, you have to pedal.
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Old 05-22-12, 10:18 AM   #3
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Probably. A bike that new would take a lot of tweaking and special parts to make it a single-speed. I'm sure he'd be happy to take your money, but you would be better off leaving this bike whole and functional, and find an older bike to convert.
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Old 05-22-12, 10:19 AM   #4
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The single best way to do this is to measure your rear dropout spacing
with a cheap vernier caliper from Harbor Freight or the like......



and then order yourself a new wheel in the appropriate diameter
(matching your front wheel size, eg 700c, 26", etc) but with one
of the flip flop hubs that have a fixed cog on one side and a SS
freewheel on the other...........but with the appropriate hub spacing
for your particular dropouts width.

The cheapest way, assuming you don't have the ambition to ride
a fixed gear bike, is to remove the derailleurs, shifters, smaller front
chainring, and current freewheel, put them in a box or bag and save
them, and replace with a single speed freewheel that is spaced to sit
approximately even with your front chainwheel, so you get a straight
chainline. You then must shorten the chain a bit, and if you have
vertical dropouts, as opposed to horizontal, you'll likely have some
issues with properly adjusting chain tension.

It's not all that hard to do, but it may require more mechanical
sophistication and tools than you currently have. I presume you
want to do this for simplicity's sake, otherwise, I can see no valid
reason to go to the trouble. I'm sure you can find someone who'll
do it for you, but I honestly have no idea of what they'll charge.
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Old 05-22-12, 10:22 AM   #5
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Donor bikes should have horizontal dropouts or rear-facing track ends. You can use an expensive eccentric hub (White Industries ENO) to tighten the chain but its not worth the investment.
Spring chain tensioners can be used with SS but not fixed gear. The whole point of SS is to eliminate all that stuff from the bike.
You may be able to find a magic number gear to achieve good chain tension, and maybe use a 1/2-link to get the chain correct but as the chain wears, you cant take up slack.
Have you read this.
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Old 05-22-12, 10:48 AM   #6
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Single speed means you still can still coast. Fixed gear means the front pedals are locked to the hub in the back, when you pedal, the bike moves. When you stop pedaling the bike stops. you go down a hill, you cannot coast at all, you have to pedal.
I definitely do not want a fixed gear bike. I want to be able to coast. Here is a pic of the drop out, don't know if it is horizontal or not, but I guess it is all academic anyways.



Quote:
You can even just leave the rear cassette/freewheel in place, and even leave all 3 of the front chainrings in place and just remove the derailleurs and then just fix the chain to whatever front and rear chainring you want to use. I saw that done a couple of times at my coop for people that wanted to try single speed without committing to it.
I was about to ask if this would work...It seems like the quickest way to just get riding. And that is really my goal here.
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Old 05-22-12, 10:50 AM   #7
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I hadn't read that, thanks for the link. My google-fu found the original from 2001 but not the updated better one that you linked.
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Old 05-22-12, 11:02 AM   #8
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Here is a pic of the drop out, don't know if it is horizontal or not, but I guess it is all academic anyways.

That's semi-horizontal. It'll work. You just need enough front-to-back adjustment to keep the chain tight.

Assuming you have a 7-speed freewheel rear hub, remove the freewheel and replace it with a single speed freewheel. Make sure your new freewheel matches your chain width. Put it on and figure out which of your front chainring positions will give you the straightest chainline. Mount the chainring you plan to use in that position. Resize your chain and you'll be good-to-go.
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Old 05-22-12, 11:05 AM   #9
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I picked up a nice 90s Nishiki MTB and converted to SS for an additional $30 including slicks but it had three features that made it incredibly easy. First, it had semi-horizontal dropouts. Second, the chainrings were bolted and not riveted. Third, it had a freehub vs a freewheel so I didn't need a SS freewheel and then have to respace and redish the rear wheel (which isn't that hard but its more work). All I needed was a cog and spacers for the freehub. If any of these are missing, the cost can go up considerably - especially if you want fixed or flip-flop.

I will say that for a while I used an old RD as a tensioner because the chainrings were Shimano Biopace and oval so tensioning without it was impossible. It was much smoother and quieter than expected and worked well. Then I picked up a ring at a co-op for $1, took off the tensioner, shortened the chain, and its a ss that rides incredibly quiet and efficient.
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Old 05-22-12, 11:06 AM   #10
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I took an old freewheel bike , and with a few axle spacers shuffled
re centered the hub into the axle center. and re tensioned the spokes ..
all I bought, new was the single cog [3/32 wide] freewheel, and chain,

the other way single speed freewheels come , is 1/8" wide.. different chain..
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Old 05-22-12, 11:17 AM   #11
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That's semi-horizontal. It'll work. You just need enough front-to-back adjustment to keep the chain tight.

Assuming you have a 7-speed freewheel rear hub, remove the freewheel and replace it with a single speed freewheel. Make sure your new freewheel matches your chain width. Put it on and figure out which of your front chainring positions will give you the straightest chainline. Mount the chainring you plan to use in that position. Resize your chain and you'll be good-to-go.
This will not work unless the axle is re-spaced and the hub centered by re-dishing the wheel.
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Old 05-22-12, 12:33 PM   #12
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Speed, disregard my earlier post. You'll need to rework the rear wheel (or buy a new one for this purpose), but single-speed is doable here.
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Old 05-22-12, 02:50 PM   #13
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...I will say that for a while I used an old RD as a tensioner because the chainrings were Shimano Biopace and oval so tensioning without it was impossible...
Don't propagate misinformation. Oval Biopace chainrings will work fine in a ss system with horizontal dropouts. The amount of chain wrap doesn't change.
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Old 05-22-12, 03:30 PM   #14
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Don't propagate misinformation. Oval Biopace chainrings will work fine in a ss system with horizontal dropouts. The amount of chain wrap doesn't change.
Are you sure about that? Now you have me curious. When I get home, I think I have one bike that has biopace rings. I am going to watch the rear derailleur and see if it stays put while I spin the pedals backwards. if the rear cage stays put, then I think you are onto something. if the rear cage moves around, then your info is most likely false. Interesting.
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Old 05-22-12, 03:32 PM   #15
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Here's what we'll need to know, and what your mechanic will figure out in about 4 seconds:

-Your current rear wheel: Is it running a thread-on freewheel, or a cassette? If It's a cassette hub, all you'll need is a single cog (in your preferred size) and some spacers. If it's a freewheel hub, you could re-dish it to accept a singlespeed freewheel (as others have mentioned), but i'd only do this if everything is in tip-top condition. Otherwise, it would be advisable to get a new wheel, probably a SS-specific one. (Your guy at the shop can run over some options with you...)

-Your crankset: does it have the kind of chainrings that can be removed, or is it some sort of ghastly all-one-unit kind of thing? If the bike is of decent quality, it will be the former. You'd need a set of bmx/SS chainring bolts, and I'd suggest getting a new SS-specific chainring (these help prevent dropped chains over ramped/pinned chainrings for derailer set-ups). If it's the latter, where the individual chainrings cannot be removed independently from one another, you might want to consider a new crank, or just running the chain on the middle ring and leaving the inner and outer rings on.

Like so many things in life, you could do this for $0 (shorten the chain, bypass derailers, run the chain on the middle ring and whichever cog on the back lines up most closely) to well over $1000 (all-new, high-end wheelset, crank, etc...) I suspect you'll fall somewhere in the low-to-middle end of this spectrum. Your LBS guy probably already thinks your crazy, but if he's at all a cool wrench, he'll be glad to do your SS conversion project for ya. =D

-rob
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Old 05-22-12, 06:26 PM   #16
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Are you sure about that? Now you have me curious. When I get home, I think I have one bike that has biopace rings. I am going to watch the rear derailleur and see if it stays put while I spin the pedals backwards. if the rear cage stays put, then I think you are onto something. if the rear cage moves around, then your info is most likely false. Interesting.
Quoth Sheldon-
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People are often astonished to learn that I ride Biopace chainrings on fixed-gear bikes. They imagine that there will be tremendous changes in chain tension as the chainring rotates. In practice, this is not the case. A 42 tooth chainring will generally engage 21 teeth against 21 chain rollers, regardless of its shape.

There is a slight variation in tension resulting from the varying angle between the two straight runs of chain as the axis of the chainring rotates, but this has not generally been of a sufficient magnitude to cause any problem in practice for me.
Also, an old spoke in an old rear deraileur makes for a great way to hold the RD in place to use as a chain tensioner if you don't want to spring for one of these-

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Old 05-22-12, 07:06 PM   #17
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More important to me than what Sheldon Brown says about HIS experience (notice he says "for me") is my experience. Maybe I'm too particular and theoretically it works with causing a problem, but I couldn't get the tension just right FOR ME until I changed nothing but the chain ring. Then, presto, it was beautiful. For the record, I utilize Sheldon's site often.

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Quoth Sheldon-


Also, an old spoke in an old rear deraileur makes for a great way to hold the RD in place to use as a chain tensioner if you don't want to spring for one of these-

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Old 05-23-12, 12:17 PM   #18
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You need to spend a little time going through this Singlespeed FAQ; it should answer all your questions http://www.mtbr.com/ssfaqcrx.aspx
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Old 05-24-12, 05:06 AM   #19
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The original question: no a bike mechanic won't think you're crazy. If they do, try another shop. This is pretty standard stuff that we do for our customers all the time. But, doing it yourself is more fun
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Old 05-24-12, 12:39 PM   #20
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The original question: no a bike mechanic won't think you're crazy. If they do, try another shop. This is pretty standard stuff that we do for our customers all the time. But, doing it yourself is more fun
I do really want to do it myself, I've been really overwhelmed with a lot of the technical talk on the how-to's I have been finding, I am bit afraid that I will mess something up.

Because well, a few weeks ago I was messing around with my daughters old bike turning it into a balance bike and I was having a blast but I was done so I decided to open up the back wheel and attempt to disable the brakes so the wheel could go both ways. I got the brake pads out no problem but getting it back together and on the bike and spinning right was more of a challange then I expected. I think I got it right and did not mess anything up to bad but who knows. The wheel does go both way though.

It seems to me visually that removing the derailers (of what ever they are called, I can see them on my bike) and running the chain on the middle gear in front to the straightest in line gear in the back will work mechanically. I can shorten the chain, and if I need to I can adjust the position of the back wheel within the drop out.
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Old 05-24-12, 12:42 PM   #21
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You need to spend a little time going through this Singlespeed FAQ; it should answer all your questions http://www.mtbr.com/ssfaqcrx.aspx
That's the how-to that left me overwhelmed, all of the technical language is confusing for a newb like me that did not even know what a drop out was a few days ago. However I have re-read it several times now and over time it is starting to make more sense.
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Old 05-24-12, 12:43 PM   #22
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I do really want to do it myself, I've been really overwhelmed with a lot of the technical talk on the how-to's I have been finding, I am bit afraid that I will mess something up.

Because well, a few weeks ago I was messing around with my daughters old bike turning it into a balance bike and I was having a blast but I was done so I decided to open up the back wheel and attempt to disable the brakes so the wheel could go both ways. I got the brake pads out no problem but getting it back together and on the bike and spinning right was more of a challange then I expected. I think I got it right and did not mess anything up to bad but who knows. The wheel does go both way though.

It seems to me visually that removing the derailers (of what ever they are called, I can see them on my bike) and running the chain on the middle gear in front to the straightest in line gear in the back will work mechanically. I can shorten the chain, and if I need to I can adjust the position of the back wheel within the drop out.
Yes, from your description, I believe it will. Just do it.
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