Help with low-cost SS conversion..
 

Background info: (optional ;))

I recently built up a new mountain bike, cannibalizing some parts from my old bike, a 1993 Tange Prestige Stumpjumper. I love the old bike, and can't bear to throw it out, and at the same time, i've been wishing i had a bike for tooling around the city and suburbs on. I was thinking about buying a road bike, but last night i checked the numbers and ****.. i'm nearly broke :p

So.. I started thinking about fixing up the Stumpjumper, and since i'm broke, and most of the drivetrain went onto the new bike, i figured i should go singlespeed. To be honest, i never quite understood the appeal of singlespeed, but on the other hand, i've never ridden one since i was 8 years old, so this seems like the perfect opportunity since it would also save some money on new shifters/derailers/cables/cassette etc.


The question:
Anyway, here's where i think i need the advice.

What i have is a 26" wheeled mountain bike, with a Sugino Impel crankset (42-32-22), and a Deore XT rear cassette hub (cassette itself is gone to the other bike).

I understand that what i need here is a Shimano BMX cog plus a bunch of spacers, plus a chain tensioner (the bike has vertical dropouts). Can i use any BMX cog, or do i need to get a special one to fit on a cassette hub?
Is any chain tensioner ok? This one was the cheapest i could find, and on top, the shop is pretty close to me: http://nycbikes.com/item.php?item_id=411

As for the cranks, which chainring should i use? Can i, say, use the middle chainring and simply take off the granny and big ring?

What is a good gear ratio? I plan to use the bike for city use, with slicks. I live in NYC, so there are a few hills, but nothing huge. If i use the 32T middle chainring, what is a good rear sprocket size?

Finally, the rim on the rear wheel is in bad shape, it has a hop that nobody seems to be able to repair. If i'm going to use the bike as a SS, is it worth rebuilding the wheel using the XT cassette hub, or should i get a dedicated SS rear wheel? (ie. which would be more expensive?)


And in general, any suggestions for getting this stuff as cheaply as possible? I'm hoping to keep the budget under $100, if that's possible..

Sorry about all the questions, it's my first time dealing with anything related to SS.


Thanks!

My suggestion would be to get at 16t cog to fit on the cassette, and line it up with the outer ring on the front. 42/16 is a very common, relatively easy gear for riding on the road. Any chain tensioner would work, but try it without one first. You might be surprised. Lastly on that wheel... its your choice whether to use it or not. I'd say find a used wheel. If you're feeling like spending some money on it, buy the IRO wheel that has a fixed/fixed hub. It'll take bmx freewheels also.

You've got some options here. Chris King, Surly, endless bikes and Shimano all make cogs that will fit your hub. Some other BMX cogs might fit too, I'd suggest taking it to a shop and trying it out.
NYCbikes has received VERY mixed reviews on this board. If you still have your rear derailleur, you can use that, also. But, some prefer to reduce the number of little pulleys...
Unless the rings are riveted together (as is sometimes the case with cheap cranksets), sure. Though I'd suggest keeping the big ring if you're going to use it in the city. Folks usually run a 32 ring for off-road riding.
What's a good pizza topping? Most people run anywhere from 60 inches to 80, so that's about a 2.3 to a 3.1 for 26" MTB wheels. You'll have to make a leap of faith, maybe try out someone else's bike (at NYC bikes?) to get an idea.
Replacing the rim, spokes, nipples, etc. will definitely cost less than buying a whole new wheel, especially if you are already using a cassette system.
The CL and ebay are your friends. Also, make friends at bike shops, they might have used stuff for you.

Everyone's got to start somewhere additional information on SS can be found here: MTBR SS FAQ

Thanks. I called the bike shop down the road from me.. the guy said they had some chain tensioners for $20, and a 'conversion kit' consisting of two wide spacers and a 16 tooth cog for $25.. the problem with the conversion kit, he said, was that it didn't allow chainline adjustment, but "that's what the chain tensioner is for"..

The last statement sounds strange to me, but i didn't want to get into an argument over the phone!

Anyway, i think i might mosey on down there and see what they have.

How much should i expect to pay for a rebuilt rear wheel with new spokes, nipples, and rim on an old hub? I don't need super strong stuff, since i'll be riding on road mostly..

I'm guessing that conversion kit is junk. If you can't adjust chainline, it's useless. Just get a cog (try and do better than the Shimano DX cogs, they have a very narrow base that tends to dig into your hub body) and use PVC pipe from the hardware store to space it. Cheap and ugly, but effective.

Rebuilding of a wheel shouldn't be too much... Do yourself a favor and take it apart yourself. Then just walk in and say you want a new rim put on there. Cheapo rim ~$20, new spokes & nips $10, and whatever they charge for labor, prob around $20 (just guessing here).

--yer gonna need to get a set of single-ring binder bolts--your current chainring bolts are too big

--IMO, your best bet is to use the cassette hub. the spacers and cog will give you good chainline adjustability. the only other good option with vertical drops would the white industries eccentric hub--expensive

--so far as I see, you need a rim, spokes, a set of chainring bolts, a cog, and spacers. keep the rear der and use it with the limits locked shouldn't bee too hard to keep it under 100.

Is your ring compatible with a 3/32 or 1/8 chain? Based on that go and get a Novatech, Shimano DX, Surly or Endless cog. The King and Boone are more expensive.

Left to right, Boone, King, Novatech. The wider the cog the least prone to damaging the freehub specially if the freehub is made from aluminum.

http://i14.photobucket.com/albums/a3...f/PC080006.jpg

For spacers use pieces of 1 1/4 Sch40 PVC pipe, cut to size.

http://i14.photobucket.com/albums/a3...f/P5020002.jpg

http://i14.photobucket.com/albums/a3...f/P2050002.jpg

For tensionining your chain, try if first with only the chain. If it's too long get a half link and git it a try. Tensioners are prone to problems but are required sometimes.

Half link

http://i14.photobucket.com/albums/a3...f/P1250005.jpg

You should be able to convert your bike for around $50.

Hope this helps.

Thanks everyone.

I just took apart the old wheel. It was a custom job i ordered from Supergo a decade ago, and man, what a crappy build. When i was taking it apart, i found that the nipples were all nearly stuck (no spoke prep, i guess) and the spokes weren't even all the same gauge! (they were supposed to be DT Revolution, which were $$$ back then) The wheel has been a real headache.. it was never ridden hard, but was _always_ out of true, and a couple shops just told me that it was a crap build and it couldn't be fixed. Good riddance, i guess.

Anyway, i think i'm going to try to build the wheel myself, since a Minoura truing stand from Nashbar is cheaper than a wheelbuild here (in NYC, everything is jacked up. Places charge $1 per spoke and $1 per nipple for straight 14 gauge spokes, and at least $40 for a build), and i've always wanted to try it.

As for the PVC, that sounds cool, but how do you cut it so straight?

I think i will go with a chain tensioner since i'm not sure what gear ratio is right, so having a tensioner should make swapping stuff around a lot easier.

Thanks.. i'll keep you all updated :p

One more thing.. after testing with a magnet, it seems that the splined rachety cylinder part of the hub is steel (is that called the cassette body?). I guess that means i can just go for the cheapest sprocket, and not worry about width, right?

couple of hosepipe clamps, one on each side of the cut, help to guide when sawing tube. real useful for steerers

Great Pics dirtdevil. I'd say he has a 3/32" chain, considering it came from a geared bike in the early 90's, and not a BMX or track bike.

Also, don't rule out a Surly cog! They just started selling their cassette cogs, and they look beefy as hell. For a comparison I nabbed this from Harris cycler. From left to right: Shimano BMX , Chris King, Shimano Hyperglide (AVOID), and Surly. http://www.sheldonbrown.com/harris/images/bmx-cogs.jpg

Wheelbuilding isn't reall thay hard--you can totally figure it out with a little patience. A good truing stand is MUCH better than a not-so-good one, though.

If you come down to the Time's Up co-op with your wheel, I might be able to help you lace or tension it--I volunteer there sometimes.

^ Cool, thanks. I don't even know what the Time's Up co-op is though...

I got slightly carried away while ordering at Nashbar and splurged on a silver SRAM 1/8 BMX type chain. I'm guessing it will go perfectly with a Shimano DX cog on the rear, and should be ok with the 3/32 chainwheel up front..

Just wondering.. how much should i expect to pay for a used lockring to hold the PVC and cog onto the cassette body?

NYC bike shops have a tendency to price things kinda high, so I just wanted to have a ballpark figure in mind when i ask the guy to check in the parts bin.


Also, do i have to torque the lockring very tight? When installing a regular cassette, you torque it a lot, but with the PVC spacers, I imagine you have to go easy?

use the lockridng from your old cassette! i ususally put the last little cog on as well just to make sure the spacers don't push straight against the lockring.

for spacers, if you can get a couple old cassettes (you can bust out the rivets so the whole thing comes apart) , the spacers from those work perfectly and allow you plenty of adjustment for you chainline. you will need more than one cassettes worth though....

DX cog is great and i don't see the sense in paying more for anything else unless you need a size shimano don't make.

To cut the PVC I use this mitter box, got it at Home Depot.

http://imagex.homedepot.com/f/248/13...s/165693_3.jpg

Just installed a Surly on my neighboors bike, looks nice and sturdy. Another cheap alternative is the Endless Kick A$$ Cog.

http://www.endlessbikes.com/products...n_cogmulti.jpg

http://www.endlessbikes.com/products...ents/cogs.html

YESSSSS, get the cheap DX (1/8" chain) or a Novatech (3/32" chain).

Just use the one from the casstte you just removed.

I go by feel, just the same as a regular cassette.

From another thread, someone suggested just buying an IRO 26" rear wheel with a fixed/free flip flop hub. You don't have to screw around with the spacers etc and for $90 it sounds like you'd save a bunch of time and effort and have a brand new wheel all built up.

Unless you really want to experience of building up the wheel and playing with the spacers which I can totally understand. Money/time wise though it seems like a toss up, depending on how you value your time.

re. using the lockring from the old cassette

As mentioned earlier, the old cassette is on another bike, which is why i'm asking about buying a new one! :)

So the question still stands: how much should i expect to pay for one?


Thanks!

Sorry, don't know a price for it. Do you know the guy that wrenches at the shop? Sometimes they have those laying around and if you ask may give it for nothing.

New lockrings come with every new cassette, so if they're nice, they'll give a used one to you, or save one for you from an old cassette they change out.

If they're not so nice, I'd say a couple of bux (<$5) would be a fair price for a used one.

aebike has the Novatech and Shimano (XT/LX/Ultegra) at $7.99, King only works with King hubs and so does Campagnolo.

http://aebike.com/site/images/librar...50m/FW8378.jpg

You'll also need a lockring tool

http://images.mec.ca/media/Images/Pr...9830534922.jpg

Thanks :) I live in NYC, which means that people who work at bike stores aren't usually nice :p

I actually went to two stores today. Neither of them had a BMX sprocket or a lockring, nor _any_ spacers. I asked if they didn't have a parts bin or something, and they were like "We don't keep old parts.".

:(