tgzzzz

Per earlier posts about the high gear ratios on the 8H, I got a used set of rings off the net ($10 with shipping), a Shimano 40T to replace my standard 46T plus a matched 52 to grind and make a new chainguard out of. While it was easy to swap the ring, as advised, I soon realized that my chain is now too long.

OK, I should have known there are no 5 min jobs and knowing how to adjust the chain length won't kill me and maybe a master link in the chain will help me down/on the road to boot. And, I now know I also need 5 longer ring bolts for the new guard. For test purposes, however, I was able to pull the back wheel to the bitter end of the slots and tighten it temporarily. After removing one of the rear brake shoes, that is.

What a difference the 40T gear makes! I now have much lower gearing at the bottom end and the top couple of gears, 7 & 8, are still just fine, for me at least. With the 46T, those two highest gears were not going to get used much and the bottom end sucked. The earth ain't flat. And I didn't have to mess with the rear cog at all. Another good thing was the gear shift adjustment didn't change!

And not to be overlooked: the bike now weighs approximately 6 pounds less! That's about the difference between the stock cheapass steel chainring and the alloy Shimano.

Questions:
1. The new (used) 40T ring is a mm or so narrower than the stock 46T. While there is some side-to-side clearance (slop) on the new setup, there was likewise some on the factory ring too. Should I care? If so, can someone recommend a specific new ring to buy?

2. The LBS installed a 122mm Shimano sealed BB earlier, and when I looked it over, it seemed the front and rear gears didn't line up as well as before. Is the 122 the correct width? Given that derailer chains are routinely not lined up exactly, is the misalignment something to worry about?

Thanks in advance.

spambait11

^^ A chainline that is out of line by 2-3mm is acceptable though not as aesthetically pleasing.

Kabir

I remember Yan said in this thread that the BB is 68x115mm. And, a steel chainring can weight 6 pounds more?! I find ourself having a hard time believing it. Maybe I should swap the chainring on my NS, too?

tgzzzz

I'd forgotten the 68 x 115 spec. That's what's wrong. Mine is 68 x 122, so the chainline (I've just finished Sheldon Brown's material) is 7 mm/2 too wide, ergo my chain is 3.5 mm out of line with the rear sprocket. It looks it too. I bet my chances of getting the LBS to put in the correct BB for free are not too good. They're going to say it's OK. Now I am doubly sorry I wussed out and didn't buy the tools to do it myself.

It's possible that the stock steel chainring, while remarkably heavy, didn't weigh all of 6 pounds. I was jes' sayin'.

invisiblehand

But it isn't OK with you. Ask them to do the job right and put on an appropriate bottom bracket.

tgzzzz

Thanks for the inspiration. She was cool about it. Said she'd not only RnR the BB but upgrade it as well. She wanted me to be happy. Why don't all women want that same thing?

cmcanulty

I really want the downtube 2006 20" NS but has anyone yet tried to break it down to legal airline size? How much would it entail and is it even possible? I have a 29" soft Samsonite that I've lined with heavy cardboard and it easily fits my 16" one speed folder. But I need gears and prefer no suspension and getting the rack and fenders. I know this was asked on this thread but it was a long while ago and no one answered, thanks

cmcanulty

I was all set to buy this then had second thoughts after spending a few days reading all the posts. Here are my 2 issues 1) Yans web page says it weighs 24 lbs minus rack, kickstand, and fenders. So I figure 3-4 lbs at most for those things giving a max of 28 lbs. Then I see a thread where someone weighs their NS at 33-34 lbs! That's a huge difference, what is the legit weight? The other issue is many posts talk about too high gearing, which is a big issue for me as I carry a small dog, groceries, books, etc. The posts were talking about the biggest rear cog at 25-28 on vearious DTs yet the 2007 NS says a 32 rear cog which would be fine, which is correct on this? I really want one but if the weight is really 32 lbs I'll get a Dahon Mariner at 25.7 lbs complete. And f the rear cog is actually 32 then DT is fine for gearing. Thanks, and sorry to be so questioning but I need to get the right folder.

-=(8)=-

I have an NS but not a scale so when I say there is no way mine
is even 30lbs its based on wieghts of other bicyles I own. 28 sounds about right,
out-of-the-box.
Gearing is subjective. I live in FL and have exactly one area that might qualify as
a legitimate 'hill' (intercoastal bridge) but even in Vermont where I moved from,
the gearing would be too low, as in too easy. I only use 5th through 9th. 9th is
80 gear inch's on mine so thats plenty of top speed. I cannot imagine a situation
where 1st or 2nd gear would ever be needed on one of these. In VT I can only think
of a few hills I would even drop to third in, but gearing all depends on wht works for you.
Hope thats of some help. The only other opinion I can offer is that mine starts to ride
sort of ruff when the road is broken up a little more than Im used to on a large wheel
bike. In another post someone suggested Big Apples which hopefully will help with that
before I go radical with a heavy Thudbuster type post.
I also cant help with the breakdown size. I have mine set up with so many lights and
mirriors, waterbottle, pumps and such it would be a half hour just to get the commuter
type junk off of it, sorry. Hope the other stuff helps a little.

cmcanulty

Well I think gear inches are pretty standard. My question is does the DT 20"NS really come with a 32 inch largest cog or is it 23 or 25? Big difference in gear. Several posts seemed to indicate it is 23 or 25, the web site says 32. Thanks

iPAQsRock

This is a great thread, took me several days to read all the way through!

I'm looking to purchase a Downtube, have a couple questions about modifications.

Is it possible to replace the v brakes with disk brakes front and rear?

I like the 8FH, but was hoping for Orange. Did this bike come in more colors at one time, but all that is left know is White?

invisiblehand

I believe Yan's SA-8 hubs have 23t. The bikes with a derailer have a 11-32 cassette (or something similar to that). I believe that there is no 32t cog for an SA-8.

invisiblehand

Excellent!!!

invisiblehand

I ran into a few Downtube FS bikes in Arlington and DC. They let me putz with them and I would be shocked if they were over 30 pounds.

My take on the various reports is the the 20" internal hub bikes are geared too high--really has to do with the SA-8 design--and that the derailer bikes are more on target. However, it really is not that difficult to change the gearing by swapping the chainring.

Note that you should only take other people's reports so far. If you already have a bike, calculate its gearing and compare it to the folder. For instance, I can get away with a bike geared lower than those I ride with since I spin with a relatively high cadence.

spambait11

Another datum point: as a result of folding/unfolding my 2007 FS IX derailleur version, I'm now getting the phantom shift problem which never happened when I wasn't folding the bike. Like others have said, folding must do a number on the cable tension in some way. I plan to look into this more when I have more time. I also agree that the phantom shifting problem is annoying.

cmcanulty

Would this cassette work on the DT Mini? A lot lower gearing and cheaper also
Shimano Deore LX M580 LX 9-speed cassette 11 - 32T
Code: CSM5809132
Price: £ 29.99
Stock: In stock

• High quality 9-speed cassette
• Hyperglide sprockets have a computer designed tooth configuration with contoured shift gates, resulting in a crisp smooth shift even under load
• Close ratio gearing allows a more efficient use ofenergy through finer cadence control
• Sprockets are cut away and drilled to reduce weight without reducing rigidity
• Pearl-bright finish offers hard wearing resistance to corrosion
• Pearl-bright steel cassette lockring
• For Super Narrow 9-speed HGchains
• Weight: 339 grams for 11 - 32T

SesameCrunch

Huh??? The DT Mini comes either with the SA8 internal hub, or a 9 speed Capreo. This cassette wouldn't apply in either case. Did you mean to ask this about the NS? If so, yes.

invisiblehand

+1

The Capreo hub is only compatible with the Capreo cassette.

Really, just change the chainring ...

cmcanulty

I must be stupid but I need to know what tires & tubes will fit my new DT 2007NS 20" bike. I understand it comes with 20x1.5 front and 20x1.75 rear. But then why are people talking about sizes like 406 and 460? I just want a fast fairly narrow high pressure road tire that is durable. But how do I know which widths will fit this bike, thanks, from a dummie

JosephLMonti

The wheels on your DT are 20 inch, but be aware that "20 inch" actually refers to two different wheel sizes, 406mm and 451mm...you have 406mm. Please note that these two sizes are NOT interchangeable. In terms of width, the DT will take 2.0 like the Big Apples and probably even wider. For something high pressure and narrow, maybe try the Scwalbe Stelvios.

JosephLMonti

I had previously mentioned in some other threads that I would be switching out my DT's shock for a rigid fork. I finally got this done and have some pics . The steering tube on the rigid fork was longer than on the shock so the folding section on the lower handlepost now sits about 1 inch above the headset, where before it was flush with the headset (see pic). To compensate, I just cut down the top portion of the handlepost so that stem sits on top of the quick release (see other pic)...this gives me the original handlebar height before the switch.

My initial impressions - The bike is noticeably lighter...I think by about 2 pounds. Also, the rigid fork has less rake and is slightly shorter than the shock. This made the steering angle slightly steeper and the wheelbase a tiny bit shorter...the effect is a more responsive ride. The rigid fork also made the ride a bit harsher...no problem, I just switched out my Hookworms for a set of Big Apples (thanks, Thor!).

Overall, I am very pleased with this mod and will probably make my next DT the NS, since that frame is lighter as well.

spambait11

Found that if I adjust the derailleur adjuster so that the cable becomes fairly slack, the phantom shift problem goes away. Am good to go once again.

cmcanulty

Everyone says downtube has great support but I ordered a bike a week ago and no one will return my call as to a shipping or receiving date.

invisiblehand

In my experience, I had much more success e-mailing Yan directly than any other method.

cmcanulty

Got my DT NS 2007 today! Generally looks good though I am disappointed it came with plastic pedals not the alloy stated on the web site. What is the handle type thing under the BB? Also I can't get it to fold as I can't seem to release the handlebars, they have a QR plus a button to push. I have tried mightily but no luck getting it to release. Help as I need it for a trip next week!