downtube

I did not go with a 9sp at first due to cost. I'd love to swap over now if I had a choice. However, just last week I was told 9sp components would not be available.

I hope they will be available in January, if so I will spec them on the Downtube IX.

Thanks,
Yan

af895

If I'm interpreting what you're saying correctly, your concern has to do with greater distance between smallest and largest cog in a 9-speed cassette versus and 8-speed - with a short wheelbase the chain off-axis angle is greater.

I *think* it's the same cassette width so as long as an 8-speed work vis-a-vis chain angle, a 9-would be identical - it just packs more cogs in the same space.

Am I off base with any of that?

jasong

Yes, the cassette is identically wide for 8sp and 9 speed. I've just read that others had had problems in well estimating number of usable gears in small wheelbase (is there a better word for rear_hub-BB distance?) applications, which would explain well why so many folders seem to be 5-6-7 speed and not 9 speed (ie. Dahon Boardwalk 7 speed).

There is indeed a bit greater bend in the extremes of the individual cogs, because each cog is a bit narrower. So while the left side of the chain is laterally as far left on the big cog for 8sp/9sp, the right side of it is a fraction of a millimeter further left. Imagining decreasing the wheelbase to an arbitrarily small value where it's obvious that the chain couldn't bend well means that somewhere between this value and a normal bike wheelbase is where a difficulty will arise.

But, as Yan has just posted, apparently there isn't an issue since that wasn't the reason for not including 9 speed. Perhaps on a bit smaller folder. FYI - I had read this in regard to mods people had used for trying to do a derailleur solution on 16" bikes (where you rarely do seem to see a multispeed derailleur, but instead a flat chainline and internal speed hub).

jasong

Well, thanks to your design using more standardized parts, one can "upgrade" their drivetrain to 9speed for minimal cost (no more than $40-50, assuming that the rear derailleur might not complain too much). Personally, I don't mind being "limited" with the 8 speeds. The overall ratio is what's most important to me, and that's really quite ample. One can even go further with the 11-34 cassettes (originally spec'ed as 11-28) to get an extra 55% gear range (309% vs. 254%), also assuming that the shipped derailleur's cage is adequate (capacity won't be an issue for lack of front rings, but perhaps max difference since the spec'd cassette appears more road like). I've run a road bike with a long cage mtn rear derailleur in this setup for a while and like the low gearing at times (only 2 rings in front). Wonder if a really long derailleur cage on the 20" wheels would actually hit the ground..

This flexibility precisely what I've been looking for in a folder design. And I'll be looking forward to playing with my new one - I just bought a VIII online.

jpscsunil

How on Earth did you get the bike to fit in the bag! I picked up my DT VIII today, and neither I, nor the woman who showed me how to fold/unfold the bike could get it entirely in the bag. We were able to zip on both sides, but the squarish metal bar on the bottom of the bike (sort of like a stand, but not the kick stand) kept us from completely zipping the bag. Any suggestions would be greatly appreciated!

af895

jpscunil: try flipping the bike upside-down or "slide" the bag onto the bike so the zipper is on the bottom before closing it.

Just suggesting that because of this pic: https://www.downtube.com/images/Bikes_7-14/BikeinBag.jpg

Which shows the stand you're referring to on the zipper side of the bag.

jpscsunil

Thanks for the suggestion. I tried one more time and finally got it right. The Downtube person left the seat on, but took the handle bars off. She said she is able to leave the seat on with her VIII FS. As it turns out, the seat comes off and the handle bars stay on! Too bad, because it's tough getting that seat off. I may do what someone on one of the posts suggested: cut an inch off the post so the seat does not have to be removed. I've had this bike less than 12 hours, and I love it already! \

BTW, it is easiest to leave the bike right side up, and put the cover over the bike, then turn the bike upside down - the zipper is then on top.

BruceMetras

Hi Yan!

Hi Downtubers!!

Still really enjoying my VIIIFS.. here's a couple of pics showing my update over the weekend. First time for me for anything like this... I laced up the 8spd Shimano Nexus 'red band' to an Alex16 rim. Very cool to ride... Slick and quiet.. easy to do with the horizontal dropouts. The Nexus has a 307% overall gear ratio...about the same as a 9spd mega-range 11-34...

Bruce

ps for Yan... I could use a couple more of those seatpost shims....thanks!

Mr_Super_Socks

dangit! you beat me to the punch! as you know, I had the same idea for my downtube viii, but I am afraid the vertical dropouts make it a far less appealing idea. may still try it with a singleator or some such jury-rigging, but yours looks great!

v1nce

Nice back wheel! Good job on the lacing. How many spokes and how long did the lacing take start to finish?

Rincewind8

Bruce,
I was thinking of converting my VIIIFS into a fixed gear, but since the hinge of the rear suspension arm is not at the bottom bracket I fear that every time I hit a bump it is going to mess up the chain tension or throw the chain. How is the chain tension holding up for you, since you don't run any chain tensioner?

BruceMetras

Yo Vince, Thanks!... I know this kind of thing is 'old hat' for many on the list, but for me it was exciting. The Nexus hub is a 36 hole unit. So I picked the Alex DA-16 Aero rim, 1.8mm spokes laced 2x and at the moment, running a Kenda Kwest 20x1.5 100psi. I'm sure it took me way too long, and my hat is off to all those who charge $30 or $40 bucks to build wheels, but I started on Sunday afternoon and probably spent a solid 4hrs on it by the time it was trued. I let it sit overnight and checked tension again and then mounted it to the bike on Monday night. The only snag was the new supplied shift cable was surprisingly about 4" shorter than my stock one, so I had to run down to Performance and spend $2.50 on a longer cable. I wasn't pressed for time, so I took a lot of it...haha

Bruce

BruceMetras

Hi Rincewind8,

When I set up the chain tension initially, I loaded the rear suspension first, set what I considered nomal tension and that was it. It does tend to tighten when suspension is compressed, so if you set it tight unloaded, it will be too tight when ridden. Just came back from my 10mi lunch run and it worked perfect. The shifting is very smooth and the hub surprisingly quiet in any gear. I jumped a few curbs for grins and didn't loose the chain. I can't see how it would, but my impending trail riding should be a good test. I don't know how critical chain tension is on a fixed gear bike, but worse case scenario, a tensioner could be added.

Bruce

jasong

Where did you buy the Nexus-8? Price? Any feelings of inefficiencies with it?

That's cool!

14R 

That is cool. Now, any imput on those working with a 7s cassete and derailleur at the same time?

Your bike looks awesome by the way!

jasong

What do you mean- Input on building a wheel around a normal freehub rear hub?

Mr_Super_Socks

you need a sram 3x9 for that. I've got one on a dahon and (and a sachs 3x7 on my bike friday.) gives an impressive range of gears. sheldon brown has converted standard geared hub to work with a cassette, but it requires a bit of work.
https://www.sram.com/en/sram/comfort/...ubcassette.php

14R 

No, sorry for my lack of details:

My curiosity is around a geared hub (speed hub) used simultaneously with a regular 6,7,8 or 9 speed cassete.

Without a front derailleur, you can still reach 126 gears (14rohloff x9speed cassete).

My bike cannot fit a front derailleur, so I may consider in the future a speed hub if that is do-able (if I can get it and keep the current 7 speeds that I have)

Thank you,

Rafael

Rincewind8

Why do you need 126 gears? Or anything close to that? Are you trying to set a speed record and pull a 500lb trailer with the same bike?

BruceMetras

Rafael, you want a SRAM DualDrive This hub came standard on my Dahon SpeedPro and also the Speed TR and is used on many Bike Friday configs as well as a host of others ... it is an awesome solution for small wheeled bikes that spend most all there time on pavement. Especially good for touring as it employs a mega gear range for climbing or pedaling those 35+mph downhills. I've had zero problems with mine.

Bruce

BruceMetras

It was $166.95 and I bought it retail online from BikeMan. Their service was excellent and has continued to be as I've purchased other things also.

I don't find the Nexus inefficient. Actually, the opposite. It shifts smooth, the chainline is always straight, it's pretty quiet, the ratios are nice and you can tailor the overall gear ratio with easily replaceable sprockets from 13t to 21t. In the last couple of days of riding, it is faster than before, but I attribute that in part to the 100psi Kenda Kwest on the rear. It does weigh a little more than the stock wheel/derailleur setup, but the extra mass is at least in the best place possible, in the center of the wheel.

Bruce

14R 

That is what I was considering actually.

I have a trip to south america (already scheduled for this december) that will be my final test for the current configuration of my bike. If I feel the need of more gears (either low or high) my only solution is a hub, and the SRAM dualdrive is one of my options.

Now, the 3 gears that it brings to the bike, are those low-equal-high compared to a non-geared hub or Super-low/low/still-low or high/higher/highest?

In other words, will it increase my range or just increase my number of gears in one direction (low or high).

Thank you,

Rafael

BruceMetras

The Dual Drive 3spd hub is: Low (underdrive) Middle (direct drive) and High (overdrive)..you can play with some online gear calculators to find a 'gear inches' range that would suit you. The overall range of even the 7x3 21 speed is over 500%.

One more option, although not inexpensive is a SpeedDrive. I have one of these going into a Jet XP when I get the time.. They are terrific, Swiss made, and another solution for extending the gear range of a single chainring bike.

Bruce

14R 

Not really! I just live in Florida (still looking for a place on earth as flat as Florida) and mainly use the bike inside an University campus and as a recreational vehicle (50 miles a week at most). for these purposes, the bike is actually almost perfect ( a little low geared if I get picky).

However, I travel at least once a year to Brazil, where climbing mountains is a common practice. Since the idea is to have my bike as my only bike, I am just trying to expand my gear option.

I don't have a front derailleur, so I would never reach 100+ gears. All I need is some way to compensate the lack of 2 chainrings. Seems like a geared hub is a good option...I am just refining my research about it.

Besides the options mentioned here, is there anything else that can be done? (budget aprox US200.00)

Rafael

v1nce

Well Rafael i was thinking about just using a Sturmey Archer 3 or 5 speed (cheap as NOS) and a triple front chain ring... Is this even possible, and especially is it possible on a folder? The range wouldn't be massive and the gears wouldn't be loads but enough for quite a lot of applications. Plus it would be cheap & durable i guess. But maybe it is totally unworkable? I don't know.