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Downtube folding bike

Old 01-12-07, 01:59 PM
  #901  
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ooops, the link is www.cruzbike.com. I have corrected it in the original post.

Here's a picture from their website:

And here's a mock-up:

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Old 01-15-07, 06:23 AM
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How do I mend a Zoom suspension fork in the UK?

Hi there, I need to find some replacement parts to fix my Downtube suspension fork. All the travel in the fork has gone so I've no bounce to the ounce!

The bike shop said that they were familiar with the zoom brand but couldn't source parts from them as zoom only deal with manufacturers and not repair shops. does anyone have any info that can help me?

Searching through this excellent forum and google I can see that its possible to source various forks and parts in the US but I can't find much useful info for UK owners.

Does anyone know of a fork, suspension or not, that I can use as a replacement for the zoom, sourced in the UK? preferably with V brake mounts and similar geometry (tall order?)

Does anyone have any info as to how I can replace springs/elastimers/various bits in the zoom fork in the UK?

Hope someone can help - if only i lived in America i'd be laughing!

Barney
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Old 01-15-07, 07:20 AM
  #903  
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I'm not sure about the UK, but the suspension fork can be had on https://www.nycbikes.com/catalog.php?..._cat=WAREHOUSE For 9 dollars american. I'm sure they'd be willing to ship it over to the UK, it'll probably cost more for shipping than the suspension fork itself, but still, it'd be brand new.
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Old 01-15-07, 01:12 PM
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Originally Posted by SesameCrunch
ooops, the link is www.cruzbike.com. I have corrected it in the original post.

And here's a mock-up:
WHOA! That looks do-able. When I first read your post I couldn't picture it, but that helped a lot. Cruzbikes are pretty cool, the only negative I've heard is the adjustment to peddling as you turn...

Keep us posted!

Dan
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Old 01-15-07, 01:39 PM
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I will keep you posted. I haven't fully decided yet whether it's the folding bike or the mountain bike that gets converted. Each has its own benefits. I should do both....
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Old 01-15-07, 01:47 PM
  #906  
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For a Cruzbike mod, that seat looks way too close to the hinge: might impede x-seam adjustment. Also, for the front wheel drive, won't you have to widen the forks? That Dahon-looking bike in the photo would not be a good candidate for such a mod, esp. if it comes with the narrow Dahon forks. It also looks like the hinge on the handlebar post would prevent a secure mount for the Cruzbike stays. Nice idea though.
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Old 01-15-07, 03:12 PM
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New IXNS

Well I said I’d post a pic and give a quick report when I was able to take the bike out for a shakedown run. First, the bike came out of the box without a flaw. A few adjustments and it was ready to go. I was impressed with the handling and the ride-ability – definitely a nice bike for the price. I’m planning on swapping out the seat. Is there any real weight savings by removing the rack and kickstand – they appear to be light – but looks can be deceiving…

Dan

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Old 01-15-07, 10:50 PM
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Default seat is very heavy. Rack is fairly light.
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Old 01-15-07, 11:16 PM
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Originally Posted by spambait11
For a Cruzbike mod, that seat looks way too close to the hinge: might impede x-seam adjustment. Also, for the front wheel drive, won't you have to widen the forks? That Dahon-looking bike in the photo would not be a good candidate for such a mod, esp. if it comes with the narrow Dahon forks. It also looks like the hinge on the handlebar post would prevent a secure mount for the Cruzbike stays. Nice idea though.
Responses to your observations:
- First, this was just a rendering done by the designer of Cruzbike, not a "real" plan
- I would move the seat forward a bit as you say,
- I would be converting a DT IX Front Suspension, not a Dahon
- The Cruzbike kit comes with a bracket that attaches to the front forks which would widen it to 130mm,
- I don't quite know how the handlebar hinge would work yet. Have to see the kit in person.

I still don't know which bike I want to convert, but it's been fun thinking about the possibilities.

Spambait, do you have a Cruzbike or done a conversion?
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Old 01-15-07, 11:32 PM
  #910  
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Why do these Downtubes have adjustable stems?? Fore-aft adjustment is very small unless the stem is drastically set to 90* almost. Height is taken care of by the telescoping post, so it seems redundant...
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Old 01-15-07, 11:56 PM
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Originally Posted by SesameCrunch
Spambait, do you have a Cruzbike or done a conversion?
No I haven't done one.

I looked into it a couple years ago, but didn't have the kind of bike they wanted you to use (i.e. a mountain bike with a sloping top tube). I see they're selling kits with their own bikes now, but like you, I think modding my own would be more fun.

Recumbent kits for Bromptons and Birdys have been designed and sold in the past, but they were short lived.
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Old 01-16-07, 07:09 AM
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Originally Posted by BigMacFU
Default seat is very heavy. Rack is fairly light.
Thanks. Yeah, that seat is a boat anchor!
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Old 01-16-07, 08:17 AM
  #913  
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fork

Hi,
Well, as someone else pointed out you can get replacements really cheap. But if you want to fix yours, here's what I did. I took it apart, removed the old grease, and re-greased it. The old grease had turned into a consistency like putty, which was preventing the fork from acting like a fork. Initially I had though I needed a spring replacement, but that turns out not to be the case. Once I filled it with new grease and put it back together, it was working almost like new again. I think I posted a description of how to take it apart in another message.

Morgan
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Old 01-17-07, 05:14 AM
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Originally Posted by mcgurme
Hi,
Well, as someone else pointed out you can get replacements really cheap. But if you want to fix yours, here's what I did. I took it apart, removed the old grease, and re-greased it. The old grease had turned into a consistency like putty, which was preventing the fork from acting like a fork. Initially I had though I needed a spring replacement, but that turns out not to be the case. Once I filled it with new grease and put it back together, it was working almost like new again. I think I posted a description of how to take it apart in another message.

Morgan
thanks mcgurme

i've never done any kind of work on a bike at all - do you think a beginner could do a job like this? i found your post and i know i need a long allen key, grease - patience? any thing else?
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Old 01-17-07, 02:58 PM
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Originally Posted by barneybarney
thanks mcgurme

i've never done any kind of work on a bike at all - do you think a beginner could do a job like this? i found your post and i know i need a long allen key, grease - patience? any thing else?
I'd love to know as much as possible about this job also. After reading your previous post, I have been meaning to do this as a preventive measure.
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Old 01-23-07, 05:48 PM
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Customized DT VIII

I finally finished the upgrades to my Downtube VIII Folding Bicycle

This is my second folding bike. The first was a Batavus Bat-a-fold with a square steel seatpost, built up with a Shimano 3-speed when I was working in a bike shop while goin to college in the 70s. This bike was damaged by the airlines (they dropped it and bent the front chainring). The gearing was limited and since I have way too many other bikes I haven't replaced it until now.

I bought a Downtube VIII with the 8-speed Sturmey-Archer hub in November 2006.

I plan on using the folding option in three ways:
1) I leave the bike in the back of my car so I can get exercise at lunchtime when I want

2) I want a bike for road trips which can safely be locked up inside the car without taking up too much room and having the option for riding on dirt trails as well as pavement.

3) I want a bike I can pack into a airline legal suitcase (Samsonite Oyster) for trips.


Modifications
I replaced crankset and bottom bracket with a used Shimano 105 39/53 tooth. The gear ratios with the stock chainring are too high. THe 39 tooth front ring makes for a much more useful bike.

I filed down teeth on 53 tooth chainring to make it into a chainguard. This chainring was used and I would never use the 53 tooth option on this bike. More useful to have it as a chainguard.

Replaced folding alloy pedals with Shimano SPD pedals. I prefer SPD pedals and cleats and the non-folding pedal is not an issue.

I like the little bar-ends and the stock bars, but replaced the stem with a longer one to get a better reach. That takes weight off the rear wheel and puts it onto the front wheel. I have the seatpost up about as far as it can go and that moves my rear-end close to being over the center of the rear wheel, which makes the bike climb poorly. The longer stem gives me a bike position similar to my other bikes and improved handling.

Replaced chain with SRAM chain and masterlink. Having a masterlink makes chain removal for suitcase packing easy.

Replaced brakes and brake levers with Avids. Nothing really wrong with the brakes that come on the bike, but I prefer the smaller Avid levers and the Avid brakes have more adjustment options.

Replaced stock saddle with WTB saddle. I prefer the smaller saddle and really like WTBs.

Removed rear fender after suitcase packing test. I plan on putting on a small coroplast plate under the rack to act like a fender. One less thing to worry about when packing the bike.

Added a Topeak pump, Planet Bike Aero wireless bike computer, new grips after the originals ripped, and added a bell I had lying around. Added a small seatpack for tools and misc stuff.

Added reflective tape to frame, stem, and cranks, and front and rear LED lights for night riding. The rear light is attached to the rear rack, replacing the reflector which came with the bike. The rack protects the light when the bike is folded.

The bike can easily be rolled around while folded which is a plus. I use Velcro One-wrap straps to hold the front fork to the rear rack when folded and to keep the handlebars with the bike when folded. When rolling the bike I leave the seat extended and use it as a handle. The bike balances nicely when being rolled.

I am very impressed with how nice the bike rides. Stock tires are OK and work well on pavement and dirt/gravel paths. The suspension fork smooths out the ride. Ride quality is good, and the bike handles well at speed. I am still having some minor issues with adjusting the hub, but like the range of gears. If you use a folding bike as a folding bike it will get banged around and internal-gear hubs are less prone to damage versus derailleur bikes.







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Old 01-24-07, 09:24 AM
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Pine Cone:

Very well done. I really like what you did with the crankset! Clever idea. Very good choices overall. Sounds like you're going to be very happy with your setup.
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Old 01-25-07, 12:00 PM
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I have a question about the fork and the possibilty of replacing it. Is the fork a threaded or threadless fork? Is it possible to replace the suspended fork, with an aftermarket non suspended version? If so who makes it, and how would it be done?
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Old 01-25-07, 01:56 PM
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DT has a version with a rigid fork.
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Old 01-25-07, 02:12 PM
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I know, but I was looking at the IH version or the FS version. I emailed Yan directly about this before, and he advised against changing the fork to a rigid one, but I still want to know if its possible. And if it is, what route to take to do so.
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Old 01-25-07, 03:29 PM
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Originally Posted by big boy phil
I know, but I was looking at the IH version or the FS version. I emailed Yan directly about this before, and he advised against changing the fork to a rigid one, but I still want to know if its possible. And if it is, what route to take to do so.
I was wondering the same thing. I would like to get the internal hub, but would try to shed as much weight as possible if I went that route, and the fork might be a part of that (anyone know how much difference it makes?) Wonder why Yan advises against it-did he say?

John

PS - my first post BTW-I am shopping for my first folder, and am down to Xootr Swift (need to save more $) vs. Downtube (can affordit now)

-John
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Old 01-25-07, 06:02 PM
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Originally Posted by John+++A+++
I was wondering the same thing. I would like to get the internal hub, but would try to shed as much weight as possible if I went that route, and the fork might be a part of that (anyone know how much difference it makes?) Wonder why Yan advises against it-did he say?

John

PS - my first post BTW-I am shopping for my first folder, and am down to Xootr Swift (need to save more $) vs. Downtube (can affordit now)

-John
I think I was was slightly misquoted.

I mentioned that the VIIIH's geometry was set up for a suspension fork. I never tested it with a rigid fork and will not have time to test it for a long time. Hence I discouraged the idea.

Thanks,
Yan
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Old 01-25-07, 06:06 PM
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Kinda similar situation for me. I really really want a swift, but the value of the DT makes it almost worth it to try and make it equivelant to the swift. So that's why I'm trying to explore the options of the DT.

**edit**
Looks like Yan answered the question about the fork. I couldn't find the original email I got from him.
As for why Yan suggested against changing the fork, I believe he said it would alter the geometry of the bike.

Last edited by big boy phil; 01-25-07 at 06:15 PM.
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Old 01-25-07, 07:25 PM
  #924  
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I have swapped forks between the Front Suspension model and the Non-Suspension model. I, too, was trying to make the Front Suspension model lighter for the "sporty" riding that I was using the bike for. The NS fork is about 1/4 inch taller, although i don't know about angles & such, but both rode fine. I've ridden them in the swapped mode for a while and am going to put things back as they were.

If you want to buy aftermarket forks for 20" wheels, you can try here:
https://www.gaerlan.com/bikeparts/frame/forks/fork.html

Originally Posted by John+++A+++
I was wondering the same thing. I would like to get the internal hub, but would try to shed as much weight as possible if I went that route, and the fork might be a part of that (anyone know how much difference it makes?)
-John
I haven't weighed the two, but it feels like a couple of pounds difference between the suspended fork and non-suspended fork. In other words, pretty significant in the context of bike weights. Also, the first thing one would do is to swap out the sprung seat, which has got to be around 2 lbs by itself.

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Old 01-30-07, 08:36 AM
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Has anyone ridden the IXNS or VIIIH in light-to-moderate wet weather - do the fenders work well or do you need a mudflap attached on back? Is a chainguard (chainguide?) needed to protect from greasy water flying on your pants?
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