Question on Downtube VIII fs as donor bike

O

ocd

Member
I have acquired a Downtube VIII fs (full suspension) as a donor bike (image attached). I like the idea of suspension to compensate for the 20" wheels, but I have a question: should I keep the front fork or switch it for a plain one? It would seem that having the give of the fork inside the drivetrain triangle would compromise its rigidity (though the Sofrider does just that).

Thanks,
ocd

downtube_viiifs.jpg
 
Charles.Plager

Charles.Plager

Recumbent Quant
Hi OCD,
Here's what I know:
-

Hi OCD,

Here's what I know:

- A lot of people have converted Downtubes into Cruzbikes with very good results. All of the pictures I've seen have been the non-suspended bikes (front or rear). (That i haven't seen any pictures is hardly conclusive evidence that it hasn't ben built before.)

- The conversion kit it meant to be used with a fully suspended mountain bike (with suspended fork). This to me suggests that you won't have any problems with the suspended front fork.

- I've been considering converting a Downtube where I was planning on trying the fully suspended bike. I'm very interested learning about your experiences.

Here's my opinion. Since you have suspended fork, try it first. If you find that it doesn't work well, then switch to a non-suspended fork (but I'm guessing you won't have any issues). If you do buy the unsuspended fork, I'll be very curious to find out your opinion on how they differences .

Please keep up informed and good luck!

Charles
 
Jerrye

Jerrye

Spam Slayer
Defjack has converted a Downtube

See this thread: http://cruzbike.com/can-i-convert-columba-bike-which-i-own
 
O

ocd

Member
Sensible approach

Charles,

What you suggest makes a lot of sense. I plan to follow your suggestion.

Jerrye,

From the pictures it seems that Defjack converted a non-suspended Downtube.

Thanks,
ocd
 
defjack

defjack

Zen MBB Master
   I did use the unsuspended

I did use the unsuspended but I think the suspended would work better. The suspended Downtubes have a longer wheelbase and the suspension should keep th wheels on the ground better when you are really riding hard. Jack
 
O

ocd

Member
Conversion kit on order

I have ordered the conversion kit. Thanks for all the suggestions.
ocd
 
O

ocd

Member
Useful youtube channel

The conversion kit arrived today. I have done the easy stuff: take wheels and pedals off, open chain, etc. I also took the cranks off which for me is medium hard. I am off tomorrow to get the tools to take apart the bottom bracket (certified tool junkie here).

BTW, I have found a very nice youtube channel with great tutorials on bike mechanics:

http://www.youtube.com/user/cjhoyle?feature=watch

In particular, I found the video on bottom bracket maintenance very useful:

http://www.youtube.com/watch?v=VXQA4kNmhPA&feature=plcp

Thanks,

ocd

 
Charles.Plager

Charles.Plager

Recumbent Quant
Hi,
Sounds like you're making

Hi,

Sounds like you're making good progress. Take pictures along the way so you can show us how you did what you did.

Keep on keeping up updated. I'm looking forward to seeing lots of pictures the final product!

Charles
 
O

ocd

Member
Bottom Bracket

Today I took apart the bottom bracket. The tools to disassemble it were a bit more expensive that I was expecting, though. The drive side did not give up without a fight (luckily, the video I pointed out in my previous posting on this thread warned that it is reverse threaded). A PVC pipe inserted at the bottom of the wrench provided the necessary persuassion. Next step is going to be installing the bearings and axle in the new bottom bracket. That might have to wait until Thursday or the weekend.

ocd
 
Charles.Plager

Charles.Plager

Recumbent Quant
Hi OCD,
As far as tools go, I

Hi OCD,

As far as tools go, I bought this Nashbar toolkit that has pretty much everything I've needed (crank puller, bottom bracket tool, etc). Currently $40 (and they have a deal that ends tonight for free shipping - they'll have such deals again as they have them often). I'd recommend this for people who want to play and need a little of everything. There are of course higher end kits that are worth considering as well.

Cheers,
Charles

p.s. For the bottom bracket, using a hair dryer or hot air gun (as recommended by Doug and Kim on this forum) work well. Just make sure not to melt any paint...
 
O

ocd

Member
Axle too narrow?

After a month, or so, hiatus I am back at the conversion. The delay was the result of a combination of the weather being too nice not to ride and work going a bit nuts.

This morning I finished step #21 in page 5 of the instructions, ending in "...fit them into the new bearing shell".

I skipped #22, as the tires seem OK.

I have a question on step #23: after cleaning and re-greasing the bearings I installed the long axle. Everything looks OK, but when I go to install the freewheel into the rear dropouts I have too much room: the space between the dropouts is 135 mm; the space between the two nuts (in the axle I have nut/spacer/cone/wheel/cone/spacer/nut) is 125mm. I am short 10 mm. I suppose I can make the difference with washers, but I am wondering if I have done something wrong. Also, is the drive wheel going to be too wide for the front dropouts?

Any help much appreciated.

Thanks,
ocd
 
O

ocd

Member
Turn the fork?

Item #27 (page 6) in the instruction booklet says "Turn the forks so they are pointing backwards." As you can see on the picture of the first message of this thread, my donor's fork is completely symmetric: i.e., turning it backwards makes no difference. I am assuming I can skip that step, right?

Also, perhaps I should read ahead, but I do not see how the front brake can operate. Does the conversion result in a rear brake only bicycle?

Thanks,
ocd
 
Charles.Plager

Charles.Plager

Recumbent Quant
Hi OCD,
I don't think the

Hi OCD,

I don't think the fork is actually symmetric when you rotate it around the stem. Even if it is, (and I'm guessing here so that that into account), I think the brakes will work better if the fork is turned around.

Take some pictures and post them. :)

Cheers,
Charles
 
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