Search for a folding donor bike part 2

[Shahmatt]

And this length..?

Thanks John,

Can anyone tell me this length as well?

That is, the longest possible length at which the wheel can be mounted away from the donor fork. This is so that I can check if the wheel spokes have sufficient clearance to the donor fork after mounting. I'm only hoping that trail is not compromised too much at this length.

 

[Ivan]

Shahmatt, if you check

Shahmatt, if you check typical 130-5mm hub specs you will see the flange width, where the spokes connect to the hub is around 55mm (each model are different) so much less than a 75-80mm narrow fork. Of course in a rear hub this is offset towards the non-drive side. In your diagram you draw the spokes starting near the edge of their hubs which they don't. The non-drive side has the potential to be more problematic for you. They typically start about 25mm from the edge of hub. Try drawing the diagram with some of these input...

 

[jimbo3b]

Link to the Nexus 7 product page

Ivan is correct. It depends on the hub that comes with the Flamingo, but for example, the Shimano Nexus 7 has a flange width of 54.6 according to the manufacturer:

http://www.shimano.com/publish/content/global_cycle/en/us/index/products/0/nexus/product.-code-SG-7R46.-type-..htm

 

[Shahmatt]

Ivan and Jim,
Yes it looks

Ivan and Jim,

Yes it looks like the hub width is doable. Also maybe the bracket can be fixed by bending those upper arms (based on John's suggestion).

A new issue is that I may be adding a substantial amount of trail by fitting the bracket. Based on my post on the "Conversion Kit Brag Board", the bracket length ranges between 100 to 120mm. Based on images I'm estimating that the bend in the donor bike fork causes the dropout to trail by about 30mm. That means that the bracket may be adding approximately 40mm of trail (100mm - (30mm x 2)). The bracket may not work so well on this 16" wheel as it was designed for perhaps larger sizes.

Anyway, I will go ahead with this donor. Enough of the criteria are satisfied that I can at least try. Worst case situation I will list it up again for resale.

 

[John Tolhurst]

Short fork have less rake, or

Short fork have less rake, or offset. So when turned around the bracket should be fitted with the closest hole possible, to ensure some trail remains. Avoid pushing the wheel forward into negative trail regions.

 

[Shahmatt]

The following geometry


The following geometry calculations were based on some side-on images of the donor.

The original trail of the donor. About 1.2".

Now imagining the fork turnout around 180 degrees. A trail of around 0.6".

Do the lines I've drawn seem correct? I'm not sure, just working on stuff I've read on the internet here.

What is an acceptable trail? I read that for motorbikes a trail of 4" to 6" is good. If that's the case then the default trail on the donor seems really low.

 

[John Tolhurst]

This will be ridable. 
The

This will be ridable.

The method of showing the resulting trail is correct, but working from a picture means making assumptions about perspective distortion.

 

[Shahmatt]

I understand that there may


I understand that there may be some inaccuracy because of the way the photo is taken. But I guess I can be more optimistic about the donor now.

Thanks very much for your help. I plan on ordering the kit early January since I am on holiday for the rest of this month and won't be around to pick up the package when it comes. I hope stock is available!