Retrobike Forum Index

It is currently Fri Nov 16, 2018 3:59 pm

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 47 posts ]  Go to page Previous  1, 2, 3, 4, 5
Author Message
 Post subject: Re:
PostPosted: Fri Nov 02, 2018 9:51 am 
Old School Hero

Joined: Tue Aug 21, 2018 3:43 pm
Posts: 243
Location: Cambridgeshire - flatlands (the horror, the horror)
Rick you need I think to consider crank length. For the retrogrom’s hyperlight first bikes I made sure that he had 150 and then 155 cranks. Even 160 is a bit long for young ones, according to the latest understanding of the physiology of cycle motion. For the DH I went even shorter, cutting down some zee cranks to 142; highpath eng do this exceptionally well. But zees are heavy devils, and fine on DH but not Xc. So for a really nice set up I went for thorn cranks from sjs - 150s, and then 155s - and used a hope ti square taper B.B. and of course ti bolts - the cranks really are not that expensive from sjs and you get a nice choice of chain line using the highly adjustable line on the hope and the double ring setup on the thorn. We ran these 1x9 and then 1x10 which is fine for a young one.


Top
 Profile  
 
PostPosted: Fri Nov 02, 2018 10:54 am 
Retro Guru
User avatar

Joined: Sun Feb 08, 2015 8:51 am
Posts: 2255
Location: Macclesfield, Cheshire
I'm in total agreement with you, lots of options at 170mm, a few in the 150-160 area, but I'm working on something more like 120-130mm as my target.

Info I have seen recommends to aim for crank length 10% of the childs height so that should be about right for a 6-8 year old, perhaps even shorter than that if she fails to grow properly :D


Top
 Profile  
 
 Post subject: Re:
PostPosted: Sat Nov 03, 2018 12:30 am 
Old School Hero

Joined: Tue Aug 21, 2018 3:43 pm
Posts: 243
Location: Cambridgeshire - flatlands (the horror, the horror)
Rick that crank length sounds really sensible. Have you seen this?

http://forums.mtbr.com/families-riding- ... 32945.html

interesting even if you aren't into doing it. I used RS SIDs in 63mm format - then used discs so that I could run it with a 24 inch wheel. You could push them further and run with 20 inch wheels actually. White did a 24 inch air fork - wonderful thing - and you'd need to mortgage a small South American country to buy them...cost a fortune.

The Zokky Bombers which you have look v nice - fettled or original short format?


Top
 Profile  
 
 Post subject: Re:
PostPosted: Sun Nov 04, 2018 5:56 pm 
Retro Guru
User avatar

Joined: Sun Feb 08, 2015 8:51 am
Posts: 2255
Location: Macclesfield, Cheshire
Have seen similar but don't think I'd seen that particular one. Some great info there.

Wrt nodding forks, thought about it but decided against. I figured the difference from 26 to 24 is not worth the bother, and if using disc brakes it's not a problem for brakes. Lazy perhaps.

For 20inch wheel I could see the problem. Not for this project but I have a 20" kona makena that the boy used so intend to give that a once over. The forks were soft enough for kiddy weight so should be OK still but always handy to have a plan b.


Top
 Profile  
 
PostPosted: Sat Nov 10, 2018 11:33 pm 
Retro Guru
User avatar

Joined: Sun Feb 08, 2015 8:51 am
Posts: 2255
Location: Macclesfield, Cheshire
RickTheUncivil wrote:
Impulsive and possibly ill-thought-out buying has happened :D details to follow once they arrive but for now let’s say we are using 32H rims which won’t support a rim brake


Not 100% on these, heck I'm barely 50%, but hey, sometimes you just got to roll with it.

Not super light but lighter than many. Colour is, well, colourful and plays nicely with the pink frame. And they were a fricking steal.


Attachments:
spank1.jpg
spank1.jpg [ 43.9 KiB | Viewed 72 times ]
spank.jpg
spank.jpg [ 45.05 KiB | Viewed 72 times ]
Top
 Profile  
 
 Post subject: Re:
PostPosted: Sun Nov 11, 2018 12:59 am 
Retro Guru

Joined: Tue May 23, 2017 2:29 pm
Posts: 355
Nice.


Top
 Profile  
 
PostPosted: Wed Nov 14, 2018 2:26 pm 
Retro Guru
User avatar

Joined: Sun Feb 08, 2015 8:51 am
Posts: 2255
Location: Macclesfield, Cheshire
progress update.

Some rims in the box now and a choice of hubs so making good progress in the wheel department.
Or is it?
Black hubs because nice and tidy plus black forks, green rims because why not. Can’t decide whether to use silver spokes or whether I should go for black there too. Hmmm, that’s such a little problem I can barely type it out.

Moving on from colour onto patterns and numbers of spokes, I have seen some interesting threads around the web about lacing 32H hubs / rims with 16 spokes. Certainly for the front wheel there seems to be a reasonable case for saving a bit of weight by dropping the spoke count. It’s a small diameter wheel and the rim is strong so don’t have to worry too much about flexing all over the place, and no rim brake to worry about even if it is a little flexy. Plus remember we are talking about a kids bike here so light weight rider, light use.

couple of examples stolen from the web:

Attachment:
spokey1.jpg
spokey1.jpg [ 176.73 KiB | Viewed 27 times ]


Attachment:
spokey2.jpg
spokey2.jpg [ 92.34 KiB | Viewed 27 times ]


Advice seems to be that a crossed pattern rather than radial is essential but beyond that theres lots of guesswork and reckoning.

Never done it before but I’d be interested to hear any experiences along these lines.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 47 posts ]  Go to page Previous  1, 2, 3, 4, 5

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 9 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group