Bmx mini project

Who are you (no off-topic talk please)

Moderators: MrCurrieinahurry, maxim809, Moderator Team

Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

Here we go. My kids are 2 and 5. Current bike: mostly stock redline flight mini

I want to build a lower 9 pound bike. I will list parts on my next post which I have on order with weights.

I currently have an FMF mini frame which I cut the seat rail out and plan to glue in the uni seat. This as we stand sits as a bare frame with all paint removed. I purchased the bike hoping I could get it under 2 lbs frame weight. This did not happen. It weights 2lbs 4 ounces. Or 1020 grams. I plan to order a custom titanium frame tomorrow. 1lb 10 ounces or 737 grams. We will use the fmf frame once I order all of the lightest parts needed. We will stick with the redline for practice until I get wheels brakes forks headset and tires/tubes or sewups if I can find them.

We have box carbon mini handlebars and a box carbon/titaium BB 113mm

Please if anyone has any suggestions on light weight parts let me know.

bombertodd
Posts: 443
Joined: Tue Jan 22, 2013 6:23 am
Contact:

by bombertodd

Do you have a list of parts you're thinking about? It might help others find parts that are lighter than what you have planned/found. Usually super light bikes are in the details. Shaving a few grams from each part will add up (cost and less weight!!!).

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

Parts I have been thinking about:

Answer alumilite wheelset: 1080 grams +/-
Snap crank halves 145mm
Box xs mini carbon forks: 354 grams
Bombshell ridea brake lever 40 grams
Bombshell 686 mini v caliper:82 grams
Titatium brake caliper mounting points to the frame
Box concentric brake cable kit: 74 grams
Odyssey ghost pads: 28 grams
Elevn sealed standard headset:91 grams
Aest mtn bike pedals titanium spindle: 170 grams/pair
Primo semi slics: 162 grams each
ITS light weight tubes: 112 grams/pair


On order:
Kmc x9 chain
Box light weight seat clamp
Redline microline stem
Uniseat


I need to find a 1" carbon compression cap with aluminum machined bolt any ideas?

Any ideas on a lighter wheelset? Or tires/tubes or where to find sewups for minis?

bombertodd
Posts: 443
Joined: Tue Jan 22, 2013 6:23 am
Contact:

by bombertodd

Aest has a magnesium bodied pedal that weighs 156 grams. Lightest pedal I'm aware of.

You can add titanium hardware to the brakes, seat clamp, stem, etc...


I thought I've seen lighter Cane Creek headsets.

dogg
Posts: 291
Joined: Fri Jan 03, 2014 7:37 am

by dogg

just an fyi Ghost Pads are absolutely TERRIBLE they make a load of awful screeching noise and stop working effectively after not much time at all (regardless of the manufacturer claims) i ditched mine after only a few days. albeit this information is coming from someone who rides street and park on a nearly 30lb bike.

Intense Micro Knobbies are an excellent light weight tire as well, my friends have had fantastic luck with them on the race track.

Blue6 bolts used to offer tons of ti hardware but have gone under now, although i often see their products pop up on web classifieds now a days

xnavalav8r
Posts: 2594
Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

Some good info here.

http://weightweenies.starbike.com/forum/viewtopic.php?f=14&t=70171&hilit=bmx+junior

My 4 year old with his micro-mini. We didn't go with the lightest possible build as he is just learning to ride.

https://fbcdn-sphotos-g-a.akamaihd.net/ ... 2061_o.jpg

Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

That is some good information on the other post. The aest pedals are a gamble. My kid weights 45 lbs so I think I can gamble on the weight. Possibly the mag bodied pedals will work. I need To find a 1"head tube compression cap/alloy bolt.i also need to find some sewups. Tofu makes a tire that is 100grams each. I just need a wheel to put them on. Can I put them on any wheel like an alumilite wheel? Or do they need to be a special wheel? Also now to find 16 spoke fronts and 20 spoke rear? Any suggestions? Answer alumilite are 28h. If I can use these wheels with sewups it would put me at 1275 grams total. Both wheels and tires. Any suggestions on if this is possible? I will be under 9 lbs if this is possible.

xnavalav8r
Posts: 2594
Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

I build my own wheels and used tubular (sewup) rims on the micro mini. They are special rims with no bead. You have to glue the tires on. They will not work with the Answer rims. Tires are tough to find. Make sure you verify the diameters of both rim and tire before purchasing. Most sewup rims for BMX are actually 19".

Be careful with the pedals. A full-size MTB pedal is pretty wide. Your child runs the risk of pedal strikes on corners. Unfortunately there aren't any real lightweight options among junior or mini pedals.

You should be able to find a 1" topcap at any bike shop.

Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

Ok, where should I purchase the rims. Also what hubs will work? 16h front 20h rear?

xnavalav8r
Posts: 2594
Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

I found the sewup rims and tires on ebay. They are vintage, 28-hole, Sun rims. I am not aware of any modern manufacturers still making sewup rims in this size. I used a 28-hole road hub up front but built it with 14 spokes, skipping holes in the rim and hub. On the rear, I used a 28-hole Alienation hub laced 2x on the drive side and radial on the non drive side. To save weight I only used 7 spokes on the non-drive side so it is a 21 spoke wheel. The tires are Panaracer which I also found on ebay.

Here is some info on vintage sewups...

http://www.bmxsociety.com/topic/57550-20-sew-up-tires-rims/

xnavalav8r
Posts: 2594
Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

Here are some photos of the rear wheel I built for my older son's bike. Same lacing pattern and hubs but with a standard rim (Alienation Anklebiter). I don't have a closeup of the front.

Image

Image

Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

Thanks for the info. I will look into it. I most likely will go down the answer alumilite with primo slic tires route. I need to learn more about lacing wheels. I could always go the sewup route later on. Even with those wheels I can get close to 9lbs. Going with sewups would get me under 9 lbs

bombertodd
Posts: 443
Joined: Tue Jan 22, 2013 6:23 am
Contact:

by bombertodd

Have you replaced any of the steel bolts with titanium bolts?

Ryanperrymotorsport
Posts: 9
Joined: Wed Jan 01, 2014 7:01 am

by Ryanperrymotorsport

Every bolt on the bike will be either titanium or alloy

xnavalav8r
Posts: 2594
Joined: Mon Jan 21, 2008 12:09 pm

by xnavalav8r

I think you will be close to your goal without going crazy. My son's Junior XL was 11.5 pounds at it's lightest and I didn't make any crazy modifications. If I had broken out the drill and chosen a few lighter components I am sure I could have gotten closer to 10 pounds. But my son has some sponsor obligations so the lightest parts weren't always an option.

I'm a firm believer in keeping the power to weight ratio as high as possible, especially for little kids. But, not being an engineer, I choose not to take the chance of modifying parts which might lead to failure and risk injuring my kids. The same with alloy bolts... be careful where you use them. I'll go crazy on my own bikes, where I make the choices, but not on my kids' bikes.

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



Post Reply