XCSKIBUM

I just receved a WOOM 4 (20") for my 8 yo granddaughter & I'm looking a year of so ahead for when my 6 yo grandson will be big enough to take over the WOOM 4.

I like the WOOM 5 (24") & I think it will be an easy change for Kennedi in a year of so after she gets used to riding trail, shifting gears & riding from a seat position that gives her maximum effeciency on the crank. The thing is I want to transition her to a suspension fork & all of the WOOM bikes are spec'ed with a 1" steerer tube.

Here's the thing. The WOOM 4 appears to have a 1" threaded steerer tube W/a clamp on stem. The funny thing is, the head tube on the 20" WOOM is by far the largest O.D of any of the 5 bikes in the garage that include a Specialized Crosstrail and Ariel Sport, a Kent Full suspension 26" MTB and a KHS factory XC racing frame build-up.

Here are the O.Ds of the various head tubes. All but the WOOM have 1 1/8" headsets.

Specialized Crosstrail/Ariel Sport....1.635" (probably 41.5mm W/paint)
Kent full suspension Mountain Bike..1.645" (41.7mm W/thicker paint?)
KHS XC Racing frame build-up........1.768" (44.9mm)
WOOM 4 20" Kids" Bike.................1.835" (46.6mm)

Given that the head tube of the WOOM has such a large O.D., at least 5mm larger than the Specialized frames, it seems like it would be a simple matter of machining a bushing to adapt a standard 1 1/8" threadless headset.

What is the normal O.D of the cups for a standard 1 1/8" headset?

mstateglfr 

Why would you need to put a kid under 10 on a suspension fork unless they are riding on technical mtb trails?

You mentioned low weight in one of you 19 other threads as a benefit of the Woom bikes. A suspension fork will add weight and little benefit. A 9yo doesnt need suspension to ride paths and trails. They especially dont need a cheap and heavy suspension fork...which is what is on most kids bikes.

XCSKIBUM

Ahh, if you read my post & actually took the time to understand it before you jump to conclusions, you would not even have to ask that question.

I'm looking ahead to the next purchase of a 24" WOOM 5. As soon as my 5 year old grandson grows into the WOOM 4, I will need a bigger bike for my granddaughter.

While our rides are not necessarily "technical" there are are lots of tree roots & large cobble filled wash-outs on abandoned RR grades.

They are very uncomfortable W/O at least a suspension fork. If my then 10 or 11 year old wants to keep up, an air suspension fork like an RST F1ST W/a lock out won't add much weight to an already light bike.

After all, the less the frame/drivetrain weighs, the less the all-op weight will be once the 1600 gram suspension fork is added.

A 19# 3oz 24" (W/the factory steel fork) WOOM 5 W/the 1600 gr RST F1RST will still be as light, (22#?) perhaps lighter than the 20" Diamondback W/the rigid fork.

You mention "cheap heavy suspension fork...which is on most kids bikes". Well, you have perfectly described the motive for doing what I am pondering.

I can do the combo I described for about $650. If you can point me to an air suspension fork (W/lockout) 24" kids bike that has components as good as the WOOM 5, weighs in at around 22#, for that kind of $$$, I'm all ears.

XCSKIBUM

OK, I pulled the stem. The collar on top is held in place by 3 set screws.


Seems that it is threadless yet not the usual scenario. There is no star nut or bolt to pull down on the bearings. You can see right through the steer tube.


The bearings are similar to what I have seen in 1 1/8" threadless.


I think the difference lies in the (inner?) cups/ball races. The cup in the frame (as well as the bearings) will pass a 1 1/8" tube. It measures 1.18" I.D.

I didn't have time to make a tool to drive out the cup to measure the O.D. but it has close to 1/8" per side (in addition to the 1.18 I.D.) in the head tube. It is @ least 34 mm I.D., perhaps more. Anyway, it looks like a 1 1/8" headset will fit.

As previously mentioned, the collar on the top is held in place by 3 set screws. I left a gap under the stem & used a wood wedge between the stem/collarunder each setscrew to pre-load the bearings before tightening down the set screws. Once that was done I set the stem tight against the collar & tightened the pinch bolt.

Sidney Porter

Assuming this can be done what is it going to do to the geometry?

All of the major bike manufactures make kids hardtail with suspension shocks in a 24 inch wheel. I would buy one of those if the trails require it. Rather than taking a woom and making it into a mtb.

XCSKIBUM

As long as the axle to crown length & trail are similar it won't change the geometry significantly. I have contacted WOOM & they suggested I look for a used 2015 WOOM SUPRA 5 that has a 1 1/8" headset. They made no mention of geometry problems.

Of course they said that their "propitiatory" headset won't allow a 1 1/8" steer tube, but that was expected. I need to ask some more specific questions in my next e-mail.

Your post motivated me to look into what the major manufactures have to offer. All of the bikes with quality components are full fledged mountain bikes with hydraulic disc brakes, 24 speed gears & weigh 25 to 28#. Worst of all, they all have crappy forks.

I'm not trying to make a "mountain bike" out of the WOOM, rather a light weight XC bike that will be comfortable over roots & cobble.

If I could get someone in Canada to buy a Ghost Powerkid 24 from MEC ($400 USD) that would be an option as I could still swap out the crappy RST Cappa fork for the RST F1RST and still be in the <$650 range. I live 13 miles from the border & have a friend in Ottawa. It will still be heavy though. That same bike is $599 @ REI.

mstateglfr 

Perhaps throw some larger tires on the Woom 5? Get some 2.1" tires to replace the 1.5" and let the kid ride. Its roots and cobble...I ride roots filled dirt paths with 1.9" tires on a rigid fork all the time. You let some air out and go.
Or perhaps find places to ride that arent filled with roots and cobble?...like a paved trail.


As for MEC, can you not just drive up there and buy the bike? Take your bike, do a small ride up there, then head on back stateside with the bikes. There is something like you can get $800 of merchandise and no pay anything if you are in Canada for a weekend(a couple days or few days?).
Regardless, ride the bike, get it dirty, and come back. You went up for the ride and are coming home now.
...or am i missing something?

XCSKIBUM

I ride the trails that are in my immediate vicinity. Restricting it to paved or smooth trails will greatly reduce the variety & we see a lot of wildlife on the more primitive trails. I don't feel that riding roads is safe for the kids unless it is in a park or campground.

MEC is a members only COOP & you have to be a Canadian citizen.

mstateglfr 

Yeah, i knew MEC is members only, but had no idea you also must be a citizen of Canada. Good lord thats restrictive for a retailer.

XCSKIBUM

I think it's actually a resident of Canada, not necessarily a "citizen". Probably a customs/duty sort of thing.

Viich

I believe that it is a requirement of their corporate structure, ie type of co-op, that gives them some significant advantage.