need to put my kids new 27.5 on a diet.

Discuss light weight issues concerning mountain bikes & parts.

Moderator: Moderator Team

Post Reply
cruxarchd
Posts: 2
Joined: Tue Aug 23, 2016 5:08 am

by cruxarchd

Hello all. I am looking for advice on how to lighten up my 10yo daughter’s MTB. It is a new 2014 xxs Rocky Mountain Fusion 27.5. I got a great deal on it, but its a bit on the heavy side at 29.54 pounds. My daughter should have it for a while, so I am willing to spend a little money on the bike. My goal is to get it to around 25 pounds, which is where my bike and her mom’s bike is.

I am totally new to this, and am of average mechanical skill and knowledge. I have not torn it down to weigh a bunch of parts, but the specs are here: http://www.bikes.com/en/bikes/sport-tra ... usion-27-5

I did weigh the front wheel (alex td26 with shimano rm35)/tire combo and it was 2.070kg. For contrast, her mom’s (tubless) front wheel equivalent is 1.7kg.

The seat and post are definitely heavy, but I am not sure how much can be saved there.

The shock is the rockshox xc30, also heavy.

She is 4’11” and has a 29” inseam. I am not sure if the cranks are appropriate, so may consider replacing the cranks(Shimano Deore 170-175mm 44/32/22T 9spd) and cassette (shimano hg-20-9spd)

Any specific suggestions would be appreciated.

Thanks!

TheRookie
Posts: 926
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

Replace the heavy stock wired bead tyres with folding, will save at least 100g and get a better tyre. Those tyres are circa 700g, my Schwalbe (Nic/Ron/Ralph in 26") are sub 500g.

Go tubeless or at least go to lightweight tubes (a not to pricey lightweight from Schwalbe or Continental will save 60g over a stock 200g tube).

Attention to detail can save a lot for little money, for example you could just cut down the seatpost to get 100mm insertion and then replace with a better (lighter) post. when she grows.

Replacing the fork with an air fork with alloy stanchions will save over half a KG. Something like an XC32 gold or Suntour Epicon/Epixon.

1x gearing will save you over 300g but may not suite the intended usage due to loss of gear range, but if she can do all her riding on the middle ring you have the answer!

A better saddle with Cro-mo rails will probably shed nearly 100g and she may well need a narrower saddle anyway.

Foam grips are an easy way to save 50-60g (KCNC or Ritchey WCS).

Alligator lightweight brake discs will shed nearly 100g an end
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

by Weenie


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

www.starbike.com



stormur
Posts: 1173
Joined: Tue Aug 12, 2014 3:50 pm
Location: FIN

by stormur

@TheRookie : You still compare 650b to your 26"... Weights are DIFFERENT for different sizes.

Conti "normal" 650b tube weight 240-250g, going light tube/ tubeless saves over 100g on each wheel.

Another thing is question "is it worth it" ; apparently ALL there is heavy ( it's 500€ bike ! ), and upgrading every element is hard to justify financially. Result will be very expensive and very weight-disappointing. Any tuning has sense with good base- here I can't see any.

Change of post, saddle, bar/stem will save few hunderd grams. On certain bike size to loose is 4kg approx to get it "reasonably" light.

Numbers ( just examples from memory, for quiet light but still not draining to much wallet stuff ) :

3t post / stem/ bar : 220-250€
Wheels + tires : 350€
Saddle : 120 €
Drivetrain : 350€
Brakes : 250 €
Pedals : 100€

If you want REALLY light ( not extreme, still "wallet almost friendly" ) : double it . You'll save few hunderd grams again... .


Did it already crossed 3 times bike initial price ( 500€ ) ? ;)

If you want light : buy light or build light from scratch. Otherwise you'll get not so much for your €ffort. Base is wrong for it.
Go to Heaven for the climate, Hell for the company.
Mark Twain


I can be wrong, and have plenty of examples for that ;)

joeg26er
Posts: 122
Joined: Thu Aug 28, 2008 3:40 am

by joeg26er

There are plenty of lightweight budget parts available

For example - ashima Ai2 rotors are $26 / pair and would take off about 100g per end as was said already
You can find used 27.2 tires folding bead possibly get them as cast offs from bike shop upgraders? Ebay also - lose 700g (assume stock tires are 900g each)
$20 for pair of lighter tubes- lose about 200g total
so already at 1200g loss and less than $50 spent

Light saddle- Tioga Spyder copy from ebay? Prob lose 150 to 200g from stock saddle

Kalloy UNO ASO25 stem 80g for shortest version prob lose almost 160g from stock? $25

so now at 1560 g lost

kcnc skewers $50 lose 100g or more or can use Dixi MTB are cheaper and hold up to 150lb adult use

1660g lost $125 spent

Generic carbon seatpost 175g - $20 lose at least 200g

1860g lost $145 to $200 spent

boom - your bike is now 25 lbs if I added that up correctly?

you can add generic carbon bars or ebay used RaceFace ALU and cut down to lose more grams
yes- change grips to 20g each foam - $10, lose 100g from heavy stock rubber

oh yeah, cut down carbon seatpost - another 30g lost

possible to find Used Reba or SID 29er fork which can fit 27.5 wheel - about $300 BOOM nearly 1300g lost there (Suntour XCT forks weigh 2790g)

TheRookie
Posts: 926
Joined: Wed Jan 18, 2012 4:23 pm
Location: Midlands, United Kingdom

by TheRookie

stormur wrote:@TheRookie : You still compare 650b to your 26"... Weights are DIFFERENT for different sizes.


No sh!t, that's why my weight saving was based on 27.5 and I gave the numbers for my 26" and made it clear they were that size just as a guide.
Impoverished weight weenie wanna-be!
Budget 26" HT build viewtopic.php?f=10&t=110956

stormur
Posts: 1173
Joined: Tue Aug 12, 2014 3:50 pm
Location: FIN

by stormur

joeg26er wrote:There are plenty of lightweight budget parts available



If you consider "generic" carbon parts from China- it can be worth it, IF using "generic" is worth it at all ;)
Go to Heaven for the climate, Hell for the company.
Mark Twain


I can be wrong, and have plenty of examples for that ;)

cruxarchd
Posts: 2
Joined: Tue Aug 23, 2016 5:08 am

by cruxarchd

Lot to go on here. thanks for all the ideas. I'll spend some time researching these parts. Stormur, are you suggesting I not bother? I am not sure I understood your post.

Thanks.

bikewithnoname
Posts: 1733
Joined: Tue Sep 22, 2009 1:29 pm
Location: Paris

by bikewithnoname

I agree with stormur on this, you can end up spending 3x the current value of the bike upgrading it to make it lighter, it might be more cost effective to just buy a bike that is 3x as expensive to start with.

That said there are some changes you can make that will make it lighter and actually better to ride, good folding tyres and lighter tubes or tubeless are the obvious candidates. I might also consider a crank upgrade as if you get something like a race face you can carry that crank on to her next bike when she out grows this one. Other than that I'd probably get a carbon post which is lighter and often more comfortable (again this may be transferable to the next bike) and a lighter saddle, but saddles are very much a personal thing, if she likes the fit then keep it.
"We live in an age when unnecessary things are our only necessities." Oscar Wilde

joeg26er
Posts: 122
Joined: Thu Aug 28, 2008 3:40 am

by joeg26er

I don't suggest buying better wheels and cranks, you might as well buy an upgraded bike.

Most of us have cast off parts so throw some of those on there and some strategic weight loss parts as I suggested. If she really loves riding in a few years, spring for a better bike :)

joeg26er
Posts: 122
Joined: Thu Aug 28, 2008 3:40 am

by joeg26er

Actually, you could pick up a set of hi-end tubeless 26er wheels that someone is getting rid on on ebay or local shop complete with tires and BAM you have a bike better suited for her height and Lighter to boot :) Probably lose 4 lbs right there.

Personally, I picked up a set of notubes 26ers for a song and included EVO RRons.

by Weenie


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

www.starbike.com



User avatar
Getter
Posts: 848
Joined: Sat Nov 14, 2009 6:30 am
Location: So Cal

by Getter

Not sure how deep you really want to go. It can be an endless money pit. As some guys mentioned...replace enough parts...you might as well get a new bike.

Build up a nice set of wheels. You can build up a reasonably light pair for not too much money. Wheels + lighter tires should lighten up the bike bike by a decent amount and actually make a difference in the way the bike rides. If you do go that route make sure you get hubs that have convertible axles so if you plan on moving it to another frame that may have a different axle standard.

1x, like others mentioned too...but you need to make sure that she can push the potentially higher gears.

Post Reply