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  1. #1
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    Trek 3500 upgrading ideas...stupid?

    I'm trying to figure out if I'll be throwing money in the toilet if I upgrade our 2011 Trek 3500 size xs (13.5 inch). I bought it new last year for my 12-year-old and I'm pretty sure he'll outgrow it sometime next year. As in the past, the plan is to hand it down to my daughter (she's 10) who will be tall enough in a year or two to ride it. So in total, the bike would be in service for a minimum of 4 years (and possibly much longer if my daughter doesn't grow much).

    It's Trek's lowest end mtb and all components are cheap and heavy (but work great). I recently changed the crankset to a cheap Acera one with lower gear ratios for easier climbing.

    My son is not very interested in mtb so he probably wouldn't care about upgrading. However, my daughter really enjoys coming to local trails with me whenever she can so I've been thinking about building or buying a nice bike for her in near future anyway. We do single track and small drops & jumps.

    I'm beginning to make a plan like the following:

    Wheels: I found a set of lightweight wheels for a very good price.

    Brakes: The stock 3500 is set up with v-brakes but the new wheels are for disk brakes. So I'll need new front and rear disk brakes.

    Cassette: Since the stock rear sprockets are freewheel (threaded) type so I need a new cassette to match the cassette free hub of the new wheels. I'm thinking about 10 speed 11-36t or something.

    Derailleurs & shifters: With the change in the cassette comes a new 10 speed rear derailleur. I'll have to replace the front derailleur too because I'm thinking about setting it up in 2x10.

    Fork: The stock SR Suntour is worse than a pogo stick. Rock Shox Recon 100mm, maybe?

    Does this plan make any economic sense? Except for the frame, I have a feeling that the finished bike would be better speced than the xc/trail hard tail offerings at around $1000, my estimate for the upgrading cost. The problem in buying a used bike is that it's a bit of challenge to find a frame in xs size. What do you all think?

  2. #2
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    No not stupid, I would leave the front derailleur as is though and just go 9 in the back. Keep the parts and put them back on when you need to get a larger frame and sell the old bike.

  3. #3
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    I'm interested in how this comes as I was considering a similar project.

  4. #4
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    Does the 3500 even have disc brake mounting locations on the fork and rear triangle? I know when I had one it didn't. May wanna check on that before you spend much more money. You may not even be able to use those wheels.

  5. #5
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    Well, it's kind of too late...

    Before I began parts hunting, I looked at major brands' 13 or 13.5 inch offerings in the $1000-$1300 range (the expected cost of the planned upgrades + the original bike cost). I was not too impressed. I also realized that decent hardtail bikes are sold mostly in 29ers, not a great option for a 5' tall girl (in a year or two..currently 4'8"). Weight is very important because she is not strongly built.

    So I reasoned that building up this 3500 bike and making it lighter wouldn't be too bad of an idea. If the frame breaks, we can always replace it with one of these affordable frames (Leader, Nashbar, Sette, etc.).

    So far we've made the following progress. The disc conversion wasn't too difficult. My LBS had a Gary Fisher mount adapter that fits the rear dropout perfectly.

    Frame: Trek 3500 13"
    Fork: Fox F100 RL
    Headset: stock
    Wheels: Specialized Roval Control AL
    Tires: Nashbar Nenor Traction
    Tubes: tubeless
    Brakes: Shimano SLX M666
    Rotors: Alligator Wind Cutter
    F. Derailleur: stock Shimano Tourney
    R. Derailleur: SRAM X9 Long Cage 9 speed
    Shifters: SRAM X7 3x9
    Cassette: SRAM PG-980 11-34
    Crankset: Shimano Acera 22-32-42
    BB: stock
    Pedals: stock aluminum
    Chain: SRAM PC-971 SP
    Handlebar: Answer Protaper Riser Carbon
    Grips: Specialized lock-on from my Stumpjumper
    Stem: Soma Shotwell 80mm
    Seatpost: stock
    Seat: stock

    Sorry I can't post the picture because of my post counts.

    So far $900 has gone into this bike, which is more than the upper limit of a kid's bike budget I can justify but I wanted to make it as light as possible. It weighs 25.7lb (including a bottle cage and a kick stand), down by 5lb from the stock weight. My daughter and I went for a short 3 mile ride with this new setup on a nearby single track today. She was very happy with the way the bike climbed. The frame is still a bit too big for her but she managed reasonably challenging climbs and descents at least as good as when she is on her regular 24" wheel bike. I think this bike will serve her very well for the next 2-3 years!

    Wait, this Trek is my son's bike and now we've transformed it into a reasonably expensive bike....We'll have to sort out who is going to ride which bike and when.

  6. #6
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    I'm thinking of upgrading my girlfriend's Trek 3500. It's a tank. It seems to weigh a ton compared to my bike.
    So basically switch out every part for some weight savings....
    Do you know what some of the best upgrades were to save some weight?

  7. #7
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    I upgraded my wife's old trek for my daughter. normally wheels is where to lose the most weight but I didn't want to put $ into new v brake wheels. I changed the saddle, seatpost, handlebar, stem (from a quill) and dropped some weight -don't remember the exact amount though.

  8. #8
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    Good to know someone else did this conversion as well. Was just thinking about doing this to my sons 2013 Trek 3500. I did do the fork last year. I picked up an older SID Race Dual Air for $150 and that dropped 2.5 lbs alone on the bike. Doesn't have lockout though. Even after that upgrade the bike still weighs 29 lbs though. See if I can get it down to under 26. It is a 15.5" frame.

    Need to find that disc brake adapter for the rear brake. I suppose the only option is mechanical disc brakes. Doesn't look like I can get hoses running to the back unless I zip tie them to the frame.

  9. #9
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    Quote Originally Posted by nmilsaps View Post
    I'm thinking of upgrading my girlfriend's Trek 3500. It's a tank. It seems to weigh a ton compared to my bike.
    So basically switch out every part for some weight savings....
    Do you know what some of the best upgrades were to save some weight?
    The best upgrade for a Trek 3xxx series bike is to replace the frame with any 4xxx series. This will drop a few pounds and reduce the harshness of the ride. The OP found the gears a bit too tall because the 3xxx series bikes are not really intended for xc trails. As a low-end (for trek) entry bike, they are meant to be used on bike paths and trails through relatively flat fields.

    You can lighten up the 3500 and she will enjoy it as long as you don't let her ride your bike. After all is said and done, though, replacing the 3500 with a 4xxx bike will be a cheaper route, and she will have a better ride.

  10. #10
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    Quote Originally Posted by Flamingtaco View Post
    The best upgrade for a Trek 3xxx series bike is to replace the frame with any 4xxx series. This will drop a few pounds and reduce the harshness of the ride.
    Then you might as well spend a few hundred on one of those cheap Chinese Carbon frames.

  11. #11
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    Quote Originally Posted by Flamingtaco View Post
    The best upgrade for a Trek 3xxx series bike is to replace the frame with any 4xxx series. This will drop a few pounds and reduce the harshness of the ride.
    At 3.5 lb on a 13.5" frame, the 3500 frame wasn't actually too heavy.

    To those who are thinking about upgrading the 3500 (or any entry-level bikes), the only reason I did this upgrade was because I couldn't find a bike in XS size with specs I wanted and at the price point I was willing to spend. You'd be better off starting out with a better frame if you are planning to spend more than a few hundred dollars on the 3500.

  12. #12
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    Totally agree with your Metol. The cheapest weight savings for me so far was that fork upgrade. I spent $150 on that older used SID and that shaved off well over 2lbs. Having a hard time justifying any weight savings with wheels. The stock wheel set that came with the bike is 2108 grams and that includes the skewer. Having a hard time finding a good price point on saving a pound with the wheel set. Only problem with the stock wheels is upgrading to different gearing and to disc brakes. Need new wheel set or hubs to do that.

    I haven't completely broken down my sons bike to find out what his 15.5" frame weighs. Have not bought the tool yet to remove the cranks. I do really want to change this out to a 2x9 or 2x10 for him before the end of the race season.

  13. #13
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    Stock tires on the 3500 are solid rubber. You can easily shave off 500-600 grams by putting on xc tires. The stock handlebars weight more than 1 lb. Another area you can save a lot of weight is the crank. The original crankset and BB together weigh close to 1300 grams. I got a great deal on an XT crankset and now the bike is down to 24 lb.

    The extent of upgrades on the 3500 bike really depends on your willingness to upgrade the wheelset. If your son's 3500 is like our son's, the rear hub does not have the disc rotor mount and is also a freewheel hub which is not compatible with cassettes. So the bike needs a new wheelset in order to use disc brakes and run a 2x9 or 2x10 drivetrain. The fact that we were able to acquire a 1600 gram wheelset for $120 was the deciding factor for us.

  14. #14
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    Was typing a reply just as you posted so now I have to change my reply.

    You read my mind about the wheelset. I figure that has to be the first thing decided on. I can't believe you found a 1600 gram wheelset for $120. That is the deal of a lifetime unless you look at this one. 2970 grams with TIRES.
    Crank Brothers Cobalt UST Tubeless Mountain Wheelset with Tires Blue - Wheels - Mountain
    But they are sold out now and that is a smoking deal on those wheels.

    So I am trying to decide on these wheelsets but I think all of them are not tubeless ready but I could put a Stan's Kit on them.
    Xero Wheel Pair Mtn Shawla 202D 26 8/9S Black - Wheels - Mountain
    Sun Ringle Ryde Comp 26" Disc Mountain Bike Wheelset MY12 Black - Wheels - Mountain
    I am leaning towards this one but I am not sure about using the Center Lock.
    Shimano WH-MT15 QR Centerlock Wheelset | Shimano | Brand | www.PricePoint.com

    I weighed his tires and tubes last year when I bought the bike.
    Front
    Tire 851 grams.
    Tube 171 grams
    Rear
    Tire 869 grams
    Tube 175 grams

    So that is about 4.5lbs in tire and tube weight.
    I use Racing Ralphs on my bike and those weigh in at 535 grams per Schwalbe's website. So yeah if I could get UST rims and go with a better tire I could easily save 2 lbs!!!!

    If you got a lead on some light weight tubeless ready wheel sets let me know.

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  16. #16
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    Quote Originally Posted by Metol View Post
    I got a great deal on an XT crankset and now the bike is down to 24 lb.
    I assume you had to change out the BB to use that crankset?

  17. #17
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    Quote Originally Posted by Metol View Post
    Brakes: Shimano SLX M666
    Are those hydraulic? If so how did you run the brake hose to the rear?
    The bike is really setup for cable guides and the hoses won't fit into those cable guides underneath the top tube.

  18. #18
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    Quote Originally Posted by Squashman View Post
    I assume you had to change out the BB to use that crankset?
    That's right. The weight saving from the crank and BB was about 215g EACH for a total of -430g.

    Quote Originally Posted by Squashman View Post
    Are those hydraulic? If so how did you run the brake hose to the rear?
    The bike is really setup for cable guides and the hoses won't fit into those cable guides underneath the top tube.
    Zip ties.

    As for the wheels, you should pay attention to the rim weight more than to the total wheel weight because the weight of the parts located farther away from the rotational axis (hub) has much greater effects on rotational inertia which affects climbing and acceleration. How about going the custom wheel route? You can know exactly how much each wheel component weighs. I've seen many good reviews about Merlin Cycles. You should be able to build a nice wheelset using lightweight rims and lightweight spokes/nipples under $300.
    Rear Handbuilt Shimano & DT Wheels - 26" - Disc | Merlin Cycles

  19. #19
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    Hi Metol.
    Looking at these handlebars. What do you think of these?
    Easton EC90 SL 635mm Low Rise Bar 2012 | Easton
    Going to assume I will have to change out the stem to use this handle bar as well as the Trek website says the 2013 3500 has a 25.4 stem.

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