Results 1 to 9 of 9
  1. #1
    Big air wannabe
    Reputation:
    Join Date
    Oct 2008
    Posts
    67

    BMC TF 2.0 Stem Length

    Starting a new thread as our other BMC threads are getting too long.

    For the last two weeks I've been running a 110mm stem on a 17" TF 2.0 (I'm 5' 9"). It seemed fine but my back began aching and today I noticed my arms were fully stretched out to reach the bars in my typical riding position. I tried my two other bikes (one hardtail, one road bike) and found my elbows were bent on both.

    So I installed a 45mm stem that was lying around and went for a ride. It felt much better, DH and jumping were much easier. I did not try XC but controlled Endos are harder (practicing them with side kick-outs to improve my balance/ bike control).

    Summary? When sizing the stem if your arms are not at least slightly bent then try a shorter stem. I am ordering some cheap stems a few sizes in between as 45mm is probably little short for XC.

  2. #2
    mtbr member
    Reputation:
    Join Date
    Feb 2005
    Posts
    451
    I initially ran a 90mm stem on my TF, which felt fine and was slightly shorter than my XC hardtail.

    Then i tried a 75mm stem to really tighten up the cockpit, and as you've pointed out, felt fantastic on the downhills and in the air - nice and manouverable.

    However, i think handling wise, for me its more the height of the handlebar thats the issue, as oppose to the length.

    I've learnt to get the length so its comfortable and you have a wee bend in your elbows, and then tune the height of the handlebar to get enough weight over the front of the bike without feeling sketchy.

    BTW, 45mm is really short!
    Though my mate rides his 19inch Chameleon with a 50mm stem on it, and he loves it, so who am i to say what works and what doesnt!

  3. #3
    mtbr member
    Reputation:
    Join Date
    Jan 2009
    Posts
    145
    I think I may start shorter and then get a longer one if I need one. It seems like a long stem would put your weight too far forward because of the steep head angle, making downhill and landings pretty sketchy.

    Does the bike feel super twitchy with the short stem on it? I'm thinking of running somewhere around 50mm.

  4. #4
    low speed, high drag
    Reputation:
    Join Date
    Jan 2008
    Posts
    317
    I did my first little street ride today. Feels great having rear squish! I'm 6' tall and the 19 feels perfect. Handling feels good with a 130mm fork and wide bars. The HA is definitely a tad bit steep, more so than my hardtail, but I can't really feel a difference to be honest. The only thing I'm concerned about is the QR clamp. The seat only stays if I tighten it to where both sides of the collar are practically touching. Does that sound off, or am I just being paranoid?

    Edit: Just realized my old seatpost was 30.9mm. Oops
    Last edited by Ouroboros; 02-28-2009 at 12:41 AM.

  5. #5
    Big air wannabe
    Reputation:
    Join Date
    Oct 2008
    Posts
    67
    Quote Originally Posted by Little Willy
    I've learnt to get the length so its comfortable and you have a wee bend in your elbows, and then tune the height of the handlebar to get enough weight over the front of the bike without feeling sketchy.

    Quote Originally Posted by Oregonism
    I think I may start shorter and then get a longer one if I need one. It seems like a long stem would put your weight too far forward because of the steep head angle, making downhill and landings pretty sketchy.

    Does the bike feel super twitchy with the short stem on it? I'm thinking of running somewhere around 50mm.

    These appear to be the trade offs. I had the 45mm stem on my hardtail (wife's bike) and the front wheel washed out twice on loose sweepers. At first I was confused as to why the new bike was doing that. Now I am now very certain that my weight was too far back for the front tire to get enough grip. The seat was as far back as possible so I'd fit 16" frame esp with the the 45mm stem. Of course with this setup any air time was easier - in fact I re-learned to jump on this bike. Long stems appear to do the opposite, terrible on landings with more chance of flipping you over to due more weight on the front, but I don't remember ever washing out a front tire before using the short stem.

    To me stem length does not appear to make the steering any quicker or bike harder to control on the ground (other than fast loose corners!)

  6. #6
    Big air wannabe
    Reputation:
    Join Date
    Oct 2008
    Posts
    67
    Quote Originally Posted by Ouroboros
    Edit: Just realized my old seatpost was 30.9mm. Oops


    With 130mm forks the HA will be a little slacker than 120mm.The Yeti 575 I almost bought drops nearly one degree for each 10mm travel increase so your HA is probably closer to 70 and 140mm closer to 69.

  7. #7
    low speed, high drag
    Reputation:
    Join Date
    Jan 2008
    Posts
    317
    I bought a new seatpost w/ correct clamp but I'm still getting a little slipping...I'm not using a torque wrench, but I'd say the bolts feel pretty tight. Anyone know of a simple way to make little grooves in the post? It's just a cheapo aluminum post from Performance Bike.

  8. #8
    Big air wannabe
    Reputation:
    Join Date
    Oct 2008
    Posts
    67
    Quote Originally Posted by Ouroboros
    I bought a new seatpost w/ correct clamp but I'm still getting a little slipping...I'm not using a torque wrench, but I'd say the bolts feel pretty tight. Anyone know of a simple way to make little grooves in the post? It's just a cheapo aluminum post from Performance Bike.
    Try the following in order:

    . Clean out the seatpost tube and post to ensure they are grease free
    . Try 'shimming' the post with parper - that worked for my carbon post
    . Try a friction compound recommend to stop carbon posts from slipping
    . Buy a Thompson post which has milled grooves in it

    I guess you could use a pipe cutter to put grooves in your post but if the post ever snaps off don't blame me

  9. #9
    low speed, high drag
    Reputation:
    Join Date
    Jan 2008
    Posts
    317
    Quote Originally Posted by mp3_e46
    Try the following in order:

    . Clean out the seatpost tube and post to ensure they are grease free
    . Try 'shimming' the post with parper - that worked for my carbon post
    . Try a friction compound recommend to stop carbon posts from slipping
    . Buy a Thompson post which has milled grooves in it

    I guess you could use a pipe cutter to put grooves in your post but if the post ever snaps off don't blame me
    That would be a bummer. I'll try all said advice, thanks. I've also heard, in some cases, simply rubbing dirt on the post can help. Some guy even made a shim with a beer can

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •