Bicycling Off-Road

ooheadsoo · « **Reply #320 on:** 23 Mar 2010, 08:57 am »

Stock tires are 2.2". I assume this means a total bb height reduction of roughly 1.5". I believe the stock cranks are 180mm but don't quote me on that. The shock has minimal sag. My co-worker (avid cyclist) thinks I'm just being finicky. I will try my little mt. climb and if I really feel like I'm going to die from not raising my inside pedal in time while zipping down hill, I'll put the stock mtb tire back on the rear before I commit to the big apples on the rear.

PhilNYC · « **Reply #321 on:** 23 Mar 2010, 12:39 pm »

Assuming that you are talking about a 2.2" profile height, and your new tires have a 1.5" profile height, that would only result in a .7" height change for your bottom bracket...probably not enough to really change the pedal clearance as much as you're saying (as others have mentioned, shock travel or even tire pressure could have that much effect and shouldn't change your pedal clearance that much).

That said, 180mm is a very long crank, and not a length I've ever seen on a stock bike...is that common on a 29er? On 26ers, stock cranks are usually 170mm or 175mm...

Levi · « **Reply #322 on:** 23 Mar 2010, 12:44 pm »

I agree. 180mm is very long crank arm length. You must have long legs.

ooheadsoo · « **Reply #323 on:** 23 Mar 2010, 01:30 pm »

Yeah, the two of you are right. I don't know the length of the crank. There is no suspension sag to speak of, however.

PhilNYC · « **Reply #324 on:** 23 Mar 2010, 06:52 pm »

Maybe you can post a photo of the bike?

twitch54 · « **Reply #325 on:** 23 Mar 2010, 07:18 pm »

With regars to biking off road.....any 'Rails to Trails' riders in the group ?

jackman · « **Reply #326 on:** 23 Mar 2010, 10:11 pm »

Unfortunately there are very few Rails to Trails areas near my home. Argon Labs has some nice limestone trails but I haven't been there in a while. I need to dust off my MTB! I've been doing lots of road cycling lately (20+ miles each night for the past couple days and 40+ per day on the weekend) but I look forward to getting some trail riding in.

Guys, please post pictures if you have a chance. It's so cool to see some of the beautiful areas on both coasts where you guys ride! My area is pretty flat except for a cool mountain bike area in Palos and Oswego. I'll post pix the next time I go to a noteworthy place.

Cheers,

J

Don_S · « **Reply #327 on:** 23 Mar 2010, 11:28 pm »

Many crank arms are stamped with the length on the inside of the arm. If not, measure the arm from center to center. That is from the center of the bottom bracket spindle where it attaches to the arm to the center of the pedal where it attaches to the arm.

Quote from: ooheadsoo on 23 Mar 2010, 01:30 pm

Yeah, the two of you are right. I don't know the length of the crank. There is no suspension sag to speak of, however.

Levi · « **Reply #328 on:** 24 Mar 2010, 12:36 am »

For Shimano the lenght and model is stamped in the back near the spindle mounts.

ooheadsoo · « **Reply #329 on:** 24 Mar 2010, 01:16 am »

The crank is 175mm. Debating if I should try my usual route this evening...

I rode my usual route. I'm afraid to push the turns hard, but it's definitely doable. I only scraped the pedals once and it wasn't until I was already down the hill, so I think I will be able to live with this for a while, as long as I really pay attention to raising the inside pedal. The problem is when it's a medium speed corner, like at an intersection, and I want to pedal through it. That's when I'll forget myself and scrape really hard.

Levi · « **Reply #330 on:** 30 Mar 2010, 02:03 am »

I rode my bike this weekend and took several pictures. Just want to share how my bike looks like now.

Bemopti123 · « **Reply #331 on:** 30 Mar 2010, 02:09 am »

I must get my head checked out, as I find excitement even in the most mundane mechanical/metal creations. That is a sort of sexy, military looking bike, Levi. Good lookin'.

Mike Nomad · « **Reply #332 on:** 30 Mar 2010, 02:26 am »

Lots of good information on this thread. Thanks to all.

I didn't realize what is considered "long" for crank arm length. I'm using the stock cranks (Tru ATV ?) that came with my '08 Haro SS Mary: 180mm. The rims are 29" (stock), and I haven't had any problems...

Levi · « **Reply #333 on:** 30 Mar 2010, 02:35 am »

Thanks Paul for the military spec complement.

Mike, It all depends on your frame size. If you put your 180mm cranks in my bike 16.5" (picture above), you will definitely have problems with ground clearance in rocky trails.

jackman · « **Reply #334 on:** 30 Mar 2010, 03:32 am »

Quote from: Levi on 30 Mar 2010, 02:35 am

Thanks Paul for the military spec complement.

Mike, It all depends on your frame size. If you put your 180mm cranks in my bike 16.5" (picture above), you will definitely have problems with ground clearance in rocky trails.

True, and your knees will take a bigger beating. You can account for the crank length by adjusting your gearing but if your cranks are too big it will be difficult to ride with a high cadence and put more pressure on your knees. This is especially true in road cycling but MTB riders would have a similar problem when pedaling up hills. My cranks are 175mm but my next set will be 172.5 or 170.

Levi, cool bike. What is the deal with that front gearing? You have a triple pictured but the XTR on the bike appears to be a really small double. Is that something new? I've seen small rings on single speed bikes but your bike has gears. It looks cool but I've not seen that on other bikes. What's the deal?

Levi · « **Reply #335 on:** 30 Mar 2010, 03:57 am »

Hi Jackman, you have keen eyes. I converted my XTR and made it a 2x9. I then replaced the 42 tooth ring with a 34 bash guard. Most of the trails that I visit has lots of log jumps. I have plenty enough tall gear for the trails running 11-32 in the back.

ooheadsoo · « **Reply #336 on:** 30 Mar 2010, 08:11 am »

How are you standing the bike up in the picture?

PhilNYC · « **Reply #337 on:** 30 Mar 2010, 01:04 pm »

Quote from: Mike Nomad on 30 Mar 2010, 02:26 am

Lots of good information on this thread. Thanks to all.

I didn't realize what is considered "long" for crank arm length. I'm using the stock cranks (Tru ATV ?) that came with my '08 Haro SS Mary: 180mm. The rims are 29" (stock), and I haven't had any problems...

29er geometry usually has a slightly higher bottom-bracket height compared to a 26er, so you can put longer cranks on it...

PhilNYC · « **Reply #338 on:** 30 Mar 2010, 01:06 pm »

Quote from: Levi on 30 Mar 2010, 03:57 am

Hi Jackman, you have keen eyes. I converted my XTR and made it a 2x9. I then replaced the 42 tooth ring with a 34 bash guard. Most of the trails that I visit has lots of log jumps. I have plenty enough tall gear for the trails running 11-32 in the back.

Wow...I went the other way...I put a 48T on for my big chain-ring...!

PhilNYC · « **Reply #339 on:** 30 Mar 2010, 01:08 pm »

Quote from: ooheadsoo on 24 Mar 2010, 01:16 am

The crank is 175mm. Debating if I should try my usual route this evening...

I rode my usual route. I'm afraid to push the turns hard, but it's definitely doable. I only scraped the pedals once and it wasn't until I was already down the hill, so I think I will be able to live with this for a while, as long as I really pay attention to raising the inside pedal. The problem is when it's a medium speed corner, like at an intersection, and I want to pedal through it. That's when I'll forget myself and scrape really hard.

Fwiw, it's generally regarded as good riding technique to put the outside pedal down (and inside pedal up) on a turn...this puts weight on the outside and keeps the bike from sliding if you are going at higher speeds. That said, it doesn't help you much if you are pedaling thru the turn...

What kind of pedals are you using?