Bicycle Mechanics - Can't figure out what is slowing me down...
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I'm riding a SC Chameleon. I'm surprised at how slow this thing moves, be it on the roads or on the trails. I compare myself to my buddies in terms of speed. When we all get on road bikes, I'm the fastest (I ride a pos road bike, they're on entry level nice ones). When I was on a wally world mtn bike, I was faster or the same speed as my buddies on their entry level mountain bikes. On the Chameleon, I'm always holding the group back.
So, I think the three things I'm thinking that could be slowing me down are: the tires, the hubs, or the brakes.
Shimano M525 hubs
Avid Juicy 3's
I've been trying to isolate what it is that's slowing me down... When I spin the wheels on the bike, I can't hear any disc rub. As well, the tires aren't touching the ground. This suggests that it's perhaps the hubs (cones on too tight?).
I undid the cones and checked the hubs. Perfectly clean, adequate grease, everything seems okay. I put it back together with the cones screwed on by hand. Put it all back on the bike, and the wheels still seem to grind to a halt.
Is this typical of a bike with disc brakes? Do disc brakes grind away without making noise? I've had this problem since I got the bike. I thought it might be the discs rubbing, but I also thought that over the course of a few hundred km, I'd grind the pads away enough to allow it to spin freely.
Anyone have any ideas? I'd appreciate the input! :)
03-22-09, 01:26 PM
Wheels with good quality bearings should spin freely for a while if they're adjusted not too tight. Just tight enough to eliminate play. In some cases just the barest amount of play before closing the quick release is the goal, and that's what I try to use.
03-22-09, 01:26 PM
Can you feel any resistance, or does it just feel slow? The nevegals aren't super heavy at 630 grams(2.1), but also not lightweight. Some sub-600 gram tires might help a little. How long have you had the bike? Perhaps you're just not adjusted to it quite yet.
03-22-09, 01:32 PM
If you can see this "grinding to a halt" while the bike is on the stand or if you lift a wheel, try removing the caliper from engagement with the disk, and see if the grinding or slowing are eliminated.
If the wheel does not spin free on the stand, and the spinning is still bad with the caliper off the disk, the problem must be the bearings.
If the wheel spins free with the brake on, your bearings are ok as long as they don't have any play, and the poor coasting on the road is the tires.
03-22-09, 01:45 PM
FWIW, the Kenda Nevegal tire is highly recommended (two time winner of Mountain Bike Action tire shootout), so I think you can scratch that off the list of possibilities.
wow, this area of BF moves really quick. thank you for the quick responses!
Road Fan - does the amount of force you have to use to close the quick release matter? I didn't know that. Mine aren't super-super tight, but that might be something I should check out. I didn't think of removing the caliper to isolate the brakes-only issue. Call me a dummy. I'll check that out too.
Frankenmike - I'm riding with the 2.35" Nevs. I don't think the mass of the tire should matter - wouldn't that just increase inertia? It'd be harder for me to speed up, but not to maintain the speed. Theoretically the wheels should spin longer because of the tires being heavy, right? I've had the bike for a year. At the end of the season I had put about 500 or 600km on it. During the winter I did a bit of street riding, and so far this season I think I've done another 50km or so. Can't tell for this season - my comp's battery died.
Pacificaslim - I'm not doubting the quality of the tire. I agree, it's a pretty neat tire - I can climb vert with it (exaggerated a bit, but you know what I mean). I'm just wondering if it's what is slowing me down.
03-22-09, 02:53 PM
There are some bikes that simply won't go fast, or roll, like they should - and no one has come up with a suitable explanation as to why. One example of such bikes were the Shogun bicycles popular back in the 1980's. For some reason, non-mechanical, they simply felt/were tethered to the ground. Weird.
03-22-09, 04:14 PM
I know you mentioned cone adjustments, and yes... that can cause a _Major_Slowdown_... but...
You might want to count teeth... (not those.. the ones on the bike!)
Try to stay in a similar gear to your buddies. Check crank-arm lengths... if you are running 175's and they all have 170's, that'll make a difference over the course of a few hours.
I know this goes w/o saying but...... Riding off-road is very different from Road. Lots of grinding up hills and technical sections and spinning where you can... vice on the road where spinning is much more important than being able to grind.
FWIW...I've found that riding my MTB makes me stronger than training on my road bike. So, I just ride the road bike on the weekends and go really, really fast on it, and ride the MTB during the week to stay strong.
I tried loosening the quick releases a bit. didn't make a difference at all.
I know that riding off road is different from on road. It's hard to compare speeds off road. I happen to be much faster than my buddies off road, but I think that's a result of more off-roading experience than my buddies. However, on fire-road like trails and on the road where tech. skill is at a minimum, I am much slower than they are.
I'll take off the braking system, or the disc (disc might be easier to take off, actually), and see how it rolls like that. That'll narrow it down as to whether it's the hubs or the brakes.
I'll get back to y'all on this tomorrow.
03-22-09, 06:36 PM
At 780 grams, the nevegal 2.35s are quite heavy. We're talking over a pound of rotating weight over some sub 600 gram tires(I know I'm repeating myself). Lighter tires would make a huge difference, especially while spinning or climbing.
03-22-09, 06:46 PM
2.35 are huge man. Its not only the weight, more importantly...
It makes an oval contact patch across. The opposite of a skinny tire wich makes an oval contact patch lenghtwise. You want a round contact patch. 1.5 will get you close to a round one.
Go down to 1.95 and see for yourself. You don't have to buy, borrow your friends. It will increase your speed plenty and still give you a very comfortable ride.
1.5 will get you the fastest roll but its not as cushy as 1.95. less than 1.5 and you wont gain any speed at all, only make your ride harsher.
Good luck! Dont beleve me! Try it and see for yourself! You loose nothing but time.
Joshua A.C. New
03-22-09, 07:32 PM
Yeah, tires would be my first concern. Are you sure you're up to pressure?
Bearings could be shot, too.
03-22-09, 07:40 PM
There has been much research done on this:
Wider tyres roll faster off road than skinny ones and the only exception to this is if you are a very light weight rider... I am faster on 1.95's than I am on 2.25 plus tyres as the narrower tyre gets a little more bite.
My riding weight is 140.
Those 2.35's are gonna be sluggish on fire roads and hard pack... especially if the tyre pressure is lower.
03-22-09, 08:20 PM
On the next ride, after a couple miles, swap out with one of your buddies. Don't say anything to him (probably too late), just that you want to swap bikes and get his /her opinion
Frankenmike - I'm riding with the 2.35" Nevs. I don't think the mass of the tire should matter - wouldn't that just increase inertia? It'd be harder for me to speed up, but not to maintain the speed.
You're right about the inerta part, but are you taking into consideration the wide contact patch? That's a wide tire to try to go "fast" on. Lots of rolling resistance. There's also the question of your gearing. standard MTB 44/32/22? What cassette on the back?
Crank the pressure up to the max on the Tires. I run the 2.35 Nevs at max pressure, and let the suspension do all the work. I honestly think I am faster on my current bike than my previous hardtail or full suspension. But then again, the 120lbs no longer around my belly also helps that.
I weigh 130lbs (hah!). I ride with the nevs always in the recommended pressure range (30-50 psi), usually at 50 psi unless i plan on trail riding in damp conditions.
I'd riding 1x9, 32t up front, 11-34 in the back. I'm usually riding with the larger cogs in the back.
I was thinking of "upgrading" to a set of 2.1" tires... Schwalbe Racing Ralphs were recommended to me for my area by my lbs (expensive, though @ 80$ a pop).
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