Bicycle Mechanics - Thank All Of You

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.
Paul Barnard
12-03-11, 07:44 PM
Over the past few months I have bugged you with quite a few questions. I had one prior build some 15 years ago and with your help I was able to turn picture one into picture two. It should make a good gift for 14 year old boy whose school colors are red and blue. I started with some take off rims and a box of odd parts I had laying around. I added a $40 Nashbar frame and some assorted parts I ordered. I am pretty happy with the outcome. I have one more to do, the next one for myself.
http://i55.photobucket.com/albums/g157/PaulBarnard/FritchieMarshandRedfish015.jpg
http://i55.photobucket.com/albums/g157/PaulBarnard/Hopedaleandholidays016.jpg
Beautiful. Looks nicer than what most stores out out. The color coordinated tires and radial front wheel make it really special, a great conversation starter.
Since perfection is considered bad karma in some circles, I'll point out the flaw. The rear brake cable loop is too long, trimming an inch or two would make a better run with less bends.
mrrabbit
12-03-11, 11:39 PM
Looks great...
1. Slide saddle back 1cm so that it is centered on post.
2. Swap to a 1cm shorter length stem.
You have just a tad of tilt-back of the saddle which is great - means you are not forcing your body to rely on the hands for support. (That leads to hand and wrist pain...)
Other than FBinNY's housing suggestion - looks good overall.
=8-)
Paul Barnard
12-04-11, 06:28 AM
Thanks for the pointers. Once I give it to him I'll make the final fitting adjustments. I still don't have the rear derailleur dialed in perfectly. I cant seem to get it just right in second gear. It clicks and jumps a little. First is better but not perfect. 3-8 work flawlessly.
HillRider
12-04-11, 07:43 AM
Thanks for the pointers. Once I give it to him I'll make the final fitting adjustments. I still don't have the rear derailleur dialed in perfectly. I cant seem to get it just right in second gear. It clicks and jumps a little. First is better but not perfect. 3-8 work flawlessly.
I wonder if the rear derailleur's high limit screw is set correctly. I like to set the limit screws with the cable disconnected and shift the rear derailleur by hand while turning the cranks. I adjust the limit screws until the derailleur can shift to both the smallest and largest cogs cleanly with no rubbing or tendency to spill the chain in either direction. Then connect the cable and adjust the indexing.
I agree with FBinNY that the rear brake cable run is a bit too long but the saddle position and stem length will be better set when the actual rider is available for a fitting.
.....I cant seem to get it just right in second gear. It clicks and jumps a little. First is better but not perfect. 3-8 work flawlessly.
I assume that first is low, or the big sprocket. (I hate when folks number sprockets because I'm never sure which way they're counting)
Anyway now that I've unloaded the peeve of the day, you probably need to lower the derailleur via the B screw. High derailleurs cause problems on larger sprockets because the pulley is riding the sprocket through the chain, or nearly so.
Shift to the problem sprocket and look at the juncture of upper pulley, chain and sprocket. There needs to be daylight between them and roughly 1 inch of free chain running from the pulley to the sprocket. You can manually push the RD down a bit to see if things improve, and if so make it permanent by tightening the B screw.
With deference to HillRider, I doubt the limit screw is a factor, since the problem manifests on the 2nd sprocket where limits have no effect.
pat5319
12-04-11, 02:04 PM
Looks great...
1. Slide saddle back 1cm so that it is centered on post.
2. Swap to a 1cm shorter length stem.
You have just a tad of tilt-back of the saddle which is great - means you are not forcing your body to rely on the hands for support. (That leads to hand and wrist pain...)
Other than FBinNY's housing suggestion - looks good overall.
=8-)
One shouldn't suggest changing saddle/stem adj without knowing rider's dimentions such as thigh length etc
One shouldn't suggest changing saddle/stem adj without knowing rider's dimentions such as thigh length etc
True, final adjustments are always to the rider, but for presentation things should be set at the neutral starting position, ie. saddle level, to slight uptilt and centered in the post cradle. Also the post should be raised to what would normally be the right height if the frame was the right size. It makes the bike look more "right".
At this point it's moot, and can wait on fitting, but I'd attend to the brake loop, and dial in the derailleur adjustment, since neither is rider determined.
HillRider
12-04-11, 02:16 PM
With deference to HillRider, I doubt the limit screw is a factor, since the problem manifests on the 2nd sprocket where limits have no effect.
My thinking was (and I agree, which cog is #1 and which cog is #8 was not clear) is that the shift from the smallest to the second smallest cog is a problem. I've seen that happen when the high limit screw was too tight or too loose and the "spacing" between the cogs is then off. The same problem can occur between the largest and next largest cog if the limit screws are off. That's why I prefer to set them with the cable disconnected.
.... I prefer to set them [limit screws] with the cable disconnected.
There we agree. I always set limits independent of the lever, to avoid the index position masking the limit stop. I do it either before stringing the cable, of by shifting by pulling on the bare wire at the downtube (what I call the bowstring method).
I often see chains or derailleurs overshift into the spokes because the low limit was adjusted while shifting via the lever. The RD takes the low gear position based on the index notch, and no one notices that it isn't up to the limit, and one day it overshifts (oops).
mrrabbit
12-04-11, 05:50 PM
True, final adjustments are always to the rider, but for presentation things should be set at the neutral starting position, ie. saddle level, to slight uptilt and centered in the post cradle. Also the post should be raised to what would normally be the right height if the frame was the right size. It makes the bike look more "right".
At this point it's moot, and can wait on fitting, but I'd attend to the brake loop, and dial in the derailleur adjustment, since neither is rider determined.
Thank you FBinNY....
You and I both know the saddle should start approx. neutral...and close to proper height - with most dimensional changes being up front in the stem height, length and angle, and bar and lever and drop reach - and it is there that it gets pretty individualistic.
Of course, anyone reading a frame building and frame/bike fitting reference would discover this pretty quick.
=8-)
Powered by vBulletin® Version 4.1.12 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.