Main­te­nance

Some fixes that will have a great bear­ing on your ride

Canadian Cycling Magazine - - CONTENTS - by Nick Di Cristo­faro

Bot­tom bracket work that you can do

The bot­tom bracket is where your en­gine, legs that is, con­nects and trans­mits force to pro­pel your bike for­ward. Ev­ery bi­cy­cle has a BB. The part of­ten seems sur­rounded i n con­fu­sion be­cause of dif­fer­ent types (and the litany of noises and creaks that come from them). There are two ba­sic types of BB on mod­ern bi­cy­cles: threaded and press-fit. A threaded bot­tom bracket is the older sys­tem (and more re­li­able, in my opin­ion) with bear­ings con­tained in­side threaded cups that are screwed into the frame. The bear­ings them­selves sit out­side of the frame. A press-fit bot­tom bracket’s bear­ings are fit­ted into a frame ei­ther di­rectly or into cups that are pressed into the frame. Here are some tips and ba­sic main­te­nance you can do at home to pre­vent costly fail­ures down the road.

I rec­om­mend a full over­haul of the BB at least once or twice a year on your road bike and more of­ten on a moun­tain, gravel or cy­clocross bike, de­pend­ing on the conditions you ride in. If you have rid­den in a ma­jor down­pour, then it’s a good idea to, at the very least, re­move your crank, in­spect the bear­ings, and clean and grease the seals.

The ba­sic clean

Make sure you are fa­mil­iar with the re­moval process of your par­tic­u­lar brand of crank. Once re­moved, clean the shaft and chain­rings with de­greaser and in­spect the chain­rings. Now would be a good time to re­place them if they are worn. Re­move bear­ing seals if it’s pos­si­ble. Ro­tate the inner race of the bear­ing on each side with your hand. If the bear­ings feel gritty or are hard to turn, then the bear­ings, and pos­si­bly the cups, too, will have to be re­moved for fur­ther ser­vic­ing. If the bear­ings feel fine, then in­spect the in­side of the BB shell and clean out any mois­ture, dirt and old grease. Apply grease to the out­side of the bear­ings and a light amount on the crank shaft it­self be­fore re­in­stal­la­tion. Make sure to re­in­stall any ap­pro­pri­ate wash­ers and spac­ers in the or­der they were re­moved. Tighten any bolts to spec. Give the crank a spin by hand with­out the chain on the rings to check for smooth­ness. One fi­nal step is to check for play by grab­bing the crank arms and rock­ing them back and forth.

Work­ing on the bear­ings

If, dur­ing the ba­sic clean­ing, you no­ticed the bear­ings are in need of ser­vic­ing or re­place­ment, then you’ll have to re­move them. If you don’t have the tools you need, take your bike to a good shop.

A threaded BB’S cups are usu­ally re­moved and re­placed as a unit. Some brands have ser­vice­able bear­ings. Make sure you do your re­search on your model. If you have a press-fit BB, you’ll have to take the bear­ings out of the frame. There are spe­cial tools avail­able for spe­cific types, such as one-piece press-fit BBS and two­piece BBS that are threaded to each other. Make sure you know what BB you have be­fore you start the process.

If your bike has a press-fit BB with two sep­a­rate pieces, you can use a large-face alu­minum (or other soft metal) drift punch to knock out the bear­ings/cups. You must take care to en­sure that you strike the in­side of the bear­ing/cup and not the frame it­self, which will get gouged. Work around the perime­ter of each bear­ing/ cup to knock out the as­sem­bly evenly. As you hit it with the punch, you should start to feel move­ment as the as­sem­bly moves out­ward. Af­ter you’ve re­moved the bear­ings, clean the BB shell. Be­fore you in­stall new bear­ing/cups, grease the outer race of each. If the re­moval process was su­per easy, I rec­om­mend us­ing a bear­ingre­tain­ing com­pound in­stead of grease, which pro­vides ex­tra hold­ing strength. The com­pound might help to pre­vent fu­ture noises and creaks.

Fi­nally, in­stall the bear­ings us­ing an ap­pro­pri­ate bear­ing press. This press adds an even amount of force to the out­side race of the bear­ings. Note: never press on the in­side race of any bear­ing dur­ing in­stal­la­tion as it will ruin, or even pos­si­bly break, the inner race loose from the outer race. Once you have your new BB in place, you can re­in­stall your crank and get ped­alling.

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