Couple questions
10-15-20, 05:32 PM
#1
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Couple questions
I have a 2018 Specialized Tarmac Sport. I have some maintenance questions I’ve been longing to ask so here they are:
1. When I first bought the bike I installed some plastic bottle cages. Unfortunately I was a tool and stripped one of the bolts while screwing them in so the bottle cage is not removable. It doesn’t make any sounds or cause any problems and the bottle cage is perfectly fine, but in the future I may want to change them for lighter ones or remove them completely. How would I go about removing the stuck bolt? It just spins and doesn’t extract. Can I do it home simply or should I take it to a mechanic?
2. The bike has a Praxis Alba chain set which has proprietary measurements and a threaded praxis BB (I think M30). It’s a BSA thread. If I wanted to upgrade my cranks to a Shimano Ultegra R8000 one, do I have to change the BB? If so, should a 68mm BSA R8000 bottom bracket work?
3. I replaced the brake cables twice now and the rear brake cable is rubbing against the plastic insert where the cable comes out from the frame. I think it’s resolvable with a sheath cap in the insert, am I thinking right?
4. The Alba chainset that’s on my bike says tighten to 40NM. My torque wrench only goes up to 20. Should I take it to a mechanic to let them tighten it or can I just ride with 20NM?
5. I tighten my brakes (rim) to 7NM because the manufacturer doesn’t provide a recommended torque for brakes and 7NM is recommended for the seatpost clamp so it should be safe. Problem is that the brakes misalign every ride and I lose power because of brake rub. Should I tighten them to 8NM or more or will this damage the carbon?
6. When I take the top cap off the stem I see another bolt that I can tighten and also screw the top cap into. Next to the screw there is a printed message saying “recommended torque 7NM”. I tried tightening it to 7NM but it just keeps tightening with medium resistance. Eventually the bolt bottomed out and it’s just there now. I can undo it to where it was before and it’s not stuck. Did I break something? Why doesn’t it tighten to 7NM?
thanks guys
1. When I first bought the bike I installed some plastic bottle cages. Unfortunately I was a tool and stripped one of the bolts while screwing them in so the bottle cage is not removable. It doesn’t make any sounds or cause any problems and the bottle cage is perfectly fine, but in the future I may want to change them for lighter ones or remove them completely. How would I go about removing the stuck bolt? It just spins and doesn’t extract. Can I do it home simply or should I take it to a mechanic?
2. The bike has a Praxis Alba chain set which has proprietary measurements and a threaded praxis BB (I think M30). It’s a BSA thread. If I wanted to upgrade my cranks to a Shimano Ultegra R8000 one, do I have to change the BB? If so, should a 68mm BSA R8000 bottom bracket work?
3. I replaced the brake cables twice now and the rear brake cable is rubbing against the plastic insert where the cable comes out from the frame. I think it’s resolvable with a sheath cap in the insert, am I thinking right?
4. The Alba chainset that’s on my bike says tighten to 40NM. My torque wrench only goes up to 20. Should I take it to a mechanic to let them tighten it or can I just ride with 20NM?
5. I tighten my brakes (rim) to 7NM because the manufacturer doesn’t provide a recommended torque for brakes and 7NM is recommended for the seatpost clamp so it should be safe. Problem is that the brakes misalign every ride and I lose power because of brake rub. Should I tighten them to 8NM or more or will this damage the carbon?
6. When I take the top cap off the stem I see another bolt that I can tighten and also screw the top cap into. Next to the screw there is a printed message saying “recommended torque 7NM”. I tried tightening it to 7NM but it just keeps tightening with medium resistance. Eventually the bolt bottomed out and it’s just there now. I can undo it to where it was before and it’s not stuck. Did I break something? Why doesn’t it tighten to 7NM?
thanks guys
10-15-20, 07:25 PM
#2
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1- RivNut type threaded inserts are a really poor way to create a mounting boss in a thin wall tube, except for the other ways
As the insert is compressed during install it's threads can become deformed and if not followed up with a thread chasing can allow bolts to very easily be started improperly. If the insert in in a tube that has a large enough opening at either end (think of a seat tube) then the insert can be removed from the tube wall and also from the tube's interior. The insert's lip (on the outside surface of the tube) can be pried up so that the insert "falls" into the tube. If down carefully a fresh insert (of the correct spec) can be installed. I've done this quite a few times.
2- Sorry I don't have that memorized
3- Casing end caps with a snout do work well to reduce the inner cable's friction at the cap's end. Until the snout breaks off or wears through. Then simply install another.
4- I would not ride a bike with critical fittings only tightened to half the needed amount. Do the job right the first time even if you need a third party to help out.
5- Since I don't know what design, brand of brakes you have or how the wheel/dropout securement is done I have no base to advise you from. But we deal with this stuff weekly at work and generally can get longer lasting results then you are experiencing. One question I would ask is whether the wheel is moving within the frame/fork, whether the caliper is moving about on it's mount (assuming disks).
6- Without seeing the problem in person I can't say much. It sounds like the fork steerer has a compression plug in it and either the plug is spinning while you try to tighten it's draw up bolt. But the plug's expanding cone could be damaged, the bolt could be damaged of some other thing is going on that alludes my long distance assessment skills. Andy
As the insert is compressed during install it's threads can become deformed and if not followed up with a thread chasing can allow bolts to very easily be started improperly. If the insert in in a tube that has a large enough opening at either end (think of a seat tube) then the insert can be removed from the tube wall and also from the tube's interior. The insert's lip (on the outside surface of the tube) can be pried up so that the insert "falls" into the tube. If down carefully a fresh insert (of the correct spec) can be installed. I've done this quite a few times.2- Sorry I don't have that memorized
3- Casing end caps with a snout do work well to reduce the inner cable's friction at the cap's end. Until the snout breaks off or wears through. Then simply install another.
4- I would not ride a bike with critical fittings only tightened to half the needed amount. Do the job right the first time even if you need a third party to help out.
5- Since I don't know what design, brand of brakes you have or how the wheel/dropout securement is done I have no base to advise you from. But we deal with this stuff weekly at work and generally can get longer lasting results then you are experiencing. One question I would ask is whether the wheel is moving within the frame/fork, whether the caliper is moving about on it's mount (assuming disks).
6- Without seeing the problem in person I can't say much. It sounds like the fork steerer has a compression plug in it and either the plug is spinning while you try to tighten it's draw up bolt. But the plug's expanding cone could be damaged, the bolt could be damaged of some other thing is going on that alludes my long distance assessment skills. Andy
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10-16-20, 03:13 AM
#3
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Could you add some pictures of the brakes, and also the stem bolt?
trev
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10-16-20, 04:13 PM
#4
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#2 - you would need a new BB for a new drivetrain brand. Praxis is their own set up. Seriously if they are not worn out don't change them. Praxis stuff is pretty good.
#4 - everyone had their own opinion on torque, if you don't have a torque for the setting either buy one or find a source to use one. It not a number you have to be spot on but they give a number for a reason. If your off by less than 5% your fine, but over or under can be a problem maker IMO.
#4 - everyone had their own opinion on torque, if you don't have a torque for the setting either buy one or find a source to use one. It not a number you have to be spot on but they give a number for a reason. If your off by less than 5% your fine, but over or under can be a problem maker IMO.
