Hi, I am trying to rebuild a Specialized Stumpjumper Pro. It is just the frame. Do I need a specific bottom bracket, aligned to the crankset, front and rear derailleur? Maybe a stupid question but I haven’t a clue and keep buying stuff and nothing seems to work. My front derailleur wont reach the large ring, it skips off the rear cog as well. I want to know if I have a certain crankset do I need a certain rear cassette etc. I’m so confused. Thank you Also why are bottom brackets in different lengths?
Group set help
- Thread starter judgetedd
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jonthefish
Senior Retro Guru
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There's a lot to get your head round!
1. Bottom brackets length is usually matched to the cranks. Have a look here https://www.sheldonbrown.com/bbsize.html
2. Indexed mechs can be a pain. BUT - make sure you have the limit screws and cable tension set properly. Have a look here. https://www.parktool.com/blog/repair-he ... adjustment
Also here https://www.google.com/search?client=fi ... adjustment and here https://www.youtube.com/watch?v=ZNG7g83lI-s
Don't worry and don't be afraid to ask questions - I still do all the time. Plenty folk here will help.
And when it all gets too much polish something (hard to go wrong there) and have a beer!
1. Bottom brackets length is usually matched to the cranks. Have a look here https://www.sheldonbrown.com/bbsize.html
2. Indexed mechs can be a pain. BUT - make sure you have the limit screws and cable tension set properly. Have a look here. https://www.parktool.com/blog/repair-he ... adjustment
Also here https://www.google.com/search?client=fi ... adjustment and here https://www.youtube.com/watch?v=ZNG7g83lI-s
Don't worry and don't be afraid to ask questions - I still do all the time. Plenty folk here will help.
And when it all gets too much polish something (hard to go wrong there) and have a beer!
CassidyAce
Senior Retro Guru
Re:
The above is good advice. What year is the StumpJumper and which parts are you trying to attach to it?
The above is good advice. What year is the StumpJumper and which parts are you trying to attach to it?
As jonthefish said.
And, pictures/year would help.
Basically:
bottom bracket - has different length, type and diameter. What you probably need is a square taper (type), diameter should be fine (other type is rare) and length according to the crankset you are planning to use.
crankset - determines bb length, for 3x7 and 3x8 systems, they should be interchangeable.
front derailleur - what you need is correct cable pull (top/bottom) and diameter of the tube (actually seems you have both correct) to be able to mount it and connect with cables. Then if it doesn't reach, might be that the bb is incorrect (way too long) or the derailleur has the limit screw tightened so that it won't reach. Or, that it is some derailleur that won't reach anyway which would mean it is a road type (it probably isn't).
cassette - number of cogs should be same as shifters and rear derailleur need (and chain and rear hub should be also one made for the same), apart from that, most common you buy should be fine.
chain can be any, made for the number of cogs on the cassette. if it skips off, it should probably be about adjusting, as mentioned above.
Good luck!
And, pictures/year would help.
Basically:
bottom bracket - has different length, type and diameter. What you probably need is a square taper (type), diameter should be fine (other type is rare) and length according to the crankset you are planning to use.
crankset - determines bb length, for 3x7 and 3x8 systems, they should be interchangeable.
front derailleur - what you need is correct cable pull (top/bottom) and diameter of the tube (actually seems you have both correct) to be able to mount it and connect with cables. Then if it doesn't reach, might be that the bb is incorrect (way too long) or the derailleur has the limit screw tightened so that it won't reach. Or, that it is some derailleur that won't reach anyway which would mean it is a road type (it probably isn't).
cassette - number of cogs should be same as shifters and rear derailleur need (and chain and rear hub should be also one made for the same), apart from that, most common you buy should be fine.
chain can be any, made for the number of cogs on the cassette. if it skips off, it should probably be about adjusting, as mentioned above.
Good luck!
