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Drive Train Advice Please

armoureddrummerarmoureddrummer Posts: 145
edited April 2011 in The workshop
Hey fellow commuters,

I am faced with a dilemma. I am fairly new to the bike tinkering addiction. 2 years mountain biking on a stock bike and now commuting on 2 wheels but just getting the bug.

My project is a Trek 7300 hybrid. I am trying to lighten it a bit at a time.

So far I have installed a set of lightweight bullhorn bars, LX V-brake levers, carbon spacers and titanium stem (needed to drop from a 100 - and 80mm to accommodate reach on bars so why not?).

I am now looking to lighten wheels and drivetrain.

I anyone has 700c wheels which are nice and light that will take tyres in the 700x38 ish size, let me know.

Anyhoo - Drivetrain:

Current drivetrain is Shimano Alivio so anything is probably an improvement.

I am going to buy parts a bit at a time over the next while so I need some direction. SRAM Powerglide II PG970 cassettes on CRC are currently reduced heavily which has caught my eye. From research, it appears that I can pretty well use SRAM accross the board but cable pull is an issue if shifters and der's don't match.

For info, I am using old retro shimano sis friction shifters to allow me to get them into the position I want them on my bullhorns.

Here are my questions:
1 - Can Shimano Der's be used with SRAM cassettes/Chainsets?
2 - Can I change cassette and chain to SRAM and continue using Shimano Chainset?
2.5 - Cranksets seem to be available from a lot of different manufacturers - if they suit 9 speed are they all compatible?
3 - Will the lack of indexing in my friction shifters allow enough movement within their limits to get the full range required for SRAM Der's?
4 - If anyone is familiar with component weights between shimano and SRAM, can you please advise which SRAM component ranges are lighter and in what order?

My plan:

1 - Cassette, Freehub body, chain
2 - Crankset & BB
3 - Wheels
4 - Der's
5 - Suspension forks (current ones are cheapy but not much option about for 700c sus forks - hoping more range will appear over the next while).

Does this seem sensible?

Long story but hopefully easy answers?


  • cooldadcooldad Posts: 32,904
    Yes, no maybe. Depends on your bb and chainline.
    Wow! Probably but why not go the whole hog and join the 21st century.
    Higher numbers tend to be lighter, with XO and XX lightest.
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  • Thanks Cooldad,

    What do you mean by chainline? This one is new to me?

    [email protected] shifters. I did have the alivio indexed shifters on my original bars but as with most of them these days, they are joined to the brakes. My brakes are mounted at the end of my bullhorn bars (like a TT set up) which leaves me with a tricky gearing situation. I must admit, the friction shifters actually work better than the rubbish alivio set up! I have toyed with bar end shifters but not really in my preferred position! Quite retro but enjoying it at the moment. I have an X9 drive train on my trail bike so I do come forward in time every weekend!
  • MoodymanMoodyman Posts: 158
    How fit are you and what level do you ride at?

    I've never understood the pursuit of weigh loss on a commuter bike - especially one as mid-range bike as the Trek 7300

    You've got to spend serious money to save a few hundred grammes and lose it all a soon as you add a mudguard or lights in winter.

    If you're riding it as stock - that is knobbly tyres, the best upgrade you can make is put on slicks for the road.

    Other than that, leave it as it is and replace parts as they wear out.
  • The RookieThe Rookie Posts: 27,748
    I disagree, on a mid range bike weight loss is much cheaper than on a high end, I've shed over 1Kg on mine since I first built it (so about 10%) for only about £80 - its all about making the right choices!

    When I replace my tyres I'll be saving about 320g for only £45ish.

  • It is not as important as shedding weight on my Mountain bike but as I pull a lot of weight in panniers, lights etc and live on a 4th floor flat ..... anything helps my back!

    I am taking the budget route as well. So far second hand bits are coming in as I can afford them. Just picked up a set of old type hollowtech cranks for about a tenner etc. The bike cost me £140 - if I can get it running well and fairly light having spent less the £250 all in I'll be happy.

    Riding semi slicks (700c) and am also pretty fit. Riding 3 days a week, 5 miles each way at 15mph avg via 2 large hills with heavy bike and 2xheavy panniers. Then out on the full susser for trails action at the weekend (Round the Red then half the blue at Glentress usually). Not so much of an issue peddling the bike, more the lifting.

    Just think that as I am going to ride this bike for a while as my commuter, I might as well be happy it is as good as I can afford too.

    One more question for you guys if you could help. The cranks I have bought are Octalink and will need a new BB. I have a 68mm casing but been trying to work out the spline length.
    Overall crank to crank external is 150mm, measurement from the end of the taper square spine to the face of the crank is 12mm on the size i exposed, so I assume 150mm minus 24mm =126. A lot of research says 68x113 is the most common size. Is it worth me removing the cranks to check or do you think I am safe with the crude measurement method? I am guessing this needs to stay the same to make sure the chain runs in line with original design?
  • The RookieThe Rookie Posts: 27,748
    Remove the cranks and measure the BB axle length, if you go Shimano to shimano I believe you need the same axle length as they use the same offset to chainline.

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