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New drivetrain for a commuter restore.

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New drivetrain for a commuter restore.

Old 08-02-14, 01:47 PM
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jawknee530
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New drivetrain for a commuter restore.

I recently purchased a 1991 Schwinn Crisscross for 7 day a week, year round commuting to school/work/etc as well as some light touring in the nearby hills. My two brothers are into mountain biking and I'm thinking I might keep two wheel sets so I can throw some mountain tires on it and do some light trail riding. I'm pretty tall (6'4") and was amazed to find a bike large enough for me and for just $20 on Craigslist. Fixing up the bike is also going to serve as a fun learning experience and hobby which I'm looking forward to as much as riding the thing. I'm really new to working on bikes and figuring out parts so I'm reaching out for help/advice.

The bike currently has the Suntour XCT derailleurs, X-press shifters, and the 3 x 7 gear set up that came with it back in '91. The drive train is super worn. Lots of chipped teeth and poor shifting on both ends. Also there's a bit of chatter in the BB so I'm thinking I need to get that replaced.

I like having the flat bars on it but am planning to get a new stem that's a bit further back and higher than what it has on it now for a bit more relaxed ride position and I've got that figured out but when it comes to the drive train and shifters I'm pretty lost. I've been doing some reading around the net and am thinking that a 46/32 crankset and a 12-25 10 speed cassette seemed like it would give me the gearing that I would want but when it comes to finding/choosing a proper BB/crankset/shifters/cassette/derailleurs I'm pretty darn lost.

I saw that SRAM sells a 2 x 10 flat bar pair of shifters so I figured I'd go that route. If I do that I have to get SRAM derailluers right? Should I go with mtn or road ones and whats the difference? Also is there different ways to mount them? What kind/size of BB do I need or how can I figure that out? I'm worried that the BB shell will limit what BB I can use which may limit my crankset options. Then I don't know if I'll need a new rear wheel in order to accommodate the 10 speed cassette. I'll need a new freewheel/freehub right?

Like I said I'm pretty lost but I'm also really looking forward to all the learning and the challenge. Been reading a lot but am to the point where I need to reach out for help. Thanks ahead of time for any help you can provide.

Here's a few pics I snapped.
imgur: the simple image sharer
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Old 08-02-14, 03:20 PM
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Regarding SRAM derailleurs, I believe most of SRAM's MTB groupsets now use rear derailleurs that only work with SRAM shifters, which pull about twice as much cable per "click" of the shifter than most shifters. I don't know what their current road bike shifter/derailleur combinations are like, but I suspect they may use the same system. As such, you'll need a SRAM rear derailleur, although a Shimano cassette will work as far as I'm aware.

There are (or were) some SRAM flat-bar shifters that were compatible with Shimano derailleurs, but I very much doubt those are available in 10-speed.

The BB shell won't limit your BB options, the standard for the dimensions and threading has remained the same for several decades, although if you get an external-bearing BB you may need to get the BB shell faced to make the faces parallel.

Under most circumstances I'd simply advise you replace the cassette/freewheel, the chain and maybe the chainrings if the wear was really bad, as a stopgap solution, but the Suntour sprocket clusters used different sprocket spacing to the Shimano/SRAM ones and are now very rare, so any replacement of drivetrain parts will mean new shifters and derailleurs too.
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Old 08-02-14, 03:52 PM
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Thanks for the reply/info. So I'm thinking that step one would be to get a freewheel/casette, shifters, rear derailleur, and chain. After I do that I can sort out the BB, crankset, chainrings, and front derailleur. Is there anything I need to look out for or know when choosing the derailleur or will just any fit on my bike/frame? Do I have to take into account anything about my rear wheel when choosing the freewheel/cassette?
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Old 08-02-14, 04:05 PM
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Originally Posted by jawknee530 View Post
Do I have to take into account anything about my rear wheel when choosing the freewheel/cassette?
Unfortunately, yes. If it's a thread-on freewheel, you'll be limited to a maximum of 7 speeds on the rear, and if you're a heavy rider you may have issues with axles bending or breaking due to the locations of the hub bearings on a freewheel hub. If it's a cassette (i.e. a set of sprockets held onto a splined body on the hub by means of a lockring), you'll need a whole new back wheel, as Suntour hub bodies aren't compatible with Shimano or SRAM cassettes. I apologise for not mentioning that initially, it somehow slipped my mind to point it out. The upshot is that you may well need a new rear wheel even to stick with 7-speed and you'll definitely need one to get more gears than that.

One piece of good news - any rear derailler from anything other than an entry-level groupset should bolt straight onto the hanger on your frame.

This may well prove more of a labour of love than a cost-effective way to upgrade the bike, but I'm not one to discourage that, most of my bikes are the result of something similar.
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Old 08-02-14, 04:13 PM
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Originally Posted by jawknee530 View Post
If I do that I have to get SRAM derailluers right?
The only Shimano compatible trigger shifters SRAM makes are Rocket(don't know if those are still available),Attack,and TRX. Pretty sure they only go up to 9spd.

Originally Posted by jawknee530 View Post
Then I don't know if I'll need a new rear wheel in order to accommodate the 10 speed cassette. I'll need a new freewheel/freehub right?
You'll def need a new hub for the 10spd cassette. However,you may also need to modify your frame. Current road hubs are 130mm and MTB are 135. There's a good chance your frame's rear spacing is narrower than that. Pull the rear wheel and measure before ordering parts.
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Old 08-02-14, 04:30 PM
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I picked up a '92 Crisscross a couple months ago to use as a commuter/gravel grinder/rain bike. The Crisscross is an unusual bike. Schwinn basically built a HT MTB frame using road bike tubing. It's lighter than MTBs of similar vintage, but it also has a good bit of flex. Over certain rough sections of asphalt I get some pretty significant bouncing/vibration. It happens with tires from 28c to 37c at varying pressures, so it's definitely the frame. I mention this because, though they're good as cheap utility bikes, I certainly wouldn't put very much money into one. Better to fix it up cheap and save your pennies for something better down road.

A 10-speed conversion will need shifters, both derailleurs, a cassette, a new or rebuilt wheel with a 10-speed compatible hub, and possibly a new crankset. Even with entry level groups, you're looking at several hundred dollars. If you're going to spend that kind of dough, I'd invest in a better frameset. That doesn't mean you can't make something really decent out of what you have. Here's my advice:

1. Your BB is loose-ball type so it's completely serviceable. Open it up, clean it out, put in fresh grease, put it back together (with new balls if necessary). Only if the axle or bearing cups show significant wear should you replace it.
2. Unless your cranks have stripped pedal threads, just replace any worn chainrings. Keep the crankset and you can probably keep the FD.
3. NOS Suntour freewheels can still be found, but they're pricey. Replace the worn freewheel with a new 7-speed Shimano HG. This will mean ditching the Suntour shifters.
4. If you want indexed shifting, get a Shimano Alivio M410 RD (about $25) and a set of TX30 shifters ($20). The left TX30 is "friction" so it will work with the existing Suntour FD.
5. If you don't care about indexed shifting, get a set of cheap friction thumb shifters and keep both existing derailleurs. The Suntour RD will friction shift just fine on a Shimano HG freewheel. This is what I did on mine.

To answer some of your specific questions ...

Flat bars have a different diameter than road bars. In general, flat bars require MTB/Hybrid style thumb or grip shifters.

Getting a 10 speed compatible rear wheel means changing out the entire hub. You'll need new spokes too to match the new hub size and increased dish. The stock rims are alloy single wall - ok, but nothing special - so you're probably better off just buying a whole new wheel if you're not satisfied sticking with 7-speed. The Crisscross does have at least 130mm spacing which will work with 10-speed road hubs.

The BB shell is standard 68mm English, so replacement options are plentiful. If you don't go with a square-taper crank, your choice of crank will determine the BB you need. If you go this route, make a lot of measurements and do a lot of research. Nothing worse then bolting in a new crankset only to discover the rings won't clear the chainstay.

For the kind of riding you want to do, there's just no need to upgrade to a state-of-the-art drivetrain. I did a 50 mile, 17 MPH road ride on mine today with a friction shifted mostly stock 3x7 drivetrain and at no point did I find myself needing something better.
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Old 08-02-14, 04:39 PM
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Originally Posted by Kopsis View Post
3. NOS Suntour freewheels can still be found, but they're pricey. Replace the worn freewheel with a new 7-speed Shimano HG. This will mean ditching the Suntour shifters.
Not so! SunTour and Shimano spacing was the same for 7-speed. As long as the OP keeps the SunTour shifters and derailleurs, a 7-speed Shimano freewheel should index just fine. (It may need a little adjustment, but from the OP's description, it does anyway.)

My vote would be for just replacing the worn freewheel and chainrings, since that would be the simplest and cheapest option. I agree that replacing a whole bunch of parts to get 2x10 won't vastly improve things -- when wide range and low gears are desired, triples really shine.
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Old 08-02-14, 04:57 PM
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You guys are awesome. So I think I'll go with a new shimano 7 speed freewheeling and cassette. The bike has a terrible time shifting right now though. How do I know if the problem is the shifters or the deraileurs? And what's the difference between indexed and friction shifting?
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Old 08-02-14, 05:04 PM
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Originally Posted by jawknee530 View Post
You guys are awesome. So I think I'll go with a new shimano 7 speed freewheeling and cassette. The bike has a terrible time shifting right now though. How do I know if the problem is the shifters or the deraileurs? And what's the difference between indexed and friction shifting?
With indexed shifting, you "click" from one gear to the next, with friction shifting, there's no click -- you can push the shifter each way and have to locate the gear yourself. It's not hard, but indexed shifting is more convenient.

What you describe sounds to me like a system that just needs adjusting -- bikes do from time to time.
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Old 08-02-14, 05:44 PM
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Originally Posted by jawknee530 View Post
. . . The drive train is super worn. Lots of chipped teeth and poor shifting on both ends. Also there's a bit of chatter in the BB so I'm thinking I need to get that replaced. . .
Here's a weird, crazy idea:
Why not clean, inspect, lube, adjust the shifters, cables, derailleurs, bearings, etc that you have and get the shifting working well. Then ride it so you'll know what ratios you really want.

It does not look too worn and likely does not have chipped teeth. It will probably work better than some mis-matched new parts ever will and you'll have to learn how to do all that stuff anyway.
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Old 08-02-14, 05:50 PM
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The 14 and 16 gears are chipped badly and actually missing a few teeth. Also the photos posted are a few weeks old. It has since been cleaned and adjusted. It helped but it's still spotty as he'll when trying to shift.

Last edited by jawknee530; 08-02-14 at 05:58 PM.
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Old 08-02-14, 06:12 PM
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After taking a closer look at picture #2 , it appears you already have a Shimano freewheel installed (it has HyperGlide shifting gates on it.)

The chainring teeth don't look too bad yet. You probably just need a new freewheel and chain, and a good adjustment.
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Old 08-02-14, 06:17 PM
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So the current rd is not indexed? And why the x30 instead of say the m310 shifters?
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Old 08-03-14, 01:39 AM
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Originally Posted by Airburst View Post
Unfortunately, yes. If it's a thread-on freewheel, you'll be limited to a maximum of 7 speeds on the rear,
Actually, no. "Thanks" to the popularity of rear hub electric motors( I believe) there are both 8 and 9-speed freewheels available.
Originally Posted by Airburst View Post
....and if you're a heavy rider you may have issues with axles bending or breaking due to the locations of the hub bearings on a freewheel hub.
Yeah, THAT issue remains, and is in fact even worse.
And they come with MTB-style ratios, which isn't to everybodys liking.
This isn't a recommendation, just a mention of what's possible.
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Old 08-03-14, 03:20 AM
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Originally Posted by dabac View Post
Actually, no. "Thanks" to the popularity of rear hub electric motors( I believe) there are both 8 and 9-speed freewheels available.
I just looked it up... I'd heard of 8-speed ones, but I thought they died out when cassettes went big. Given that the OP is 6'4" and planning to potentially use the bike offroad, I'd be concerned with the reliability of a 7-speed freewheel system, let alone one with an even wider freewheel....


As for the SunTour vs Shimano compatibility, I wasn't aware the sprocket spacing was the same, I had issues getting the shifting to work while trying to retrofit a 7-speed Shimano freehub wheel onto a bike with a SunTour derailleur and shifter which eventually forced me to replace the whole lot with Shimano, but that might have been that specific derailleur being damaged or worn.

OP, derailleur's aren't indexed, the shifter is indexed and the derailleur is designed to move the right distance with each click of the shifter to move the chain between one sprocket each time. Although the distance between each sprocket is the same for Shimano and SunTour 7-speed systems, the amount of cable pulled by the shifter with each click is different between the two manufacturers, and as such they only operate with derailleurs designed to work with them.
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Old 08-03-14, 04:02 AM
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Originally Posted by ThermionicScott View Post
After taking a closer look at picture #2 , it appears you already have a Shimano freewheel installed (it has HyperGlide shifting gates on it.)

The chainring teeth don't look too bad yet. You probably just need a new freewheel and chain, and a good adjustment.
Good eye! That does, indeed, appear to be a HG freewheel -- In which case chipped/missing teeth is actually a design feature to help shifting.

A closer look at picture 3 shows daylight between the chain and the chainring. This is indicative of a chain that has "stretched" well past the limit and is now riding up on the teeth. That will also lead to poor shifting and possibly slipping under power. A new chain is probably a good first step.
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Old 08-03-14, 04:08 AM
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Originally Posted by jawknee530 View Post
So the current rd is not indexed? And why the x30 instead of say the m310 shifters?
I suggested the X30 because the front shifter is non-indexed so it will work with the existing Suntour FD despite any cable pull differences.

However, derailleurs rarely wear out. So if your existing Suntour shifters are functional and there's no apparent damage to the derailleurs, a new chain and proper tuning may let you keep everything stock.
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Old 08-03-14, 06:48 AM
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I spent close to $500 to upgrade my 1990 Trek 7000. This included new wheels with a Dynamo Front 3N72, LX 10sp rear T670, Mavic XM317 rims,and WS db spokes. The drivetrain was Deore 3x10 shifters, an XT M786 rear derailleur, a KMC chain and a 11/34 10sp Shimano cassette. I also put XT V-brakes and Deore levers on it. And the dynamo light added another $110 to the total.

Was it worth it to put all this on an old bike? Yes and no. It rides like it is brand new, with all the latest components, but at the same time the bike is almost obsolete. This is a 26" bike, when almost everything these days is 29er or now 27.5. It also doesn't take disc brakes. For the $500 or so I spent (and this was with looking for bargains everywhere) I'd have maybe a low end hybrid like a Sirrus, but I have a sorta/kinda higher end frankenbike.

But I guess the ultimate answer is yes, because I ride this bike all the time now. I even ride this sometimes instead of getting on my carbon road bike when I have the choice. It really does ride nice with silent perfect shifting that just requires a flick of the lever instead of a push, brakes that stop on a dime with a light touch, and a light that just lights the road, not the trees around you and is always ready.
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Old 08-05-14, 12:28 PM
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I brought my bike in to a local shop to have the wheels trued and was told they had sat outside for too long and the spokes are rusted into place so they can't be trued. I have 700 x 35 tires on the bike right now and want to get a cheap pair of wheels to replace my current ones. Does anyone have any recommendations for a cheap set online that'd work with my current set up?
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Old 08-05-14, 12:42 PM
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Originally Posted by jawknee530 View Post
I brought my bike in to a local shop to have the wheels trued and was told they had sat outside for too long and the spokes are rusted into place so they can't be trued. I have 700 x 35 tires on the bike right now and want to get a cheap pair of wheels to replace my current ones. Does anyone have any recommendations for a cheap set online that'd work with my current set up?
That sucks! One would think they'd know to lube the nipple holes and loosen first on old wheels. Nipples should be brass, so while they might be firmly in place, they can't rust to the spokes.
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Old 08-05-14, 12:47 PM
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Originally Posted by ThermionicScott View Post
That sucks! One would think they'd know to lube the nipple holes and loosen first on old wheels. Nipples should be brass, so while they might be firmly in place, they can't rust to the spokes.
It's possible that he was just BSing me and I didn't/don't know enough to realize it. I asked about getting new wheels and he said they only had $100+ wheel sets there and I was better off getting a cheap set online. Only after I got home I realized i didn't know enough to pick out a wheel set. For instance how much does the rim width matter? I know I'll need one with a rear hub that attaches to a freewheel not the freehub type but I don't know if there's different sizes or types of the rear hub I have to look out for. Also I don't know how the depth of the wheel affects it. I'll be doing some reading (yay learning!) but I figured I'd ask here to cover my bases.
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