Replacing components on a mountain bike

Factual Questions
1

I have a very old mountain bike, a Ross Mt. Hood which I really love. (nearly identical photos and specs listed on this site)… however, the gear shifts are really outdated and I would love to upgrade to “click-shift” components.

I picked up another bike, a GT Backwoods for very cheap (details and specs on this site)… it has what I want, but is not as comfortable as my Mt. Hood, and just does not “feel right”… since I got it for cheap, I thought:

My best outcome would be to switch the brakes, shift levers, and derailleurs from the Backwoods to the Mt. Hood.

The brakes appear to be screwed in via standard moorings, but I am not sure about the Derailleurs and crankset… it looks like the Mt. Hood has SunTour and the Backwoods Shimano… are these standardized in their mounts? any Doper bike experts have advice for this handy bike noobie?

2

The derailleurs are designed to cover the range of the gears they are matched to. A mountain bike will have a much wider gear ratio which means 1st gear is a much larger gear than a touring set. The derailleur has to be able to handle the slack between the tallest gear and the shortests gear. Mountain bike derailleurs will have a longer idler arm to handle this. If both bikes are mountain bikes than the idler gears mechanism should be about the same size. If 1’st gears are the same size I’d say you’re good to go.

If your good bike is really old it might have an eliptical gear set in front. That means the gears are not round and this is obvious when you spin the crank. It was a system used briefely for racing but died quickly because it was linked to knee injuries. I doubt you would see it on a mountain bike.

The only other thing I can think to check is the spacing between the gears. the shifters are going to be matched to derailluer and the spacing between the gears.

Before I do any of this I would go to a bike shop and explain what you’re doing to get some options. You may be able to trade your new bike for a retofit of the old one.

3

I really want your old shifters and derailleurs! Your XC Sport derailleurs pull differently from the Shimano so they will have to go at the same time. They won’t be elliptical, the XC gruppo were round.

4

You can’t swap the brakes because they are different but I don’t see why you can’t swap the brake levers. All they do is pull a wire.

5

MikeG:
The problem with the old shifters and derailleurs is that you have to push the shifter far enough to shift gears, and this involves over-shooting the gear… once you are “in gear” you need to manually move the shifter back a bit to stop the clicking noise of having the derailleur slightly past the gear. It takes too much effort and attention, whereas the click-shifters are simple and easy…

I have had the bike “tuned up” in the past, and this has always been “the way that it is…”

Have I been led astray, and this can be “tuned” to work better? Btw, if I am able to work all this out, I will PM you about the components.

6

Those are some of the best shifters made in the last 25 years imho. They need to be properly set up and they will not Click into position like the new indexed shifters so they have fallen out of favor.

If you really don’t want them, please let me know as I am working on restoring a 1987 mtn bike and could use pretty much all the Suntour stuff off your Mt. Hood.

I had a Mt. Hood when I was 16 years old.

7

The Ross has 6 gears in back and the GT has 8 gears so I doubt switching out the shifters will be…fun. I have a Fisher (same bike as in pic and very comfortable and I am incapable of parting with it) that’s around the same vintage as the Ross and it has index shifting, so you may be able to find 6 speed indexed shifters if you look hard enough (I can’t remember if the Fisher is 6 or 7 and no you can’t have my shifters :D). IIRC the front derailleur on the Fisher is not indexed. That might be a lost cause. Also, rim brakes today require a much lighter touch and levers are much smaller than the motorcycle style brake levers of yore so you might want to use caution if you’re going to replace your brake levers.

8

Shimano made “biopace” mountain bike cranksets with elliptical chainrings back in the late 80’s and maybe early 90’s. I have a 1988 Specialized Rock Hopper that came with those (they’ve long since been replaced) in a 28-38-48 configuration. They really don’t make much difference in the shifting, though – you just have to mount the front derailleur up a little higher to provide clearance from the wonky chainring.

Anyway, all this is to say that even if one bike had elliptical chainrings and the other didn’t, I don’t think it would make any difference as far as swappability goes.

9

If the brakes are mounted to the fork in the same place, with the same separation, does it matter if one is “side-pull” and the other “center pull”?

10

Not as far as levers go - the big difference here is when you go to V-brakes, which require an entirely different lever setup. Mixing and matching with V-brakes isn’t generally recommended (it is only possible by installing special tensioners in the brake cable run, and usually isn’t worth it.)

11

Maybe instead of trying to swap components from the new bike to the old, figure out what is ‘wrong’ with the new bike and fix that. Is the frame size bigger or smaller than the Ross? What about the distance from saddle tip to handlebar, and the height/angle of the stem? If the frame size is right you should be able to duplicate the riding position by changing a few relatively inexpensive things like the stem, bar, and seat post. If the frame size is wrong I’d suggest selling the new bike and starting over.

One thing about ride comfort - your old frame is steel right? Virtually all new cheap to mid-range bikes will have aluminum frames. These are lighter and stiffer than steel but result in a harsher ride.

12

I used to work in bike shop back in the day and must have built a couple hundred of the Mt. Hoods. Great bike for the price and built like a tank.

The primary problem with swapping out just the deraileur and shifter is that the entire drive train (shifters, deraileur, chain and cogset) is meant to work together- especially with index or “click” shifting. Older cogsets were not as precisely or equally spaced beacuse there was no need for this detail with the older “friction” shifting.

It may work for you, or you may find it impossible to adjust the system so that it works smoothly in all gears. You will probably find that you can get the chain to run smooth in some of the gears, but others will be “jumpy”, noisy and misalingned. You could also replace the cogset and chain, but there you could run into issues with the cogset not fitting onto or not being compatible with the old wheel and hub.

As far as the brakes go, it won’t work to swap them out as the mounting points are different on the two bikes (the Mt Hood axis of swivel is higher on the fork than the GT). Also, while not a show stopper, the difference between center pull and side pull means you’d have to change the cable routing and perhaps need to kludge together a cable stop point - although it appears that GT has the cable stop built into the brake unit, whereas tha Mt Hood had a cable stop hanger as part of the headset stack- so taking brakes from the GT and mounting them on the Hood should be easier than doing it the other way aaround - if that makes sense).

Good luck.

MikeG- I’ll have to check through my bag of leftover parts, but I may have some Suntour XC stuff for you. 20 years ago I swapped out all the XC parts from a Cannondale and replaced them with DeoreXT. I think I still have have the Suntour stuff floating around somewhere. If I find them I’ll let you know. Uhhh- why no, I’m not a packrat…

13

Pipper: given your experience, do you have any recommendations for how I should proceed? Are there compatible components for this bike? Can I swap out the entire crank/deraileur/shifter combination?

14

The problem is that you are trying to change out parts that are essentially antiques.

However, never under-estimate the ability of your local bike shop to keep, what should be by all rights, essentially worthless garbage sitting around waiting for the day that someone like you needs those parts. I was amazed when one of the older mechanics at my shop whipped out an early 1960’s era Campaganolo bottom bracket that was just what was need for a customers problem.

Your best bet if you are committed to keeping this bike would be to replace the entire drivetrain with a matched set of index shifting components.

That said, you may not need to touch the front deraileur and/or the crankset. Index shifting for the front deraileur is overrated (I mean, come on, there are only 2, maybe three chainrings, you can probably live with standard shifting). You also won’t need to change out the cranks as long as the new chain seats properly on the chainrings (index shifting chains generally altered the WIDTH of the chain, but the length between links is typically the same, and because the front chainring is less sensitive to width differences than the cogset, you may be ok there).

Assuming you can ignore the crankset and front deraileur, you will need a rear deraileur, a matched rear shifter, new chain, and a new cogset (make sure its a cogset that is compatible with your hub, I don’t think the hoods ever had cassette type cogset). A sticky issue is that you may not be able to find an index cogset that fits on your existing rear wheel hub. Cogsets have gotten progressively larger over the years as they have gone from 5 speeds to now typically 8-10 gears. This has changed both the sizing of the wheel hubs, as well as the bicycle frames themselves. So to get it all to work you may need to either find older index shifting parts that fit better with your setup, or use a newer cogset that may also require you to use a new wheel axle (or possibly even a new hub- which means a complete new wheel) to accomodate the greater width. If that is the case, you probably will also need to get into bending your frame to accomodate the wider axle spacing. Luckily, your frame is steel and responds well to the small tweaks that will be needed. See here for more info:

So, as you can see, it’s not exactly a straightforward task, and there are lots of issues that can potentially cause a cascading series of other issues. By the time you are done, it may be more money and effort than it’s worth when compared to buying a new or used bike with index shifting. Trek made a number of steel frame bikes back in the 90’s that had index shifting. I picked up one of those for my wife a couple of years ago for $35 from Craigslist (originally was about a $400).

15

You know, in all the pontificating above, I somewhat forgot that you had another bicycle to cannibalize as part of the mix. If you want to try it- move the GT’s rear wheel (including the cogset), rear deraileur, shifter and chain to the Mt Hood and see what happens. Since all these components are matched to work together, you should be ok. Only move the crankset and front deraileur if you run into chain slippage issues.

You may need to pull the rear dropouts apart a bit on the Hood to accomodate the slightly larger new hub- but there is a fair amount of flexibility in the steel frame and you should be able to mount the wheel without permanantly bending the frameset.

16

thanks… just read both posts, and was thinking along similar lines… index-shifting on the rear wheel would be the main addition, so I will take this on as a fall project and see where I get… not sure about the brakes yet…

17

Don’t mess with the brakes- those Suntours are great. Get some new pads and you’ll be good to go.