NewATBikeComute

Bought a Trek 800 Mountain track last fall, now upgrading components (for commute bike).

I wanted to install a larger front gear set, but can't figure out what to do with the front derailleur; label says it's a Shimano Altus, but it's not a style I'm familiar with.

Can I replace this with a clamp on, and how do I remove the old one? Anyone familiar with this type FD?

dedhed

Mech Removal - Front - E-Type | Cycle Systems

NewATBikeComute

Thanks. Looks like I will have to stick to the existing size crankset gears. Lesson learned.

dedhed

It can be replaced with a clamp on that is compatible with the shifters

Kontact 

Why? Most of the replacement cranks you might consider are going to require you remove the BB anyway, why wouldn't you remove the derailleur.

That said, it's an 800. What sort of gearing do you need to make this entry level bike go?

Iride01 

If you try to stay with those square tapers you are going to limit your choices of cranks and chainwheels. Figure out what size chainwheels you want to run, then find what crankset has them and then get the bb that matches the bb shell and the type cranks you are getting.

Yes a clamp on can be had for that bike. Both my bikes have clamp on front DR's. You need to know the external size of your seat tube is to the nearest tenth of a mm so you can get the correct size which might also require an adapter sleeve, bushing, shim or what ever you want to call it.

NewATBikeComute

Iride01 

Cost can quickly get out of hand if you simply replace one thing and fail to notice that something else needs changing. DR's aren't expensive, but when you are talking about a 100 dollar bike, anything you add is lost money. So all you can do is chalk it up to your tuition for an education in bicycle mechanics and balance the cost of fixing up that bike as opposed to getting another bike.

We haven't got all the info to give us a full picture of your situation. Was the previous gearing correct for what you needed? Is the new freewheel the a different gearing and you are trying to make it work by now changing the chainwheels? Are the existing chainwheels okay? Might be cheaper just to get another freewheel that might give the appropriate gear ratios as opposed to the cascade of things you might have to change.

Bike tinker man

Fully agree with above, put it back sell start again, another issue you may have is if you go for a bigger chain set / crank it "might" hit the chain stay, I did that once many years ago then had to install a wider BB then the chain line becomes an issue.

SIMPLE look at everything 1st - not one item at a time

NewATBikeComute

My stubborn streak is not rational, but something I have to overcome sometimes.

Yes, replaced the rear gears, found few options, nearest fit was a bit more compact, starting higher where I have been getting faster over the same commute and really could take advantage of higher, not lower gearing.

So my 'bright idea' was to get a larger front crankset, accepting that I might have to use the smallest front gear from time to time (which I wasn't using at all during my commute). Didn't check for clearance, just pushed the 'buy' button.

One learns from mistakes, and from helpful advice. The mistakes I make on my own, but the forums are great for the latter, even if I find it a bit embarrassing to fess up.

I would like to get this bike into decent shape, ride it the rest of this summer, and pick out something at the next bike swap early next season, and sell this one, knowing that I wasn't passing on a bunch of problems, and that I will be able to feel a sense of pride at being able to evaluate, diagnose, fix, and tune my own ride.