sisimonmon

Hello everyone ! This is my 1st post on this forum sorry if i'm in the wrong section and/or my problem is on another thread !
Here's the deal : I recently bought a vintage cannondale SR600 from around 1986. The bike is stunning I'm completly in love with it but there is one problem that I can't find with it.
This is not my first vintage bike, I also own a 1991 CADEX, and when I compare both its night and day, I would say the cannondale feels 35% slower (effort to power output). I went on a group ride for around 2h30 with the CADEX and was in front the whole time the next ride with the same group I was heavily behind after 20min of ride lol. So it is safe to assume something makes the cannondale slower. I gave it a deep clean aligned the shifter trued the wheels and all and still the same results. Maybe the tires are bad ? or they can inflate enough so it makes it slow ? I really don't know and that's what brings me to the forum to seek for some wisdom ! (Note that this is a 6 speed cassette with friction shifters maybe that makes a difference ? idk )
f you have any idea what makes it slower please enlight me !

bargainguy

Welcome. It's impossible to tell at a distance what the issue is, but we can speculate.

First thing I'd do is put the C-dale on a work stand and verify wheels are spinning freely with no resistance, tires not rubbing on the chainstays, properly centered in dropouts, etc.

If they're OK, then on to check wheel hub and bottom bracket bearing condition. On a 1986, chances are you need a rebuild asap, as any grease from that long ago is no longer functional.

Also, hubs that are overtight will cause binding and require more effort to pedal. It could be something as simple as that.

Friction shifting + freewheel (probably not a cassette from 1986) shouldn't make a difference as far as effort. Properly tuned systems should be equally easy to turn.

sisimonmon

Wow thank you for the fast response ! I did think about the bearings and will try to find a way to check them ( I don't currently have the tools, if you have a magic solution to check bike bearings condition without tools I'll gladly take it lol). But when I compare the 2 bikes ( the CADEX and the Cannondale) the wheels seems to spin relativly the same on their own, which really makes me think that the tires (Cheng Shin tyres) are bad and need replacing. Is it causing the bike to feel around 35% slower maybe not..

jdawginsc 

Tires can seem to make a difference as well. Are they both the same make? Different widths? Different tread patterns? Body positioning?

In fairness to the design, that was Cannondales first attempt in racing/touring builds and geometries. The tubings were much different size wise, first to CAAD. Steel fork on the early ones as well.

I love my ‘87 Crestdale, but it is definitely slower than my steel Basso from the same year. The 90ish Rossin made from ELOS is a rocket ship comparatively.

dddd

I recently (January 1) bought and started riding a 1970's Bridgestone Submariner road bike which while quite heavy, was nevertheless far more sluggish feeling than just the weight could explain.

I found that the derailer pullies had a lot of viscous resistance to turning, which stole a lot of power since they rotate at higher speed than other parts on a bike and because there are of course two of them. Some heavy oiling applied while the bike lay on it's side fixed that right up.

Another thing to check is for the presence of "armored" style of tires, or thick, "thorn-resistant" inner tubes (or tubes containing old sealant).
A Trek hybrid bike I once purchased had original "Hard Case" tires that imparted an incredibly slow feel to the bike's rolling ease (but which actually could stop goat-head thorns from penetrating).

One last thing to compare between your two bikes would be the chainstay length. Also the sponginess of any suspension fork.

And an old-fashioned "bushed" chain will impart far more friction than newer bushingless chains when the chain is angling sharply between offset front and rear sprockets (i.e. while cross-chaining).

Pulling the chain away from the sprockets will allow one to independently inspect the rear hub and crank axle for ease of turning.

nlerner

Can you swap the wheels of the two bikes and test ride? That'll tell you a lot about the contribution of wheels/tires/bearings.

dddd

Are the brakes perhaps rubbing? This doesn't always produce tell-tale noise. It's usually caused by either a warped rim or by one side of the brake having more spring tension than the other side, often because of a "stretched" spring (or broken plastic spring tension adjuster, which is a common issue on certain years of Shimano's lower-tier cantilever brakes).

Classtime 

Are they stock bikes? Friction shifting the Cannondale vs. Index on the Giant MIGHT have you in the less optimal gear riding the Cannondale in a fast group. You need to put nice tires on both bikes to compare. Are saddle, pedals, and bars in the same place relative to each other and the dropouts? My 86 Cannondale is as fast as (or faster than) any of my other bikes.

sisimonmon

One of them is 6 speeds and the other is 7 so not sure that I can swap the rear wheel. For the really resistent tire part, it is indeed a totally different feel from my cadex wheels, they feel like heavy duty lol.
I there is no rub on anything when riding / spinning the wheel ( would of love that its an easy brake tension problem lol). I will buy some new tires and inner tubes, I'm reading online that latex innertubes are faster. Thank you all for the responses this is very insightful I will find the mysterious problem with your wisdom

sisimonmon

The shifter for the rear derailleur is somehow indexed ?? It's another plastic part that came with the bike and it does feel amazing to have a indexed friction shifter. Everything is in the same place (mesured from the center of the crank). I think that from alot of the answers I've received it is indeed the tires that are crappy chinese nuclear resistant rubber lol.

KCT1986

There shouldn't be anything inherently slower on the design on the Cdale. It may be a little heavier @ 21 pound but common for mid 80s. Wheels are probably 36 spokes, also common. The rest of the components are probably common for the timeframe, nothing 'cheap' was used by Cdale, standard Suntour groups on mid level bikes. A proper inspection & service of all parts could reveal some issues but probably not significant.

One of the benefit was the cost/stiffness/weight ratio of the Cdale.

Probably a tire change, already mentioned, would give you a better comparison. Because of the stiffness of the frame, you'll need to assess if that may be causing you to be less efficient or effecting your fatigue level.

dddd

Oh, and sometimes a flat-resisting tire liner can cause a lot of rolling resistance, depending on the brand (Mr. Tuffy ones have the very lowest rolling resistance, who knew?).

I bought one bike where there was some kind of garden hose looking material inside of the tires, which ran airless.

I've got an '89 Cannondale MTB that's got cheap Taiwan full knobby tires yet still feels pretty lively. I felt some thumping at high speeds after I first found it (free), which turned out to be thickened sealant in the tubes. Much better now after I replaced the original chain and re-hydrated the old tire sealant with water, also lubed up the entire bike, re-spaced the rear axle and re-dished the rear wheel, etc.

Chombi1 

Uhmmm......Maybe more aero drag from the fat frame tubes??

gearbasher

How about your position on the bike? Are both bikes set up identically?

hayden52

This. Your position can make a huge difference in the amount of power you can put out. Check to see how different the positions are between the two bikes.