Folding Bikes - Modifying a Capreo

I'm thinking of eventually getting a Capreo hub and cassette. At present the tikit has an 11-26 rear cassette with a 53T front ring, giving me about 30.4 -- 77.4 gear inches according to Sheldon. I'm strong enough that I could use some more top-end. A Capreo (9-26) would give me 32.8 - 94.6, a lot better up top. But I'd love to keep that 30.4. A 49T front ring would shift back down to 30.3-87.5, but that's a loss.

So I'm wondering what cog options I might have in tweaking a Capreo to be 9-28, 9-30, or 9-32. 9-34 seems unlikely. The Capreo's cogs are 9-10-11-13-15-17-20-23-26.

Are any of the following realistic and/or easy to obtain?

9-10-11-13-15-18-21-24-28

9-10-11-13-15-18-22-26-30

9-10-11-13-15-18-22-26-32

etc. Suggestions?

The 1st option differs mainly in the biggest sprocket; that gives less than 10% difference to the original, so I would discount that one.

The 2nd one would be hard to obtain - I am not aware of any 9sp cassettes with a 30T largest cog.

That leaves the 3rd one. But that one is also of different jumps than a standard cassette, so in each case you are forced to buy several cassettes to make a single one - very expensive.

I think either

* a front ring (smaller than your suggestion to make it really worth the effort),

or

*just the biggest cog in the capreo replaced with a 32T one for a bailout gear.

But I have no idea where to buy just a loose cog; it may be beneficial to contact a bike shop for old MTB cassettes, since the large cogs are seldom worn much at all.

You can get modified 9-34 capreo cassettes here for £75.58 plus shipping:
http://www.ice.hpv.co.uk/

There's also the issue of derailleur size. It's a tikit, after all. I was attracted to 28 because the existing tikit has a 28 and wouldn't need anything special; but I'm not sure if the existing derailleur can handle 32 or 34. And definitely not sure if the special capreo short-distance derailleur could handle them.

I'm pretty sure that Bike Friday was offering a custom capreo for one of their bikes at one point. Why not ask them what the relevant issues are?

One possiblity is to go for dual drive instead, this would get rid of the drailer reach issue, and give upgearing of around 36% rather than the cespros 20% ish on a 53 front. But the dual drive can generate potential interferring with the fold due to the toggle chain or click box. The cespro is therefore a neater solution to up gear.

I'm thinking of eventually getting a Capreo hub and cassette. At present the tikit has an 11-26 rear cassette with a 53T front ring, giving me about 30.4 -- 77.4 gear inches according to Sheldon. I'm strong enough that I could use some more top-end. A Capreo (9-26) would give me 32.8 - 94.6, a lot better up top. But I'd love to keep that 30.4. A 49T front ring would shift back down to 30.3-87.5, but that's a loss.

So I'm wondering what cog options I might have in tweaking a Capreo to be 9-28, 9-30, or 9-32. 9-34 seems unlikely. The Capreo's cogs are 9-10-11-13-15-17-20-23-26.

Are any of the following realistic and/or easy to obtain?

9-10-11-13-15-18-21-24-28

9-10-11-13-15-18-22-26-30

9-10-11-13-15-18-22-26-32

etc. Suggestions?

I suppose that you have a typo there and your present cassette is a 11-28.

Other than the four smallest cogs which fit the special shape of the freehub, the Capreo cogs are nine speed shimano cogs and you can replace them with such.

http://www.sheldonbrown.com/capreo/index.html
http://www.sheldonbrown.com/k7.html#custom

The Harris Cyclery will make custom cassettes for you including custom Capreo cassettes provided you don't change the four smallest cogs.

I have never seen a capreo derailer. My guess is that it has a short tension pulley but I don't know how much extra capacity it has beyond the single chainring it is designed for. But whether a derailer can work with a big cog is determined by the placement of the jockey pulley which is adjusted by the b-screw.

I know that a short cage shimano rear derailer will almost always fit a 30-tooth cog and my personal experience is that I have never failed to fit a cassette with a 32-tooth cog mated with a road derailer. Apparently, there are frames with very short derailer hangers where this might be an issue such that you have to use a MTB rear derailer ... but as I wrote above, I have never personally experienced it.

Note that there is no reason why you have to use the Capreo rear derailer with the Capreo cassette. Only the cassette and rear hub are needed. You will need a nine speed shifter.

The Capreo derraileur can handle 32, I would think, as the cage is fairly long.

At a folding bike race a few years back a fellow had a 9-32 on his Birdy with an Alivio long cage that he really liked. The bike had a lot of miles on it.

Makeinu's point about turning to the recumbent world for fancy parts is a good one. I had no idea there were so many high end small wheel bits until I started looking at the possibility of buying a recumbent. Take M5, for instance: http://www.m5-ligfietsen.nl/site/EN/News/Latest_news/

One question I'm really wondering is: what's the biggest jump in percentage of teeth that is reasonable? If I just slap a 28, or something bigger, onto a Capreo as the last cog, that'd create a jump from 23-28 or higher. Is that reasonable to expect from a derailleur?

feijai, why not? Shimano already do a 24-34t jump on some of their cassettes.

I think only 3 cogs are Capreo specific. My 10 speed BF Capreo hub on my BF PR has 18-17-16-15-14-13-12-11-10-9 cogs. The 18 thru the 12 are D/A 10 cogs. My rings are 50-34.

My Speeding Tikit will have the same cogs with 53-39 rings.

I wouldn't expect a huge jump to go with the same smoothness as a small one but it would go. I jump from a 38T to a 60T on my Moulton (front, but rear should be as feasible).

I think only 3 cogs are Capreo specific. My 10 speed BF Capreo hub on my BF PR has 18-17-16-15-14-13-12-11-10-9 cogs. The 18 thru the 12 are D/A 10 cogs. My rings are 50-34.


http://www.sheldonbrown.com/capreo/index.html
http://www.sheldonbrown.com/k7.html#custom

Four ... assuming Sheldon knows what he is talking about.

Whatever Bike Friday did is engineered on their part since they also changed the spacing.

not intending to hijack this thread:
I would like to ask this question..: when was this capreo hub and cassette introduced?
how come the price is still high? (relatively)

I was thinking of buying the set, and removing the second largest cog, so it would become a 8 speed
and putting this set on a 16" folder

quote "how come the price is still high? (relatively)"

shimano dont seem to market the cespro range widely at all. Therefore it remains a special order from most bike shops, and is virtually never offered at a sale or a discounted price. I don't understand how they expect to sell many if they do not make people aware of it. Is their heart really behind this product range?

not intending to hijack this thread:
I would like to ask this question..: when was this capreo hub and cassette introduced?
how come the price is still high? (relatively)

I was thinking of buying the set, and removing the second largest cog, so it would become a 8 speed
and putting this set on a 16" folder

FYI, the cog spacing is wrong for 8-speed indexing systems.

Given its differences from the regular production 9-speed systems and smaller numbers, it doesn't surprise me at all that prices are higher. Moreover, what good derailer based alternatives are there to Capreo? Moulton offers a 9-tooth cog cassette -- at least they did a few years ago -- that I am told is much more expensive. So the Capreo system is a relative bargain! ;)

According to Rob English, BF did not have to modify the 12 tooth cog from the Ultegra 10 cogset I sent him for my Tikit. So only the 11-10-9 tooth cogs are from the Capreo on my 10 speed Tikit.

Was that set up a lot cheaper than the cespro cassette?

According to Rob English, BF did not have to modify the 12 tooth cog from the Ultegra 10 cogset I sent him for my Tikit. So only the 11-10-9 tooth cogs are from the Capreo on my 10 speed Tikit.

Well, he would know!

correct me if I am wrong, but isn't the four cogs, 9-10-11-13t, inseparable?
I mean they are detachable, but they must be together?
so, how come folderfan has a 12t?

by the way, finally got myself a freehub and cassette.
for approx. 100 dollars...
will try to copy the 9-10-11-13t, probably as a cluster....
but first must find a shop with CNC machine....

correct me if I am wrong, but isn't the four cogs, 9-10-11-13t, inseparable?
I mean they are detachable, but they must be together?
so, how come folderfan has a 12t?


The capreo 13t is just a normal 13t cog of 12-13-... 9sp cassette. If you could find a 12t cog from a 9sp 11-12-... cassette, it can be used with capreo 9-10-11 cogs.

Understand that the tiny 9-10-11 tooth cogs of the Capreo are very inefficient.

In other news, a Sturmey-Archer XRDK8(W) IGH geared 53/25 would yield 34-110 gear inches on a tikit.

HTH,
tcs

Understand that the tiny 9-10-11 tooth cogs of the Capreo are very inefficient.


Very is a 'relative' sort of word. Sure, cogs smaller than 15 t show more losses but the days of racers using >56 t chainrings are long gone. They don't find too many problems with using 11 t and 12 t cogs. There is a bit of 'roughness' evident through the pedals with 9 t cogs (chordal action) but that doesn't actually absorb 'too much' energy. It is fairly rare for riders to spend lots of time in a 9 t cog, the gears are generally a bit too high for normal riding, even with small wheels. Not too many can turn over >90 gear inches as a general ride-around gear.

Those small cogs do wear faster in any case, so not using them too much increases time before replacement.

Very is a 'relative' sort of word. Sure, cogs smaller than 15 t show more losses but the days of racers using >56 t chainrings are long gone. They don't find too many problems with using 11 t and 12 t cogs.

Here's some non-relative, empirical data (begins on page three):

http://www.ihpva.org/HParchive/PDF/hp52-2001.pdf

The study only covers down to a 12T, and you mention an 11T - but the OP is talking about using a 9T with even greater pin loading and angular link deflection.

If you know about bike racers, you'll remember Lance Armstrong's famous highest-in-the-peleton cadence. He would often turn a 53/13 where his competitors were turning a 53/11. Both theory and test data says that because of his larger cog Armstong was operating a drivetrain that was more efficient...and he won the Tour de France and his competitors didn't.

tcs

Here's some non-relative, empirical data (begins on page three):

http://www.ihpva.org/HParchive/PDF/hp52-2001.pdf

The study only covers down to a 12T, and you mention an 11T - but the OP is talking about using a 9T with even greater pin loading and angular link deflection.

If you know about bike racers, you'll remember Lance Armstrong's famous highest-in-the-peleton cadence. He would often turn a 53/13 where his competitors were turning a 53/11. Both theory and test data says that because of his larger cog Armstong was operating a drivetrain that was more efficient...and he won the Tour de France and his competitors didn't.

tcs

First, that Lance Armstrong won the Tour is at best evidence but definitely pretty far from a proof.

Second, I seem to recall some people thinking that the smaller wheels offset the effect you discuss (http://www.bikefriday.com/gearing). Years after the discussion, on the YAK group, John decided that his argument was wrong.

correct me if I am wrong, but isn't the four cogs, 9-10-11-13t, inseparable?
I mean they are detachable, but they must be together?
so, how come folderfan has a 12t?

by the way, finally got myself a freehub and cassette.
for approx. 100 dollars...
will try to copy the 9-10-11-13t, probably as a cluster....
but first must find a shop with CNC machine....

The 9t-10t-11t are seperated cogs that fit together and the 11 fits on the 10 speed 12t just fine.

Both theory and test data says that because of his larger cog Armstong was operating a drivetrain that was more efficient...and he won the Tour de France and his competitors didn't.



I suspect that drugs have much more effect than any difference in gearing.

I'm familiar with the paper and acknowledge the efficiency difference. As mentioned, no racer nowadays uses 56(+) tooth chainrings to ensure that they time trial in larger cogs. Using 11 t and 12 t cogs for time trials is commonplace, suggesting that the efficiency loss of smaller cogs is 'not too significant' overall, particularly for non-racers.