Can I reduce stand over height by changing 29-27.5?

[qwertycube]

My new Trek Rail, size medium, arrived today. However despite matching all published dimensions against my current Cube bike, the Trek is massively too big for me. I’m 5’6 and 30 inside leg.
Is there any reason why I shouldn’t put 27.5 wheels on it and drop it a couple cm. It will still be too big, but it will help?

 

[flash]

Depends.. I converted my Merida eBig9 hardtail from a 29 to 27.5 and it worked out fine. But I also increased the fork travel, changed the stem length, stack height, cranks and bars.

You'll need to make sure your bottom bracket doesn't get too low. It'll suck bashing it on every rock on the trail. And is your 29" fork OK for 27.5 wheels.

You could try shorter cranks if it's the height that's too big or a shorter stem/ saddle position if it's the reach.

Changing the wheels on it's own won't change the bike's sizing. Yes, you'll get a reduced standover height, depending on your tyre choice. The stem, saddle and cranks will change the actual feel of how big the bike is when riding.

I am incredibly happy with how my conversion came out. So it's definitely worth considering.

Gordon

 

[IanVersion2]

I personally wouldn't go in that direction. I'd either keep the bike if I felt able to adapt to the larger size or return and get something that's a better fit.

Am I going crazy or are the frame sizes for those Rails all over the shop? M standover height taller than the L and nearly the same as the XL?

 

[qwertycube]

The next size down is a special order, plus a real pain to return it from where I live. The rest of the frame dimensions are fine, it is just the standover height. On paper it was identical to my Cube Reaction EXC 17”, but in reality the Trek stands 5cm taller. I suspect the Cube and Trek define stand over height differently!
Thus my remaining question, will I produce any unseen negative consequences by switching down to 27.5 wheels?

 

[STATO]

The next size down is a special order, plus a real pain to return it from where I live. The rest of the frame dimensions are fine, it is just the standover height. On paper it was identical to my Cube Reaction EXC 17”, but in reality the Trek stands 5cm taller. I suspect the Cube and Trek define stand over height differently!
Thus my remaining question, will I produce any unseen negative consequences by switching down to 27.5 wheels?

Yes the BB will be lower, how this affects you depends on your riding. Have you checked the bike is in the 'low' geometry position?

Ian is right though, that geo chart is full of errors. Measured BB height that is higher in the low position than the high position? wrong. There are many others that look wrong also.

What is your Cube, can you post a pic of the geo chart?

 

[wepn]

Ian is right though, that geo chart is full of errors

Yes big fail. Trek need to fix that & should swap your bike. My guess is they will.

Otherwise let's see, new wheels & rubber not to mention potential or probable new forks - maybe new bars, stem, cranks, bars etc. Sounds expensive and the bike still won't be what you expected.

 

[STATO]

Ok. realised you had said your bike above and in another thread, so compared the 17" Cube vs M rail in Low, or what should be low, picking the right values. I have an excel sheet to compare bikes, M Rail is longer in the frame but you would expect to use a shorter stem (not shown as i dont know what they come with).

The image centers on the BB, so you can see the Rail (green) is more reach to the bars (50mm) and much higher off the ground (30mm BB + bigger tyres), this is to allow the 160mm travel the Cube does not have. (images are with no sag, as per geo charts)

So, to get more standover you could
1)drop the BB by smaller wheel (risk BB/pedal strike)
2)Smaller tyres would give 10/15mm
3)less travel on the front, 150mm airshaft would give 10mm more clearance
4)size small....

However, the headtube, travel, BB drop, wheel size, are all the same on the S, M or L Rail. The difference of M to S is a 10mm shorter seat tube, and 25mm reduction in reach. So i think the change in standover will be 10mm lower at best, and only near the seat tube, at the front it will be almost the same across all the sizes. (i think when trek say 77.8 for the Medium, they mean 75.8, in between the S and L standover).

Hope that helps?
Maybe not?

 

[qwertycube]

Thanks STATO. It really helps me understand what is differerent. I already understood that the Small size frame appears to be very similar to the Medium. The big difference is in the standover height. The Trek table for standover appears to be using the height approx. 1/3 along the top tube, rather than the more standard? mid-point used by Cude. Thus although most other frame dimensions seemed very similar, or not important, the Trek is much taller.
I've now measured the BB and pedal clearances. The Trek is 4cm higher for both. Thus although I do get the odd pedal/BB strike with the Cube, I'm used to it and its fine. Thus if I switch to 27.5 the bike should only lower by about 2cm. Thus still better than the Cube.
I also need to change the seat as it is much longer and more forward than the cube, forcing me towards a worse standover height.

 

[STATO]

Thanks STATO. It really helps me understand what is differerent. I already understood that the Small size frame appears to be very similar to the Medium. The big difference is in the standover height. The Trek table for standover appears to be using the height approx. 1/3 along the top tube, rather than the more standard? mid-point used by Cude. Thus although most other frame dimensions seemed very similar, or not important, the Trek is much taller.
I've now measured the BB and pedal clearances. The Trek is 4cm higher for both. Thus although I do get the odd pedal/BB strike with the Cube, I'm used to it and its fine. Thus if I switch to 27.5 the bike should only lower by about 2cm. Thus still better than the Cube.
I also need to change the seat as it is much longer and more forward than the cube, forcing me towards a worse standover height.

With BB height, be aware they are un-sagged. The cube being front suspension will only drop the BB ~15mm. The rail being full suspension with 150mm travel will run 50mm sag, and still have 100mm travel remaining. So the dynamic BB height will be the same, but the Rail could go much lower, dropping the BB another 15mm doesnt sound much but in use is quite significant.

Find some other riders your height (in real life or on here) and see what they ride/use. Back in the 90/00s tall riders (like me) had it bad, with short bikes and bad backs. in the 2020s it will be shorter riders at a disadvantage as 'normal' bikes get very long with a lot of travel and 29er wheels. There is only so much you can do when the fork and wheels are so tall, standing room will be lost, but perhaps other riders have found ways to live with or fix that. Id strongly recommend researching that before spending money to change a bike when the consequence could be quite severe.

Good luck.

 

[qwertycube]

Thanks. That changes things. I had not concidered the effect of sag. Fook, I dont even think of myself as that short, but clearly I am!

 

[STATO]

Thanks. That changes things. I had not concidered the effect of sag. Fook, I dont even think of myself as that short, but clearly I am!

Everyone is different, im 6ft4 but cant ride my mates bike, he is 6ft1 but has his seat an inch higher than me!
Check out Katy Winton bike check, she is 5ft2 and rides a 29er Trek.

Bike Check: Katy Winton's Trek Slash - Finale Ligure EWS 2018 - Pinkbike

Winton talks about being small on a big-wheel bike and her setups for the last EWS race of 2018

www.pinkbike.com

You might just have to accept not standing flat footed over the frame, with my shorter legs (relative to my height) some big forked bikes are like that for me, especially on rough ground. Just rest one leg on the top tube.

 

[R120]

You could always try a mullet set up?

 

[tobster]

My new Trek Rail, size medium, arrived today. However despite matching all published dimensions against my current Cube bike, the Trek is massively too big for me. I’m 5’6 and 30 inside leg.
Is there any reason why I shouldn’t put 27.5 wheels on it and drop it a couple cm. It will still be too big, but it will help?

I found the exact thing with my medium Trek powerfly. I'm 5ft 7 and it feels too big. I'm getting used to it but my nuts are taking a battering

 

[qwertycube]

I'm trying to dissociate the fun of going out on the bike ...with a kick in the nuts!

 

[markjl]

Went through the same dilemma as you. Called Trek, and of course they did not recommend changing to 27.5. Did not purchase the bike because of this. I'm 5'8" with 29" inseam and stand over is deal killer (or nut) with the Trek rail bikes. Will probably end up with Levo Comp in medium; doesn't do any good to go to small since same stand over. Not perfect but better than the Rail for comfort. The Levo SL, however is a little taller and feels similar to the Trek.

 

[Gary]

BB height in slack/low setting will reduce from 339mm to 320mm by fitting 27.5 wheels (assuming same diameter tyres on both)

that's 7mm lower than my ESommet. But the ESommet has 10mm more travel front and rear than the TREK. (meaning the Esommet is around 3mm higher at Sag point but 3mm lower bottomed out)
FWIW I'd happily ride a 10mm lower BB on my ESommet.
But... I absolutely LOVE low BBs (coming from a DH background) and don't pedal strike my far lower DH and Enduro bikes (a lot lower than my ESommet)

Most Eebs actually have quite HIGH BBs and none of the modern FS Emtbs I have ever seen or read about have genuinely low BBs
and from what i read on here a very high proportion of Ebike riders are poor at timing pedal strokes and poor at foot position.

Stand over isn't actually all that important when riding. Only when getting on and off the bike. most dynamic riding should be done stood up with the cranks fairly level. this alone gives you 6-7" saddle clearance from a fully extended seatpost height.
your frame standover when stood pedals level is around 16" max

So...

Unless this is you...

...you're doing something VERY wrong if you're hitting your balls on your top tube all the time.

 

[Gary]

one handling trait that will change if fitting 27.5 wheels to a 29" bike is the reduced trail you'll get from the smaller front wheel and longer (than a 27.5) fork offset.
this means your steering will quicken slightly and the bike will be slighty less stable in a straight line.
in reality the 19mm lower BB will actually gain you heaps MORE stability and the only time you'll ever feel the bike being less stable in a straight line is when riding no hands at lower speeds.

Another is that you'll now have slighlty longer chainstays than most 27.5 bikes have. this will create more stability over a standard shorter chainstay 27.5 bike (useful when climbing AND dscending) but slightly less playful and very slightly more effort to lift the front whlle (from a rearwards/downwards body weightshift). Manualling won't be any more difficult but raising the front wheel to manual balancing point will be.

Differences in wheelsize in other situations is swings and roundabouts, ie. 29 should roll over stuff better and deflect less, the downside to this is a 27.5 will change direction quicker and deflection can occur easier.
Neither size is "Better" they're just different.

 

[RickBullotta]

My new Trek Rail, size medium, arrived today. However despite matching all published dimensions against my current Cube bike, the Trek is massively too big for me. I’m 5’6 and 30 inside leg.
Is there any reason why I shouldn’t put 27.5 wheels on it and drop it a couple cm. It will still be too big, but it will help?

If you ride places with rocks and roots, there's a good chance you'll be smacking your pedals on things far more frequently.

I'd try to swap it out with a small. Most dealers would gladly do so.

 

[KeithR]

I'd try to swap it out with a small. Most dealers would gladly do so.

Not that straightforward for the OP - presumably this was a mail order bike rather than one bought from the local bike shop:

The next size down is a special order, plus a real pain to return it from where I live.

 

[KeithR]

Stand over isn't actually all that important when riding. Only when getting on and off the bike.

That's probably the issue, and pretty important in itself - initially, at least.

I'm 5' 7"/30" inside leg, and one of my bikes is a Medium 2016 Cube Hybrid (the Small wasn't in stock and as with the OP, hard-to-come-by special order only) .

My knackers are literally resting on the top tube when I'm standing over the bike, and it took me ages to come to terms with it - I like a lot of fresh air between plums and frame - and it wasn't until I got into the habit of leaning the bike while standing over it that I felt comfortable - and safe - actually riding it.

The standover issue was definitely A Thing™ for me until I was habituated into leaning the bike over.

 

[Gary]

Have you tried tighter pants?

Or do you have the same issue this guy does?

 

[Nicho]

I also need to change the seat as it is much longer and more forward than the cube, forcing me towards a worse standover height.

I had the same problem when I got my Giant Trance last year.

The supplied saddle was extremely uncomfortable, and when I was looking around for a more comfortable one I discovered the ISM PM 2.0 Saddle.

These ergonomic saddles are designed to be 2 inches shorter at the front than a normal saddle, with the result that when I stand over the bike
I am 2 inches further back on the top tube (which has a steep angle) and therefore over a lower part of the tube.

I think that this gave me about 1 inch extra stand-over height.

Obviously all bikes frames are different, but it might be worth trying if you decide you have to keep the bike.

 

[boBE]

I changed the 29" wheels on my Levo SL for 27.5". Apart from the change in trail (that I don't notice) and the lower BB (that I also don't notice since I don't ride rocky trails) it all seems fine and I do like the lower standover.

 

[qwertycube]

Thanks for all replies, particularly that shorter saddle suggestion, that will definately help. In setting the sag the bike has also lowered itself by about 1cm! But my wife is working tomorrow so I'm going to take the 27.5s off her Trek, swap the bits, and try them.
I took the bike out for its first run tonight. 20.4 miles over fairly mixed terrain. I had thought my Cube hard-tail was a reasonable bike, but what a rate the Rail 9 can go. It fair wafted over the rocky stuff. But crushed my nuts at every gate I had to get thru!

 

[Nicho]

But crushed my nuts at every gate I had to get thru!

Have you tried lateral thinking? ......................... becoming a eunuch might solve your problem ...................... but do ask your wife first!

OR

Send your wife ahead to open the gates for you.

 

[GaryT]

I have 2020 Levo M and put 27.5 on rear (Mullet) and this reduced the stand over height by about 12 mm which is just enough so that the bike fits well now.

 

[mtb64]

I would say give it a go. If it works, great, if not, just adapt.
I’m 5.4 with a 27in inseam and ride a 2020 Levo S. I can just tip-toe on both feet when resting on the top tube. Stand-over (or lack of it) is the same with all my bikes except a 2007 14in Orange 5 which I can actually get my heels down whilst resting on the top tube, but again with no clearance. I’ve ridden for 25+ years like this and can honestly say that’s its only a problem when riding technical exposed trails (e.g. Alps) where you might need to stop quickly and get your feet down. Had some scary moments on trials like these and now generally avoid them. So, for 99% of my riding, I’ve just adapted to it.

 

[qwertycube]

Update. Swapping to the 27.5 wheels worked absolutely fine, particularly when I decreased the sag to 25%. Standover dropped about the 2cm. The bike felt a lot smaller. Rode it around familiar trails, no clearance issues although not much to spare. However, after pushing the seat back, running 35% sag and getting used to using a dropper post for first time, the bike will be fine on 29s. Thanks for your replies on this subject.

 

[jazzhands01]

I changed the 29" wheels on my Levo SL for 27.5". Apart from the change in trail (that I don't notice) and the lower BB (that I also don't notice since I don't ride rocky trails) it all seems fine and I do like the lower standover.

I did the same. I also replaced the cranks with the hope 155 ebike cranks and it rocks. just about the same clearance as stock. I f*ckin love it!